Help: How to test 4-pin tubes on B&K 747 tester?

[Dave]

Seems to me there must be someone out there who has
come up with a chart of settings for testing the old 4, 5, and
6 pin tubes on a B&K 747??

The 747 is a good tester, but does not have 4, 5 and 6 pin
sockets. I oughta be able to make an adapter up that will
plug into an octal socket and then dial in settings that will
give at least a basic test of the 'old' tubes. I'm sure that
someone sometime has done this......

Any help out there? I'd sure appreciate it.....

Dave WB7AWK
unsolic...@hotmail.com (my 'spamable' address!!)

[Kenneth Scharf]

Dave wrote:

In many cases there are octal versions of old 'standard base' tubes, so
you would just use the settings for the octal versions (translating the
pin numbers). For example 6A7=6A8, 78=6K7, 42=6F6 etc....

[michael Mueller]

Does any one know where this list of modern substiutes can be found?
Thanks Mike M

[Richard S. McCown]

Here are some,
http://www.vacuumtubesinc.com/info3.html

[Bonita Lee Geniac]

Dont know that I have ever seen such a list, but most of the old-timers
know which tubes are the same with different bases. But the RCA tube
manuals from the 1950's in particular often make reference to which
tubes are electrically similar, if you looked up a 41 for instance, it
would give you the basing diagram for it and say the characteristics
were similar to a 6K6, and you would then have to look up the 6K6 to get
more information. Some of the more common equivalents found often in
vintage radios are 41=6K6, 42=6F6, 6A7=6A8, 6C6=77=6J7, 6D6=78=6K7,
75=6Q7=6SQ7, 80=5Y3, 5Z3=5U4, 76=6P5, 25Z5=25Z6, 43=25A6.
If you wanted to make up an adapter for the tube tester, all you would
need to do is take an old octal tube base and wire the 4, 5, 6, and
large 7 pin sockets to it, connecting pin 1 to 1, 2 to 2, and so on. It
would be easier and neater to mount the sockets on a minibox or similar.
Then you would have to use both a tube manual to know which pin of the
old tube was equal to the new tube you were testing it as and make the
corresponding changes when setting up the tester to get the tube
elements on the right pins.

michael Mueller wrote:
>
> Does any one know where this list of modern substiutes can be found?
> Thanks Mike M

--
I don't know Jack Schitt, but once I met Diddley Squatt !!

If "nospam" appears in email address, please remove it to reply

[Kenneth Scharf]

Bonita Lee Geniac wrote:

> Some of the more common equivalents found often in
> vintage radios are 41=6K6, 42=6F6, 6A7=6A8, 6C6=77=6J7, 6D6=78=6K7,
> 75=6Q7=6SQ7, 80=5Y3, 5Z3=5U4, 76=6P5, 25Z5=25Z6, 43=25A6.

Actually the 6Q7 is NOT the same as the 6SQ7 though they do serve the same
purpose. The 6SQ7 has a higher mu
(100 vs 70) than the 6Q7 and they don't test the same in a tube tester.
The 6Q7 is the octal equal of the 75.

Other similar tubes 30=1H4G, 6P7=6F7, 6A3=6B4G, 19=1J6G