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Unwanted 8-pin mini rimlock valves UF42, EF42, ECH42
Unwanted 8-pin mini rimlock valves UF42, EF42, ECH42
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Old 8th July 2018, 09:16 PM   #1
multi-volti is offline multi-volti  United States
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Default Unwanted 8-pin mini rimlock valves UF42, EF42, ECH42

I didnít count pins but today discovered the plastic sockets I tossed yesterday were not 9-pin mini but 8 pin rimlock.

Today I found the used Valvo tubes they held.

Valvo a pai of UF42, an EF42, and an ECH42..came out of a very old pre-WWII dielectric analyzer, which disintegrated (with some help) years ago... curious how old...have 4-letter codes below pnís, and black info under base...

I thought it was odd all three types of tubes had the same numerals with different prefixes, but there is probably a reason other than OCD. Iíd ask why, but think I lost interest since starting this post.

So now to offer them free to a good home, do I have to move this to Swap Meet?
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Old 9th July 2018, 09:35 AM   #2
DF96 is offline DF96  England
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UF42 and EF42 are probably the same apart from heater voltage. ECH42 just happens to be about the same era. They would all have to start with '4', as that indicates the base.
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Old 9th July 2018, 09:54 AM   #3
JonSnell Electronic is offline JonSnell Electronic  United Kingdom
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ECH* is a Triode Hexode. UF*/EF* is a pentode.
U type valves have a 100mA heater, in the case of UF42 21volts. E type valves denote 6.3v heaters.
FYI;

The UCH42 is an early all glass triode hexode from 1948 and was designed as oscillator and mixer for superhet receivers, and the hexode section was designed to operate with an AGC control voltage. The 100 mA heater was intended for universal (AC/DC) sets, and this explains the low anode voltages. Mullard do not give a frequency range for this device, it is, therefore unlikely to be greater than HF as the valve predates VHF broadcasting by more than a decade. Mullard also say that the UCH42 may be used as a phase inverter. The ECH42 does the same job but with higher anode voltages and lower current.

The triode oscillator had to supply a peak to peak insertion voltage of 13 Volts.
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Old 9th July 2018, 12:17 PM   #4
multi-volti is offline multi-volti  United States
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Thanks, both.

I don’t think it’s as old as it looks...has Ruwido pots (gray pot metal ‘23’ bodies, flat riveted back covers with integral ‘ground’ tab on back. If it’s the same Ruwido founded in Austria in 1969...that doesn’t explain ‘Made in Germany’ & ‘Germany’ on other components...a lot of decades between de- & re-unification.

Some Elkonda capacitors have a DIN spec on them that was retired long ago.

Kopf air variable trimmer capacitors were another item observed, but I dead-end on that name.

Anyway, the hammertone green cabinet will house a tube amp some day.

HF sounds familiar...I vaguely think I got the idea it ran in the teens of MHz and there was nothing that looked like VHF layout to me. 50 pF trimmers probably more suited to HF, too.

Nothing but curiosity at this point...
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Last edited by multi-volti; 9th July 2018 at 12:21 PM.
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Old 9th July 2018, 01:39 PM   #5
DF96 is offline DF96  England
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According to this site the ECH42 first appeared in 1948, so it cannot have been part of a pre-WW2 item. Early 1950s is more likely, as by the mid and late 50s the '4x' range had largely been superseded by the '8x' range of 9-pin valves.
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Old 9th July 2018, 04:57 PM   #6
multi-volti is offline multi-volti  United States
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Thank you.
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Old 9th July 2018, 05:16 PM   #7
pcan is offline pcan  Italy
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Unwanted 8-pin mini rimlock valves UF42, EF42, ECH42
Immediately after WW2, it was not uncommon to build things with a mix of old and new components. As example, on my 1948 French Radiola push-pull amplifier the output tubes have the pre-war Europe side contact base, the rectifier has the even older 4 pin Europe base, the phase inverter is a frequency-converter triode/hexode wired in a creative way, and the preamp tubes have a Rimlock base (EF40). The volume potentiometer is clearly pre-war and the chassis is a strange cast aluminium part that seems to have been adapted from some areonautical military application/surplus.
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Old 9th July 2018, 06:50 PM   #8
PRR is offline PRR  United States
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Quote:
Originally Posted by pcan View Post
Immediately after WW2, it was not uncommon to build things with a mix of old and new...
I have a 1948 Zenith radio with an Octal, two Loktals, and a couple Miniatures.

Best radio in the house, FWIW. Pulls-in Boston clear, and NYC after dark listenable; all other radios just buzz except 3 local stations.
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Old 10th July 2018, 09:25 AM   #9
Kay Pirinha is offline Kay Pirinha  Germany
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Quote:
Originally Posted by multi-volti View Post
Kopf air variable trimmer capacitors were another item observed, but I dead-end on that name...
No wonder. The - now extinct - company's correct name was Hopf.

Best regards!
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