In manufacture, the mica separators are coated with a solution of Magnesium Oxide to iimit potential leakage path length  and provide a repellant mono layer to prevent surface deposition, however, the user can take measures to prevent deposition by always running their valves within recommended maxmal limits such that they do not get overrun and overheated - remember those manky EL84!   Rectifier and output valves by nature of use have high anode current loadings and consequently can run very hot, however, manufacturers had designed in a number of mechanisms to combat excess heat - did you admire those sexy black anode coatings in your rectifiers ... boutique or not, alas NOT because although it looks pretty, it exists to dissipate heat more effectively - what about that PX4 with a fin mounted orthogonally against the anode ... not just there to look nice and provide a certain sound but yes, you've guessed it, it's there to help dissipate heat more effectively

Valve manufacturers include a component within the valve that 'mops up' residual gas - this is the getter flashing - that pretty silver mirror like coating seen on the inside of a valve's glass envelope.  The flashing is a deposited barium metal mirror, which originates from the getter rings and pans that form part of a valve's structure.  After evacuation the sealed valve is subject to an inductive RF heating pulse which evaporates the metallic barium from the getter ring/pan onto the envelope.

This mirror is sacrificially consumed as it 'mops up' gas within the envelope and many of us will have seen an elderly valve where the getter flashing takes on a brown and then a pinky-white hue as it's absorbtive properties have exhausted - all schoolboys of a certain age will also be familiar with the silver getter flashing disappearing to a dull white powdery coating as the valve envelope is broken either by stones, airgun pellets, Dinky toy collisions  or other means thus letting atmospheric oxygen in to consume the getter flashing!

OK, so we have got a bit of gas left in a valve and something to sort out any that's left, what does the gas actually DO, can it be a problem???? 

The answer is a resounding YES for as the gas molecules 'bimble' and 'gambol' in Brownian motion within the envelope, electrons from the cathode 'belt' into the gas molecules causing them to shed their own electrons and become positively charged cations.  These positively charged gas molecules are then attracted to the negatively charged grid where they tend to nullify the grid bias making the anode current increase.  Unfortunately this can start a cascade effect as mure current causes more gas molecules to ionise and the anode current can continue to rise such that a sort of meltdown occurs in which the valve destroys itself. 

In reality though. often long before this happens, the positively charged gas molecules are simultaneously attracted to the cathode where they bombard the emissive coating, forming a non emissive layer on the cathode surface called  'poisoning' which reduces emission to very low evels and renders the valve useless.  Could that be what has happened to that bargain valve with 5% emission - is it a victim of gas attack?

During the early life of a valve, the effect of emission loss is realtively imperceptible but after a while, the multual conductance, gm, falls off significantly.  The following graph shows the change in gm with negative grid current at three points in a particular valve's life; curve A is the valve when brand new; curve B after burn in and curve C when worn and showing less than 50% emission.

You can see also that the slope of the curve changes too and the sensitivity of the valve is measured by the steepness of this slope.  The effect of shallowing of the slope means loss of volume, loss of sparkle and increase in distortion due to overloading.   So you can see now why an emissive limit of approx 50% may be considered the bare minimum for continued usage and typically an emissive limit of 70% for a valve to be considered to show reasonably good emission.

In our next blog entry we will look at some other things that happen as valves 'wear out'.

These capacitors, introduced to the radio market in 1964 have a polyester dielectric which exhibits very low dielectric loss, high insulation resistance coupled with good temperature and moisture resistance, however, for physical integrity they are not perhaps as tough as the Mullard ‘Mustard’ capacitors.   All told though, they far exceed the efficiency of paper dielectric capacitors and impart a very similar sonic signature in audio applications, indeed many classic guitar amp designs utilize them in construction I am told.

Although they are colloquially referred to as ‘Tropical Fish’ capacitors, their true moniker is the C280 Miniature Metallised Polyester Film Capacitor and they came in two voltage ratings, 250V and 400V wkg.  I have been asked how to read the colour codes and here is a handy diagram to help with that task:-

In literature and original Mullard packaging, the C280 series is described by codes and I am often asked how to interpret these, well, the prefix C stands for capacitor, 280 is the series type of the capacitor, the prefix commences with AE for  250V rating and CF for 400V rating.    The coding will then continue in the form C280yy/xxx. where the first (post slash) letter that indicates the tolerance of the capacitor.  In the case of the 280 series, A = +/- 10% and P = +/- 20%. The continuation of the code is based on the capacitance value of the device where a numerical figure is followed by the letter K or M.  In summary, one can always easily read the capacity of the device by considering the letter K to equate to the unit nF and  the letter M to equate to the unit uF with the numerical component to be the value. To translate the nF or uF  value into other units of capacitance, the following conversion factor may be applied.

1uF = 1000nF = 1000000pF

Anyhow, because I am a top geeza, I have produced a table showing the ENTIRE range of C280 capacitors ever made with their corresponding codes and capacitance values in various Farad units - pretty good huh?

TYPE NUMBER	CAPACITANCE (uF)	CAPACITANCE (nF)	CAPACITANCE (pF)	WKG VOLTAGE   (V)
C280AE/A330K	0.33	330	330000	250
C280AE/A470K	0.47	470	470000	250
C280AE/A680K	0.68	680	680000	250
C280AE/A1M	1.0	1000	1000000	250
C280AE/A1M5	1.5	1500	1500000	250
C280AE/A2M2	2.2	2200	2200000	250
C280AE/P10K	0.01	10	10000	250
C280AE/P15K	0.015	15	15000	250
C280AE/P22K	0.022	22	22000	250
C280AE/P33K	0.033	33	33000	250
C280AE/P47K	0.047	47	47000	250
C280AE/P68K	0.068	68	68000	250
C280AE/P100K	0.1	100	100000	250
C280CF/A330K	0.33	330	330000	400
C280CF/A470K	0.47	470	470000	400
C280CF/A680K	0.68	680	680000	400
C280CF/A1M	1.0	1000	1000000	400
C280CF/P10K	0.01	10	10000	400
C280CF/P15K	0.015	15	15000	400
C280CF/P22K	0.022	22	22000	400
C280CF/P33K	0.033	33	33000	400
C280CF/P47K	0.047	47	47000	400
C280CF/P68K	0.068	68	68000	400
C280CF/P100K	0.1	100	100000	400
C280CF/P150K	0.15	150	150000	400
C280CF/P220K	0.22	220	220000	400

But let's put sexist stereotypes aside for a moment and look instead at the reality of valve testing at Mullard in the 1950s - did you know that at the Mullard Service Department at Waddon, the majority of staff were 'wimmin' yes, really, and to prove it here, below,  I have photos of Doris Saxilby and Mildred Dallymer each carrying out valve testing in the  Waddon labs.  Did you also know that at all times, when returned valves were actually on test, manualy dextrous operators such as these two pictured would be lightly tapping the valve with a leather covered hammer to reveal any intermittant faults - how stimulating. 

This wouldn't do at all so Mullard helpfully introduced three tools to aid service engineers and dealer personnel alike - these still resurface today and I have lost count of the number of times a bemused and inquisitive finder has asked me what these strange implements are.  And here we have a picture of the tool trio - any guesses what they are and what usage these might be put to? - 

Own up, who got it right... working clockwise, first we have the soldering jig which allows soldering to the valve bases to be carried out without causing distortion, next, a valve pin straightener and finally a rubber grip which when fitted over a valve envelope, would allow removal of the valve from it's base - handy when warm and buried deep in a chassis.

Mullard advertised the change as ergonomics with  an added security measure, to stop customers from interfering with the valve tester, the knob and arm could be unscrewed to prevent meddlesome usage by  shifty spiv types and young schoolboys with caps, short trousers and sticky fingers.

You know, it is said that there is nothing new in show business or advertising and here we have three photos just to prove this point.

Here we see Petula Clark in October 1950 at the Castle Bromwich Radio Show somewhat agog at the size of this 5 foot Mullard valve model.

And this 'ad opportunity' was again exploited  with a young lady from  Chorley Wood College for Girls with Little or No Sight examining the same giant valve model at the London Science Museum in November 1950.

But this wasn't a novel approach at all, because in 1927, Telefunken's Frau Traudl Schmink did it first - and her valve was 2 metres in height, what a whopper!

This valve testing apparatus is capable of carrying out tests as similar as possible to those standard production tests to which all Mullard valves are subject. The tests are not of course as exhaustive as those carried out during manufacture but they do ensure that the valve under test is satisfactory in all respects insofar as it is within the approved tolerances of operation.

Use of Punched Cards:  arrangement of the test circuit and selection of test parameters is performed using a  perforated card corrresponding to the valve under test.

This card is inserted into a gate switch contained within the valve tester.

Three such cards are supplied with each instrument for use when setting up and adjusting the tests.  Numbered and punched cards for the actual tests are available together with a printed list giving the valve types and the reference numbers of the corresponding cards.

Three Test Limits:  in place of a moving coil meter, a cathode ray tube (CRT)  and vertical coloured scale are employed to indicate the results of various tests.  If the valve is within specified limits, the spot on the screen of the CRT is defelected to the green part of the scale.  If, on the other hand, the valve fails to meet the test requirement, the spot is deflected to the red part of the scale.  a reading in the intermediate part of the scale indicates that the test valve will soon need replacement.

But the real pity was that the  CRT based 'snog-marry-avoidometer'   style of indication allowed no quantitative estimation of valve performance to be made - the MH-SVT  was useless for valve matching.

In actuality, the spot was sometimes quite hard to see - just like in this photo - so, let's switch to an infra red view, you can make the spot out  in the lower portion of the green section as a dirty smudge, hey, this reminds me of spotting Halley's Comet in 1986 - is that it.....

Construction:  the test apparatus is mounted in a metal case with a sloping front.  All internal components are readily accessible for servicing by removing one or more sections of the case.

The top panel carries a complete range of valve holders and a flying lead for top-cap connections.   On the top is also a slot into which must be inserted the perforated card corresponding to the valve under test.  The gate switch is operated by depressing the right hand carrying handle.  This switch carries 130 pairs of contacts which  are selected by the punched card.

In the later 50s Mullard described the hammertone finish of the MH-SVT as being a 'densito finish' - can' think why though.   The gate switch contacts were an inspired idea, however, their complexity made them liable to corrosion, arcing and consequent unreliability.

At the top right hand side of the front panel is situated the switch which selects the tests in sequence and below it is a rotary switch by means of which fine adjustment of the operating voltage can be made in accordance with the prevailing voltage of the supply mains.

To the left of the CRT are four buttons by means of which individual electrodes may be tested for short circuits, insulation and open circuits.

The front panel carries a removeable plate behind which are situated the adjustments for zero setting, reject limit setting, brilliance and focus and for lateral shifts of the spot in case phosphor burn becomes a problem, a fresh part of the screen may be used.

It is said that some dubious dealerships encouraged customer valve testing, often at the cost of 6d to 1/- on a MH-SVT whose reject limit settings has been adjusted very high so that a good valve would appear marginal.   A West Yorkshire ex TV Engineer pal told me that his boss bragged that  he achieved a 50% on test replacement valve sale rate by using this deplorable tactic. 

Mains Adjustment:   the instrument has been designed to perate on 50 c/s AC from 180 to 260 volts. Adjustment of the various voltages is by means of 20V tappings on the mains transformer located on the control panel in conjunction with an eleven position rotary switch operating in 2V steps situated on the indicator panel and marked MAINS ADJUST.

Initial & Periodical Check Routine:  to ensure correct function, special check cards must be used to check mains voltage against an internal standard.  Meter sensitivity and HT stabiliser may also be checked.

The design brief and the problems in meeting this requirement specification was interesting,  the new tester had to be 'modern',  compact, accurate, give a fast stable result - automatically, be easy to use by non-skilled personnel and finally, most important, be fitted with safeguards to prevent damage to tester and valve under test in the event of incorrect operation.  All this added up to a tall order indeed.

The 'modernity' aspect was provided by housing the new tester in a hammertone silver finished case having a low aspect, 'crouching' on the bench.  Difficulties with sourcing suitable moving coil meters for test indication allayed to the 'no damage on misuse' design brief lead to the novel concept of using a cathode ray tube for test indication - a twin edged sword - for although there was no meter to burn out, there was no way to get a discrete quantitative estimation of measured test parameters, however, it was felt that service departments only required a go/no-go indication anyway.  

It is quite amusing now looking back that much was made of the new tester's bench footprint of 16 inches square and a height of only 12 inches.  Not a bad result, however, this new tester drew much from the Mullard Master Test Board of 1935 in that similarly, it depended upon the use of punched paxolin cards to be inserted into a gate switch to set the test parameters for a specific valve under test - with over 8000 valve types in service and a requirement for at least 250 cards to cover the most common, storage for the associated cards was both bulky and commensurately heavy!!

We will look at the Mullard High Speed Tester in more detail in a future blog but I should like to finish by explaining  - in Mullard's own words - a little about what this device could do:-

"A non technical person could learn to use the new tester safely and effectively after 10 minutes of instruction.   After inserting the correct card for the device under test and utilising a simple arrangement of switch and push buttons can, under working conditions test for faults with: inter electrode insulation, continuity of electrodes, degree of emission, grid current, and heater cathode insulation with the position of a moving spot on the cathode ray tube indicating whether or not the valve on test is or is not within it's proper operating limits."

Interesting though, that many preferred this little number by a competitor, similarly priced but slightly lower such that the savings would allow a pretty nice austerity lunch for two, pass the salt old bean, my Brown Windsor soup is a little insipid.  Sir Stafford Cripps would certainly approve.

RADIO	VALVE LINE UP
EKCO A21	ECH35 EF39, EBL31 AZ31 EM34
EKCO A23	ECH35 EF39, EBL31 AZ31 EM34
EKCO A28	ECH35 EF39, EBL31 AZ31 EM34
EKCO AC64	AC/S2PEN VP4 2D4A PENA4 IW2
EKCO AC74	SP4 VP4 TDD4 PEN4VA IW3
EKCO AC76	FC4 AC/VP1 2D4A PEN4VA IW3
EKCO AC77	FC4 VP4B 2D4A PENA4 IW3
EKCO AC85	AC/S2PEN VP4 2D4A 354V IW3
EKCO AC86	AC/S2PEN VP4 2D4A 354V IW3
EKCO AC97	FC4 VP4B TDD4 AC042 TV4 IW4/350
EKCO ACT96	AC/VP1 FC4 AC/VP1 2D4A 354V PEN4VA IW3
EKCO AD36	SP13 HL13 PEN36C 1D5
EKCO AD37	VP13C SP13C PEN36C UR1C
EKCO AD38	VP13C SP13C PEN36C UR1C
EKCO AD65	VP13C SP13C PEN36C UR1C
EKCO AD76	VP13C SP13C PEN36C UR1C
EKCO AD77	VP13C SP13C PEN36C UR1C
EKCO M23	S4VA 354V PM24M
EKCO U109	UF41 UCH42 UBC41 UL41 UY41
EKCO U29	CCH35 EF39 CBL31 CY31
EKCO U49	CCH35 EF39 EBC33 CL33 CY31
EKCO U75	CCH35 EF39 EBC33 CL33 CY31
EKCO U76	UCH42 UAF42 UAF42 UL41 UT41

An elderly couple are listening to a preacher on their Atwater Kent breadboard radio when the preacher tells the listeners "If you need healing today, I want you to place a hand on the part of your body you need healed, then place your other hand on the radio's output valve and you will be healed!"    The old man slowly places a hand on the power output valve then  inches his other hand  firmly down the front of his trousers.     The old lady, looked up from her knitting, narrowed her eyes, pondered for a moment and then sharply said  "Don't be so silly,  he said he could heal, not perform a miracle in raising the dead!"

Tee-heee, a good un I think!!!!!!!

Year of Introduction	Valve Base Type	Descriptive notes
1916	B4	Introduced by French valve manufacturer Duclos-Fivre
1927	B4 + side screw	Introduced for indirectly heated cathodes
1928	B4 + top cap	VHF/ UHF anode top cap connection
1928	B5	An extra pin for the pentode
1933	B7	More extra pins for the heptode
1934	B9	More extra pins for the nanode and dual triode
1934	Ct8	Philips side contact to stop competiton sales
1935	5AA	Acorn valve by RCA in the USA
1935	IO	International Octal introduced in the USA
1935	7AA	More acorn valves by RCA in the USA
1937	B3G	Introduction of TV boost diodes
1938	MO	Mazda’s independant Octal base is introduced
1938	B8G	Loktal introduced in the USA for military use
1938	B9G	By Philips for the EE50 and EF50
1939	B7G	Introduced in the USA by Sylvania & RCA
1947	B7G	Brimar & Mullard use for the first time in the UK
1948	B8G	Mullard use for the first time in the UK
1948	B8A	Brimar & Mullard  first UK use of ‘Rimlock’
1948	B9A	Introduced in the USA by Sylvania & RCA
1951	B9A	Mullard use for the first time in the UK

The Russian military Standard Operating Procedure for thermionic device numerication is documented in the 1959 issued GOST 5461-59.    The numbering system comprises of a four character system.  Thermionic devices MUST have a complete four character code,  however, where a  character is   not required  as a device descriptor then a dash should be included in it’s place.          On no account must the code ever be shortened from the prescribed four character code (or you will be sent to Siberia).

The second (2o)  character defines the electrode structure for a device
Д	Diodes
X	Double diode
C	Triode
з	Tetrode
Л	Power pentode & beam tetrode
K	Remote cut-off pentode
ж	Sharp cut-off pentode
B	Secondary emission pentode
A	Twin grid mixer & hexode valve
ъ	Pentode with one or two diode
г	Triode with one or more diode
E	Tuning indicator
й	Triodes with hexode, heptode or octode
H	Double triode
P	Double tetrode or pentode
ф	Triode - pentode
л	Rectifier
Type sequence number	Gas-discharge rectifier
г	Gas thyratron
P	Mercury thyratron
X	Cold cathode thyratron
пM	Oscilloscope tubes with electrostatic deflection
пM	Oscilloscope tube with electromagnetic deflection
пK	Cathode ray tube
Type  number	Semiconductor

The fourth (4o) character defines the construction type and material for a device
-	Metal	Applicable to receiving & stabiliser valves
C	Glass
ж	HF glass, side leads
K	Ceramic
п	Miniature glass 19 & 22.5 mm
г	Subminiature > 10 mm
ъ	Subminiature 10mm
P	Subminiature 4 mm
A	Subminiature 6 mm
п	lock-in-key
д	Disc leads
A	Water cooled	Applicable to TX and modulator valves
ь	Air cooled
letter	Phosphor colour code	Applicable to CRT only
X	X = Average current (A) Y = Reverse voltage amplitude (kV)	Applicable to thyratron & rectifier valves

GPO VT NUMBER	CV NUMBER	COMMERCIAL NUMBER
VT17	CV1608	U4
VT19	CV1612	VT9B
VT24	CV1636	LS5
VT25	CV1637	LS5
VT26	CV1600	CAT1
VT27	CV1601	CAR1
VT31	CV1638	4101D
VT33	CV1642	DER
VT34	CV1614	ES1500A
VT35	CV1615	ESU1500
VT36	CV1602	CAR4
VT38	CV1645	E133
VT40	CV1647	LS5B
VT46	CV1616	4104A
VT47	CV1603	4104B
VT50	CV1050	HL2K
VT52	CV1025	DET25
VT54	CV1618	ES250M
VT56	CV1648	4205B
VT57	CV25	4242A
VT58	CV1619	4212E
VT60	CV1605	4013C
VT61A	CV1609	SW7
VT62	CV1606	CAT2
VT65	CV1649	E133
VT66	CV1650	LS5A
VT68	CV1651	G445
VT69	CV1652	P220A
VT74	CV1654	L2
VT75	CV1655	4019B
VT78	CV1656	LS8
VT82	CV1659	4022B
VT83	CV1660	LS7
VT86	CV1662	P215
VT87	CV1663	4021B
VT88	CV1664	4022AR
VT89	CV1665	DH
VT90	CV1732	ML4
VT91	CV1038	MHL4
VT92	CV1735	DC2/P
VT93	CV1666	P610
VT94	CV1667	LS5X
VT95	CV1668	4033L
VT98	CV1669	P625
VT100	CV1040	PX25
VT105	CV1673	HL2
VT106	CV1674	AC/52PEN
VT107	CV1675	N43
VT109	CV1677	PX25
VT111	CV1679	DA30
VT112	CV1680	PM202
VT114	CV1682	PENA4
VT115	CV1683	MP/PEN
VT119	CV1169	VMP4G
VT120	CV1688	4033L
VT125	CV1689	PA1
VT126	CV1690	9A1
VT127	(CV1187)	D41
VT128	CV1692	AC/P
VT131	CV1168	PX4
VT133	CV1695	DDL13
VT136	CV1118	KT2
VT137	CV1081	4052A
VT138	CV1623	RG1-125
VT139	CV399	MH4
VT140	CV1166	LP2
VT143	CV1696	PM2BA
VT144	CV1371	PT6
VT145	CV243	4045A
VT146	CV1625	RG3-250
VT147	CV1697	X41
VT148	CV1698	A819
VT150	CV1699	SP41
VT150A	CV1700	SP41
VT151	CV1701	XLO
VT152	CV1702	XP
VT153	CV1703	XW
VT154	CV1067	L63
VT161	CV1710	6C6
VT162	CV1711	6B7
VT163	CV1712	42
VT164	CV1713	EF8
VT167	CV1716	E1541
VT169	CV1717	4307A
VT170	CV1718	AC/TP
VT171	CV1719	U22
VT177	CV1720	XL 1.5
VT178	CV1721	XP 1.5
VT179	CV1722	A901
VT180	CV1053	EF39
VT181	CV1052	EL32
VT182	CV1723	V257
VT183	CV1724	5A/102D
VT185	CV245	4328D
VT188	CV1727	SP210
VT189	CV1128	GT1C
VT190	CV1728	WE262B
VT191	CV1628	GU8
VT193	CV1100	KTW62
VT194	CV587	DH63
VT195	CV1863	5Z4G
VT196	CV509	6V6G
VT199	CV124	807
VT200	CV1065	SP61
VT201	CV1056	EF36
VT202	CV1054	EB34
VT203	CV9	AL60
VT204	CV18	DET19
VT205	CV1630	ESP450
VT207	CV1091	EF50

KRIEGSMARINE & WERMACHT

These German Eigantum valves carry an alphanumeric code in the sequence: two letters, two numbers, one letter, two numbers.

First letter

R - Reichswehr (Defence) encompassing Wehrmacht  (Army) and Kriegsmarine  (Navy)

Second letter

D - Decametric wavebands
G - Rectifier (Gleichrichter) or diode
K - Cathode ray tube
L - Transmitting or Power
V - Amplifier (Verstärker)

First & second number

Heater voltage

Third letter

A - Cathode ray indicator
D - Dual anode
G - Rectifier or diode
H - Hexode
L - Speed modulation
M - Magnetron
P - Pentode
T - Triode

Final number

Power output (W) or rectifier maximum delivery current (mA).

LUFTWAFFE

These German Eigantum der RLM valves carry an alphanumeric code in the sequence: two letters, one number.

First letter

L - Luftwaffe (German Air Force)

Second letter

B - Cathode ray tube
D - Decametric waves
F - Special type
G - Rectifier or diode
K - Stabiliser
M - Magnetron
S - Transmitting, wavelengths > 1 M
V - Amplifier, wavelengths > 1 M

First  number

Heater voltage

British Army

Comprises of an alpha coding which signifies the valve use or configuration followed by a numeric code that signifies valve.  The most commonly seen are listed below:-

ACR - Army  cathode ray tube
AR - Army receiving valve
ARD - Army receiving diode
ARDD - Army receiving double diode
ARH - Army receiving hexode
ARP - Army receiving pentode
ARS - Army receiving screen grid tetrode
ARTH - Army receiving triode hexode
ARTP - Army receiving triode pentode
AT - Army transmitting valve
ATP - Army transmitting Pentode
ATS - Army transmitting screen grid tetrode
AU - Army Rectifier
AW - Army Stabiliser

British Royal Air Force

Comprises of an alpha coding which signifies the valve use or configuration followed by a numeric code that signifies valve.  The most commonly seen are listed below:-

VCR - Valve cathode ray tube
VGT - Valve gas thyratron
VI - Valve indicating magic eye
VR - Valve receiving
VS - Valve stabilizing neon type
VT - Valve transmitting
VU – Valve rectifying

British Royal Navy

Comprises of an alpha coding which signifies the valve use or configuration followed by a numeric code that signifies valve.  The most commonly seen are listed below:-

NC - Navy cathode ray tube
NGT - Navy gas thyratron
NR - Navy receiving valve
NS - Navy stabilizing neon type
NT - Navy transmitting valve
NU - Navy rectifier

The US Signal Corps, used a numbering system of VT numbers, incidentally, the VT stands for Valve, thermionic – three electrode – a bit of a to do if you want to list a beam tetrode!!!! .  The military look up table MIL-HDBK-213A is required to decode the 289 valves identified in this manner.  However, for the ardent audiophiles, I have prepared this list of the most desired devices:-

VT4C = 211

VT66 = 6F6

VT74 = 5Z4

VT80 = 80

VT94 = 6J5

VT95 = 2A3

VT100A = 807

VT107 = 6V6

VT115 = 6L6

VT126 = 6X5

VT144 = 813

VT145 = 5Z3

VT217 = 811

VT229 = 6SL7GT

VT231 = 6SN7GT

VT197A = 5Y3GT

VT206A = 5V4G

VT244 = 5U4G

Hi peeps,  well, in response to another valve related query, this time about 'JAN codes', I thought I would pen a little information nuggett here today.   I shall be doing a further more detailed  blog entry on military coding history and types soon but for now here's a quick info - bite. 

The JAN code is of course the US Military Joint Army Navy coding introduced in 1942 in which the code for a particular valve type comprises of an alphanumeric code, for example VT-114 and additionally a three digit alpha code.   I will deal with the former in more detail later,  but the alpha code is a manufacturer code.   Here is a short listing of the most commonly seen codes with their corresponding manufacturers:-

CHS – Sylvania
CHY – Hytron or CBS-Hytron
CKR – KenRad
CL – GE
CRC – RCA
CRP – Raytheon

There have been multiple USN numbering systems in use over the years.

The initial numbering system was introduced in 1912 with the first of two letters signifying the device manufacturer followed by a sequentially assigned number to indicate valve type.

A replacement system was introduced in 1932 in which  the two letter device manufacturer code continued but the numerical part was augmented into a 5 digit  number in which the first two designated the valve classification and the successive three the specific type number.

This system was replaced in 1942 using the Joint Army Navy (JAN) system due to a larger range of valve types used in war materiel requiring classification.

As the new scion of Mullard, I have just received by e-mail a question as to whether or not SR Mullard was an unpleasant man to work with.       Many had commented that Stanley was a ‘rough diamond’ with little formal education.     Most of his bad press seems to stem from the contretemps between himself and CO Stanley in the days before CO was the owner of WG Pye.   At this time, Mullard was looking for sales expansion and CO Stanley as the charismatic owner of the marketing agency ARKS, hit upon a grand scheme whereby a new magazine entitled Radio for The Millions would be produced which extolled the great virtues of Mullard’s PM series valves.  

The first edition of the magazine was penned with a range of four tried and tested radio designs which could be built by the home constructor for  as little as two pound and fifteen shillings.     The idea was that funding for the magazine would be sponsored by component manufacturers but they were not particularly forthcoming and Radio for The Millions was majority funded by the Mullard Company.    In a pilot study the initial uptake of this magazine was slow and CO Stanley hit on the idea of advertising in The Daily Mail hence ‘gifting the magazine to the nation’.     All the interested public had to do was write to Mullard House and lo and behold a free copy would be sent to them by return mail.   The only fly in the ointment was the cost of that advert in the Daily Mail which would cost some £900.   Stanley Mullard didn’t want to stump up the dosh but the silver tongued CO Stanley  talked him round.

The Daily Mail advert ran in early December 1926 appearing in a Saturday edition of the newspaper.   Come Monday morning, Stanley Mullard and CO Stanley gathered at Mullard House to see what effect the advert had produced – the post came and went ............and not one single response was received as a product of this expensive advert.      Stanley Mullard, it is said, exploded in apoplectic rage and was said to have roundly cursed CO Stanley in a particularly vile and  vitriolic manner.  This tirade went on for some time and was cut short only by the arrival of a special mail delivery – the response to the advert was so great that the volume of mail could not have been conveyed by a standard mail delivery!!!!!   Stanley Mullard apologised and soon went on to reap the rewards of this campaign by capturing the valve supply for 25% of all radio receivers home constructed during  the 1926 – 1927 financial year.

So, the above example portrays a brusque abrasive chap with a hair trigger temprement, however, it seems he was also capable of great empathy, kindness and concern for his employees.   It is reported that Stanley Mullard spent a lot of time on the shop floor of the Mullard works, always keen to, as Tom Peters would say some 50 years later, ‘manage by walking round.’ Stanley would always listen to his workforce, particularly on advice of how to improve production methods. It is said that his staff were entirely loyal to him and not one employee withdrew their labour during the General Strike of 1926.      Other examples of his empathy were  demonstrated if an employee was found to be not performing, in which case they were give an two week leave of absence, if you had a managerial position, this was expanded to a four week leave of absence.   This philanthropy came at a price as refreshed from your holidays  one was then expected to then step up to the mark!

Some have postulated that Stanley’s lack of formal education was due to a mild form of dyslexia, however, this did not prevent him from running what was to become the largest and most revered valve manufacturer in the UK or once he left Philips-Mullard to become quite a celebrity within the rose and carnation growing circles.  It is said that the Mullard family had a Siamese cat which was fond of – as cats are wont to do – to perambulate, micturate and defecate throughout the garden - even amongst the carnations and other shrubbery  – did our Stanley's  volatile temprement surface and was he ever heard to lustily bellow I’LL KILL THAT COOKING FAT!        To that particular question, this scion cannot comment further.

1957 sure was a busy year as there was much  squabbling and unrest at the Croydon Beddington Lane service facility but by 1958, overcrowding was alleviated by the opening of a satellite service office again in Croydon, just down the road in Purley Way.

In 1959, Blackburn was again visited and a new chemical plant having pilot plant, kilo lab and a four reactor facility was built to allow synthesis of the specialised chemicals utilised in valve and capacitor manufacture.

Well, I have broken off my series of Mullard historical blog posts to answer a query I have received from a customer about the so called Mullard Mustard capacitors.   These capacitors, introduced to the radio market in 1958 have a polyester dielectric which exhibits very low dielectric loss, high insulation resistance coupled with good temperature and moisture resistance.   In all these parameters they far exceed the efficiency of paper dielectric capacitors and impart a very similar audio signature I am told.

Throughout the 1960’s Mullard Mitcham conducted a whole raft of accelerated storage and use testing and found these are ultra stable, ultra reliable capacitors. Indeed ask many service men and they will tell you that never in their career did they need to replace one of the Mullard mustards due to failure in use. It is because of this reliability and  intrinsic audio characteristics that these are sought today for use by audiophiles and guitarophiles ( - is there such a word?).     Actually, the serviceman probably would not refer to them as Mullard Mustards but rather Mullard polyester capacitors  C296A.

I have been asked what these codes mean, well, the prefix C stands for capacitor, 296 is the series type of the capacitor, the series type notation is followed by either  AA for 160V rating or AC for 400V rating.    The coding will then continue in the form C296Ay/xxx. where the first (post slash) letter that indicates the tolerance of the capacitor.  In the case of the 296 series, A = +/- 10%. The numerical component denotes the capacitance value of the device.    Let us use the lowest value available of 0.001uF which can equally be expressed as 1nF.    

This will appear on the device as 1K giving, for a 400V device the full code C296AC/A1K.   Similarly for an 0.033uF 160V device, the full code would be C296AA/A33K.    In the same fashion for a 0.22uF 400V device, the full code would be C296AC/A220K.

In summary, one can always easily read the capacity of the device by considering the letter K to equate to the unit nF and the numerical component to be the value.  To translate an nF value into other units of capacitance, the following conversion factor may be applied.

1uF = 1000nF = 1000000pF

Anyhow, because I am a top geeza, I have produced a table showing the ENTIRE range of C296 capacitors ever made with their corresponding codes and capacitance values in various Farad units - pretty good huh?

TYPE NUMBER	CAPACITANCE (uF)	CAPACITANCE (nF)	CAPACITANCE (pF)	WORKING VOLTAGE  (V)
C296AA/A10K	0.01	10	10000	160
C296AA/A15K	0.015	15	15000	160
C296AA/A22K	0.022	22	22000	160
C296AA/A33K	0.033	33	33000	160
C296AA/A47K	0.047	47	47000	160
C296AA/A68K	0.068	68	68000	160
C296AA/A100K	0.1	100	100000	160
C296AA/A150K	0.15	150	150000	160
C296AA/A220K	0.22	220	220000	160
C296AA/A330K	0.33	330	330000	160
C296AA/A470K	0.47	470	470000	160
C296AA/A680K	0.68	680	680000	160
C296AA/A1M	1	1000	1000000	160
C296AC/A1K	0.001	1	1000	400
C296AC/A1K5	0.0015	1.5	1500	400
C296AC/A2K2	0.0022	2.2	2200	400
C296AC/A3K3	0.0033	3.3	3300	400
C296AC/A4K7	0.0047	4.7	4700	400
C296AC/A6K8	0.0068	6.8	6800	400
C296AC/A10K	0.01	10	10000	400
C296AC/A15K	0.015	15	15000	400
C296AC/A22K	0.022	22	22000	400
C296AC/A33K	0.033	33	33000	400
C296AC/A47K	0.047	47	47000	400
C296AC/A68K	0.068	68	68000	400
C296AC/A100K	0.1	100	100000	400
C296AC/A150K	0.15	150	150000	400
C296AC/A220K	0.22	220	220000	400
C296AC/A330K	0.33	330	330000	400
C296AC/A470K	0.47	470	470000	400

The C296 series of capacitors also carry a three digit batch code of the form A8B

Where digit 1 is the quarter code: - A = January - March; B = April - June; C = July - Spetember; D = October - December.

Where digit 2 is the year code: - 1 = 1961; 4 = 1964 etc....

Where digit 3 is the manufacturing plant: - B = Blackburn; D = Hamburg: S= Barcelona;

Of great concern to Mullard was not only the fact that valve demand had dropped to 50% of it’s wartime peak but also that the cash strapped Government hit on the plan to dispose of their massive war stocks of valves to the ‘radio trade’ at a bargain price of £5000 per million devices. In all, this disposal lasted for ten years after the end of WW2 and in excess of 32 million devices were trickled back for domestic and industrial use in this way.  

To put this into perspective, this mind boggling  number equates to the entire sales of valves made by Mullard during any single year throughout the 1950s!!!!     Add this to the worry that an immediate  post war television boom that never came – at least until 1952 (wonder what happened that year) and you can see why various belts had to be tightened at Mullard.  SS Eriks, General manager of Mullard realised that innovation and product introduction were the key to a successful and stable future, to this end, he arranged for the Mullard Research Laboratories to be built in 1946 at  Cross Oaks Lane in Salfords,  Surrey and thence for the laboratory to be  generously funded. 

1947 also brought some corporate and boardroom shennanigens as Philips Gloilampen Fabrieken (UK) was reorganised into Philips Electrical Industries UK. This had the knock on effect of The Mullard Radio Valve Co. Ltd being renamed Mullard Limited and for the Mullard headquarters to be situated within the Philips Electrical Industries UK headquarters at Century House, Shaftesbury Avenue, London.

 This was followed in 1948 by the renaming of the Mullard Wireless Service subsidiary to Mullard Electronic Products to ensure placement of the Mullard name in areas other than traditional ‘wireless’ manufacturing.  Also in 1948, as a reward for his sterling war effort and his vision of the future, a grateful nation awarded  SS Eriks his OBE.

Thus reorganised,  the Mullard machine marched onwards to face the challenges of the fabulous 1950s.

Valves used by the British military Armed Services were marked with a  CV or common valve name which was defined by the  Inter-Service Technical Valve Committee in 1941.     Often, below the CV number,  a two part  alpha code of the form KB/xx  or JB/xx will be seen  which gives the devices manufacturing specification and qualification .  For the first part of the alpha code, the K designates a valve manufactured to specification K1001 or K1006; similarly a J designates a valve manufactured to a JAN or MIL spec.  The second letter of the first part of the alpha code describes the qualification approval the valve type has, a B denotes qualification by a UK authority, a U denotes US qualification,  a D  denotes Australian qualification and an X  denotes Director of Electronics Research and Development  (DERAD)  approval.

The second part of the alpha code identifies the factory that manufactured the  device, the most commonly seen codes and their corresponding manufacturers are:- 

A	Mullard, Blackburn, pre Jan 1951
A	Thorn, Tottenham, pre April 1964
AB	Sylvania-Thorn, Enfield
AC	Brimar - Thorn-AEI, Footscray
AD	Brimar - Thorn-AEI , Rochester
B	Edison Swan, Baldock, pre Sept 1945
BA	AEI, Woolwich
BC	Joseph Lucas, Birmingham
C	Edison Swan, Ponders End, pre Sept 1951
CC	Cathodeon, Cambridge
CE	20th Century Electronics, pre  March 1957
CF	20th Century Electronics, New Addington
CN	Pye Industrial Electronics
CO	Newmarket transistors, Newmarket
CS	Cathodeon, Southend
D	Mullard Radio Valve Co., Mitcham
DA	Mullard Radio Valve Co., Blackburn
DB	Mullard Radio Valve Co., Salford
DC	Mullard Radio Valve Co., Whyteleafe
DE	Mullard Radio Valve Co., Fleetwood
DF	Mullard Radio Valve Co., Waddon
DG	Associated Semiconductor Manufacturers, Southampton
DH	Societe Anonyme Philips, Brive, France
DJ	Wiener Radio Werke, Abbeygasse 1, Vienna
DK	Philips GMBH, 140 Ebentalstrasse, Klangenfurt
DL	NV Philips Gloeilampenfabrieken, Nijmegen
DM	NV Philips, Stakskanaal, Holland
DN	La Radiotechnique, Caen, France
DP	Valvo GMBH, Hamburg, Germany
DQ	Philips SpA, Milan, Italy
DR	Philips AG, Zurich, Switzerland
E	Thorn-AEI, Brimsdown
EA	Edison Swan, Ponders End
EB	Edison Swan, Gateshead
EC	Edison Swan, Tottenham
EN	Thorn-AEI, Sunderland
F	STC, Paignton
FB	STC, Footscray
FC	STC, Lorenz,. Esslingen, Germany
FD	STC, Rochester
FDA	Alexandria, NSW, Australia
FE	STC, Oldway (Additional to Paignton factory 'F')
FF	STC, Harlow
G	Ericsson, Beeston
GA	(Ericsson), AB Svenska Elektronror, Stockholm, Sweden
H	Hivac, Harrow
HC	Hivac, Chesham
HR	Hivac, Ruislip
J	STC, Crewkerne, pre Jan 1946
J	Radar Electronic Equipment
JA	SGS Fairchild, Ruislip
JB	SGS Fairchild, Agrate, Milan, Italy
JD	Elliott Bros. (London) Ltd, Borehamwood
JE	Elliott-Litton, Borehamwood
JK	La Radio Technique, Suresne, Paris, France
JN	International Rectifier Co., (GB) Ltd, Oxted
JQ	Associated transistors, Ruislip
JT	Microwave Associates Ltd, Luton
K	Electronic Tubes, High Wycombe
L	CSF, Levallois-Perret (Seine), Paris, France
L	MOV Highgrove pre Oct 1951
LB	CSF, St. Egreve, Grenoble, Isere, France
M	Gramophone Co., Hayes
MA	EMI research labs, Hayes
MB	EMI research labs, Ruislip
ME	EMI, Hayes
MR	EMI (Valve Division), Ruislip
MT	EMI, Treorchy
N	Nore Electric, Southend
N	STC, Footscray, pre August 1951
NP	Texas Instruments, Dallas Road, Bedford
NQ	Texas Instuments, Bedford
NR	Texas Instruments, Nice, France
O	Rank Cintel, Lower Sydenham
OR	Rank Cintel, Rotunda
OS	Rank Cintel, Sidcup
P	Philips, Eindhoven, Holland
P	GEC, Shaw, pre August 1948
PA	Philips Teleindustri, Stockholm, Sweden
PDA	Philips, Hendon, Australia
Q	English Electric Valve Co., Chelmsford
QB	Marconi Wireless Telegraphy Co., Great Baddow
QC	Marconi Wireless Telegraphy Co., Chelmsford
QD	English Electric Valve Co., Stafford
QE	English Electric Valve Co., Kidsgrove
QF	English Electric Valve Co., Nelson Research Labs, Hixon
R	Ferranti, Moston
R	Ferranti, Gem Mill Oldham, pre July 1947
RA	Ferranti, Edinburgh
RB	Ferranti, Dundee
RC	Ferranti, Chadderton, Oldham
S	AEI, Rugby
SA	AEI, Lutterworth
SB	AEI, Lincoln
SC	CFTH, Usine de Joinville, Seine, france
SD	SESCO, Rue de L'Amiral, Mouchez, Paris, France
SDA	Amalgamated Wireless, Australia
SF	CFTH, Rue Mario-Nikis, Paris, France
SL	AEI, Leicester
SP	AEI, Peterborough
T	British Tungsram, Tottenham
U	MOV, Bulmer, pre Oct 1945
U	Nucleonic and Radiological, Stratford
V	Cossor, Highbury, pre Sept 1945
V	Gilbert Photoelectrics
VA	Westinghouse, Chippenham
VF	MCP Electronics, Alperton
VL	Hughes Internations (UK) Ltd., Glenrothes
VR	Brush Rothermell Crystal Co., Hythe
W	GEC, Hirst Labs, Wembley ASM Ltd
WB	GEC, Coventry
WD	Claude General Neon Lights, Wembley
WE	ASM Ltd, Hazel Grove
WF	ASM Ltd, Broadstone
X	MOV, Springvale, pre Oct 1951
Y	MOV, Moray, pre April 1945
YA	Leigh Electronics, Havant
YC	Semiconductors Ltd., Cheney Manor, Swindon
YD	Semiconductors Ltd., Towcester
Z	MO Valve Company, Hammersmith
ZA	MOV, Gateshead, pre March 1957
ZB	MOV, Perivale
ZC	MOV, Springvale, pre August 1957
ZD	MOV, Dover, pre Dec 1956
ZE	Osram GEC Lamp Works, MXT Dept, pre March 1957

 In a separate cartouche there often is a two character alpha code which denotes manufacture date   eg AA.    The first letter denotes the year and uses the entire alphabet except for I and O  and started in 1945.  Hence an  A denotes 1945 and Z denotes 1969.    In a similar fashion the second letter denotes the month of manufacture with A  denoting January and M denoting December.

An additional system of dating is also used which records the date of valve labelling, this dating system utilises a four digit numeric code in which the first two integers denote year and the second two integers the week of the year.   Hence 6712 would denote March 1967.

.

As if that wasn't enough, the jolly Germans had a crack at the Mitcham site, first of all in October 1940 when a stick of bombs hit the New Road site towards the rear of the complex which resuted in the total destruction of a machine shop.  Many wags said that this was no great shakes and that Mitcham should be thankfull than the nearby marzipan factory of Renshaws was spared bombing!        The next attempt was a hit purely by fluke as a V1 Flying Bomb belted a buliding again towards the rear of the complex in  June 1944.   The nose cone of the V1 was found in the nearby Wandle river and rescued as a trophy by a group of local children - I wonder if it still survives today?

SS Eriks decision to transfer much of valve production to Blackburn was vindicated as the Mullard Blackburn facility was never bombed, even though the first bombs hit Blackburn residential areas in August 1940.   Strangely enough, Lord Haw Haw, Nazi propagandist and radio broadcaster continued to warn the people of Blackburn that the Nazis were aware of the local Royal Ordinance Factory locations and bombs would follow but Blackburn remained unharmed.  It is interesting that the Nazis either didn't know about or chose to ignore the Mullard Blackburn facility. 

An interesting aside is that a single V1 Flying Bomb hit Hoghton on the outskirts of Blackburn on Christmas Day 1944 - was it just off course or was it an attempt to give Mullard Blackburn a Christmas present?    It's a real enigma as gyroscopic control kept all of he V1 flying bombs on their launch preset course and a turbine dynamometer situated in the nose cone of the V1 cut the fuel supply and hence stopped the pulse jet engine after a preprogrammed distance had been travelled the result being that 15 seconds later the V1 came to earth with a big kaboom.  So why was Lancashire chosen - did the gyroscope wobble the V1 away from the Home Counties or was the V1 deliberately set on a Lancashire trajectory?

To put the V1 Flying bombing of Mullard facilities into perspective, the statistics are quite interesting - 2 V1 flying bombs out of the 8025 fired in total hit Mullard facilities.     1,126,998 premises other than Mullard facilities were damaged or destroyed by V1 flying bombs.

It is interesting to compare the performance of Mullard Mitcham and Blackburn during the war years, figures from 1944 show that Mitcham produced 5 million valves whereas Mullard produced 6.5 million - not bad for this six year old site!    Part of this was due to the more modern production techniques ad equipment at Blackburn and  part also to the larger staff quota - in 1944, Blackburn had 4185 staff on site.   

Mullard valve manufacture was perceived by the government of the day as essential war work and if we compare Mullard's manufacturing to the traditional industrial mainstay of Blackburn, cotton manufacturing,  some interesting facts and statistics are revealed.  It's quite ironic that the latter suffered as a result of the former!    Govenment policy was quite adamant that it was essential to release as many indigenous workers as possible for war production which had the effect of concentration in Blackburn (and much of Yorkshire & Lancashire)  whereby many cotton mills were closed down until the number of active cotton mills in Blackburn dwindled from the peacetime level of 64 to just 19.  The surviving mills found themselves engaged on the production of such unfamiliar fabrics as parachute cloth (- not very successfully as the machines were outdated and unsuitable), camouflage material, and khaki drill.   The empty mills were used for storage of food supplies or strategic material as Government Storage Depots or Buffer Depots.   During the "Blitz" two mills were used to rehouse firms whose premises had been bombed.

Like it's contemporary, the Acorn valve, the EF50 was very different from any valve Mullard had manufactured previously.   It needed a skilled labour force, new equipment and instrumentation and the consistent application of hitherto unknown manufacturing techniques because in the EF50, the traditional micanol base was replaced with a 'disc seal' glass base which required, special manufacturing equipment, special glass and three types of special wire!!!!!   

Early attempts at base manufacture were catastrophic, mindful of waste, the winds of war circulating Europe and the shame of being looked down on by Philips management, Dr E A Roberts of Mullard Blackburn was seconded to the Emmasingel development laboratories of Philips Eindhoven in February 1940 to perfect the required glass forming techniques.   In May 1940, as the Panzer tanks rolled into Holland, the good Doctor made good his escape from Holland by hitching a lift  on a passing British destroyer.   Thankfully, he carried a briefcase stuffed full of drawings, formulae and information on glass forming but more importantly, he had helped broker a deal with Philips Eindhoven to supply 25,000 completed EF50 devices and 500,000  pre - formed EF50 bases that would jump start the bulk manufacture of EF50 valves in England and these were shipped on the 9th of May 1940 by road freight and thence a Zeeland Steamer Company ship.  After a harrowing journey in which the ship was attacked and damaged by Stuka dive bombers, the ship with it's precious cargo arrived safely in England, six days later - a few days after Dr Roberts' escape.   With both man and materials safe, Mullard and the EF50 went on to play a pivotal part in the Allies' success, so much so, that the EF50 was crowned ' The Valve that Won the War!' but more on that particular story in a future blog entry!

I have taken Stephen to task for his meddling in renaming Guy Gibson's beloved pet, why should we rewrite history for the sake of political correctness -  history is inviolate!  Anyhow, we were fortunate enough to meet one of the stars of the new film when we were fitting out the R1155/T1154 station.  Remember, you saw it here first, direct from the Boreham Wood studios, I bring you this picture of Tigger,  Guy Gibson's beloved cat  gambolling inside a T1154 casing.

Eriks was a chap whom melded humanitarianism with good business acumen, the Mitcham site could not be expanded further, what he needed was an available work force and a surfeit of cheap plentiful land upon which to build a new plant yet still have plenty of room for future expansion.     Eriks hit on the idea of building his satellite plant 'uuup north' and he chose Blackburn in Lancashire as a good location.  You see,   due to the decline of the cotton industry there was a sizeable unemployed workforce of mainly dexterous women, freely available and even quite a few chaps too with collarless shirts and big flat caps.   Remember, that part of Lancashire was a depressed area in the 1930s, with no nipping out to The Three Fishes, Ferraris or The Calves Head for a gastro meal - you were lucky if you got stew & hard and that's a Burnley delicacy really.  Accordingly, the foundation stone for  the Blackburn plant was laid on 30th March 1938 and a new era dawned for Mullard.  

Eriks viewed his empire with puzzlement, efficiencies in manufacturing had been taken as far as they could but by 1937 it was evident that more production capacity than Mitcham could supply was required, the problem was, what could be done?

With Philips now owning all of the shares in Mullard, change was looming as although Stanley was kept on as MD, he was put firmly in the picture that Philips was now firmly in control.  In 1929 when Stanley floated the idea of Mullard diversifying into receiver manufacture, Anton Philips gave him the hard word and refused.   As if this rebuttal wasn't enough, Anton Philips then  despatched a 26 year old wunderkind engineer in the form of Wim Julius to modernise the Mullard factory.   Stanley Mullard realised it was time to move on and in 1930 he resigned from Mullard Valves to spend more time cultivating roses which were his passion.   In later years, Stanley was heard to muse that he made more money from horticulture than he ever made from electronics.  In fact he was responsible for using vermiculite in potting mixtures as this mica derived material was used to pack the mica stacks bought in for valve manufacture - was this an early example of green recycling I wonder? - whatever, please remember this interesting fact the  next time you are buying vermiculite at Dobbies or Wilkos!!

 The Monk & The Cat ;   Samuel Barber. 

But hey, don’t take my word for it, why not buy some Pussy treated valves for me and try them yourself – look for the PMT (Pussy Manufacturing Technology) valve range in our product listings. And remember, using my super website review facility you can tell everyone else what you think – wowser!

 

Kirlian photography can show up these forces, emanating from the Pussy as you can see in this Kirlian photogram of Noctode below.   I should like to stress that Kirlian photography is a real technique and is in no way related to the fact that the first Devon Rex cat was called Kirlee or because all Devon Rexes have curly fur. Trust me, I am a scientist and pseudo-scientific psycho babble when applied in an audiophilic sense - just like in the hifi comics, sorry, hifi magazines - means that all I am telling you is true – cross my heart and hope to find a PX25! 

 Noctode is not fazed by Pussy treatment and takes her work very seriously, here you see her viewing the fruits of her labour on our AVO VCM Mk2. – her paws are too small and delicate to use the controls on our mighty VCM163.  Isn’t it sweet how she is using her tail here to adjust the mA/V control whilst nonchalantly posing for the camera.

Now the Mullard Magic website is up and running, we have explained to Noctode that we will need her to treat more valves so she has been busy training at our local pussy gym - here you can see her in action.

So there you have it, Pussy treated valves in a nut shell, next time,  I will bring you the results of an exciting comparative listening test between cryo treated, Pussy treated and mis - sorry untreated valves

Anyhow, I digress, because as a PhD qualified scientist armed with a Bash Street Swimming Club 100M swimming certificate and a Swiss Army knife having an attachment for removing stones from horse hooves, I have devised a new post manufacture valve treatment, yes, Pussy treatment and I will be offering it free of charge, on request to anyone who purchases any valve I offer for sale.

Original valve box images  by kind courtesy of Alan Wyatt of The National Valve Museum = see more at www.r-type.org

Am I just being silly, shall we place this myth iof special Mullard electrons 'in the file box' along with wood capacitors, CD felt tip pens, solid silver mains leads plaited by virgin Cuban nymphs specially selected for the tightness of their (ooo-eer) cigar rolling... and other audiophillic pseudo scientific quackery.

Original valve box images  by kind courtesy of Alan Wyatt of The National Valve Museum = see more at www.r-type.org