[R-390] Tracking down low sensitivity 0 to 8 mhz problem

[Larry H]

Hi Jordan,  Are you using a high impedance vtvm to measure it at E209?  It
must be and the 390 must be in standby.  Also, if you measure it at J221,
what you connect to it will probably detune T207 and change the output,
sometimes quite a bit.  And, what are the dc voltages on the mixer plate
and cathode in AGC mode?  You can use a tube test extender to measure
them.   You might want to scope the cathode while it's in there and see
what it shows.   In the past, I've found that the mini coax to J221 can be
bad or the connection from J221 to P221 is bad (try exercising the
connection a few times).  Or C277 could be bad.  And, what are the dc
voltages on the osc plate and screen?

Have fun.

Regards, Larry

On Sat, Mar 30, 2024 at 7:59 PM Jacques Fortin <jacques.f at videotron.ca>
wrote:

> Ok Jordan, let us know what you found.
> If ever you doubt about the T207, I still have some spares...
>
> 73, Jacques, VE2JFE in Montreal
>
>