[R-390] Pulling tubes, troubleshooting RF deck

[Larry H]

Hi Bill,  Looks like you've narrowed your problem down to the vfo not
getting to the 3rd mixer.  My suggestions  would be to verify the filament
is getting voltage, a contact on the tube or socket is not bad, tube is
good, and connection to mixer is good.

Regards, Larry

On Thu, Jan 6, 2022 at 2:58 PM Bill Kulze <wak9 at cornell.edu> wrote:

> Hi, long time list member, haven't posted a thing in years. Interesting
> about the tubes in tight spaces topic. My 390a has been stored away for a
> while, haven't done anything with it until a week or so ago. No output.
> Tested all the tubes on the RF deck, test good, probably same tubes in
> question. I could get fingers on them, not necessarily both on the same
> hand, lol, but not much grip and took lots of wiggling. I need to clear off
> more space to work on it. I can inject 455kHz to the IF deck and get
> output. I can inject 455kHz at E211 and hear it. I see no output from the
> pto with a scope at the end of the cable, and I can inject 2MHz to 4MHz
> into the RF deck from a generator and there is no output. Still checking
> voltages at the tubes, but haven't had a chance to get too far yet or check
> resistances. Reg 150v is good, filament to pto is good. I don't see very
> much drop in the B+ to the pto, wondering about that. The osc inj voltages
> at E209 and E211 are not what they should
>   be, can't recall right now, but at E210 it was good. Seems like E402
> wasn't right, but like I said, I need to make some bench space so I can dig
> a little easier. In the meantime, if this rings a bell for anybody... ; )
>
> Thanks, nice to see this list keeps going.
>
> Bill W2NVD
> USAF, Ground Radio school at Keesler, spring '77.
> Back when they fogged the Triangle with DDT at night for the skeeters.
> I'm sure there's a few more out there.
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