batch-testing 6sn7 with Hickok 533a

[Patrick]

I constructed an adapter to batch-test 6sn7 or 6sl7 with a Hickok 533A
I compared the results of a tube in the batch with these of a single tube in
the tube tester.

The values are somewhat lower e.g. 2950 micromohs becomes 2900micromohs. I
wonder how that comes.

Can it have something to do with the heater circuit?

The adapter holds 12 sockets with all filaments connected in parallel to a
powerfull filament transformer. All cathodes and grids are connected
together and to the proper tube tester socket pins.
The test lead is connected to the anode circuit at the tube tester.
After letting the tubes heat up, the transconductance of each triode can be
measured fast by contacting the anode one by one.

The links below point to a few pictures of the setup:

http://users.skynet.be/m28/TubeGallery/Images/08160005.JPG

http://users.skynet.be/m28/TubeGallery/Images/08160006.JPG

Thanks for any advise.

Patrick

[[email protected]]

Patrick wrote:
> I constructed an adapter to batch-test 6sn7 or 6sl7 with a Hickok 533A
> I compared the results of a tube in the batch with these of a single tube in
> the tube tester.
>

Looks like with the proper lash-up, you could bulk test about any
octal-socket tube that way. I do not see that the 533A has matching
capacity, but that system would even work with a tester so-equipped.

Peter Wieck
Wyncote, PA

[Patrick]

> schreef in bericht
oups.com...
>
> Patrick wrote:
>> I constructed an adapter to batch-test 6sn7 or 6sl7 with a Hickok 533A
>> I compared the results of a tube in the batch with these of a single tube
>> in
>> the tube tester.
>>
>
> Looks like with the proper lash-up, you could bulk test about any
> octal-socket tube that way. I do not see that the 533A has matching
> capacity, but that system would even work with a tester so-equipped.
>
> Peter Wieck
> Wyncote, PA
>
I have tested 12 double triodes in the time needed for one with this
fixture. It works great.

For penthodes and beam power tubes I think a second testprobe to grid2 would
be necessary.
And for multigrid tubes as well...

[robert casey]

Patrick wrote:

> I constructed an adapter to batch-test 6sn7 or 6sl7 with a Hickok 533A
> I compared the results of a tube in the batch with these of a single tube in
> the tube tester.
>
> The values are somewhat lower e.g. 2950 micromohs becomes 2900micromohs. I
> wonder how that comes.
>
> Can it have something to do with the heater circuit?
>

I've seen grid stoppers used in some setups like this. To avoid any
chance of a tube going into oscillation.

[Patrick]

"robert casey" > schreef in bericht
ink.net...
> Patrick wrote:
>
>> I constructed an adapter to batch-test 6sn7 or 6sl7 with a Hickok 533A
>> I compared the results of a tube in the batch with these of a single tube
>> in the tube tester.
>>
>> The values are somewhat lower e.g. 2950 micromohs becomes 2900micromohs.
>> I wonder how that comes.
>>
>> Can it have something to do with the heater circuit?
>>
>
> I've seen grid stoppers used in some setups like this. To avoid any
> chance of a tube going into oscillation.

I just checked a batch of 12 6SN7GT tubes with this setup (adapter + Hickock
533A), while monitoring the anode voltage with a Tektronix 2445B 150MHz
oscilloscope. None of the triodes showed signs of oscillation.