[R-390] R-390A tube adapter

[Jerry O. Stern]

Lots of tube adapters on Ebay with 7, octal and 9 pin and with tube pin test
points as well.. best quality bakelite made by vector and pomona.  Be
careful to get the skinny versions as the standard 7 and 9 pin are too fat
to fit inside a tube base with integral shield sleeve.

Jerry
K1JOS

-----Original Message-----
From: r-390-bounces at mailman.qth.net [mailto:r-390-bounces at mailman.qth.net]
On Behalf Of 2002tii
Sent: Tuesday, February 22, 2011 1:54 PM
To: R-390 at mailman.qth.net
Subject: Re: [R-390] R-390A tube adapter

Tisha wrote:

>The tube adapter is really an extender so you can access the pin
connections
>on a tube base to measure voltages or resistances.
>
>They are homebrew devices with a pin base and a socket, attached with
fairly
>inflexible wire so you can raise the height of the tube up to a point where
>you can get to the individual pins (little loops or taps to connect at the
>top tube socket.

Back in the day, tube extenders were made commercially.  Some 
examples can be seen at:

http://k4che.com/tube%20extenders/TUBE%20EXTENDER%20PAGE%201.htm

For equipment like the 390/390A, where the bottoms of many tube 
sockets are inaccessible without disassembly (and even if you 
disassemble, it is often difficult to operate the disassembled radio 
unless you have extender cables), tube extenders can be very useful 
in troubleshooting faults.  IME, tall ones are often better so that 
the test point contacts are more likely to clear IF cans and other 
things mounted near the tube sockets in densely-packed chassis.

Best regards,

Don


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