[ARC5] T-22 Woes

[Mark K3MSB]

Thanks for the reply guys.

I was measuring the plate voltages on the tube anodes.  This tells me RL-50
& RL-51 (the suppressors), R-76, and L-53 are OK.

I replaced C-72 which didn't help.

I did zorch my relay in the power supply (it's the one from the modulator
unit) so I'm having to work at lower plate voltages until I can get a
suitable replacement relay.   I'm not using the keying and voltage divider
network as per Dave's article (and the manual).

As an aside, there is very little chirp on my 80M T-19 with it being keyed
as per the manual.

I now have good screen voltage.  Don't ask me why.   I did go around and
resolder joints  after that happened.

Before the relay went and I was running about 550V on the plates,  I was
getting 320V on the screens and about -45 to -50 on the grids.  Nothing on
the output.

Noe that I'm using a temporary relay I'm running with 350V on the plates.
This gives me   -25 on the grids,  225 on the screens, and an Ip of 130
mA.  No output.

If I'm getting good voltages on the grid,  that's telling me I'm developing
sufficient drive from the oscillator (across R-74).

If I'm getting good grid, screen and plate voltages, drawing 130 mA of Ip,
and I replace just about all the parts from the tubes to the
output..........What is left to replace?   I'd pull some hair out but I
have little enough as it is.

73 Mark K3MSB







On Tue, Jun 11, 2013 at 5:18 PM, <WA5CAB at cs.com> wrote:

> A likely culprit for this would be the two parasitic suppressors inside the
> plate tank coil.
>
> In a message dated 06/11/2013 15:44:53 PM Central Daylight Time,
> kgordon2006 at frontier.com writes:
> > Mark: I still suspect that your plate voltage is "missing". Where did you
> >
> > measure this? If not directly at the tube plate connection, it still may
> > be
> > missing.
> >
> > One thing that makes me suspect this is that your screen voltage is low,
> > which indicates excessive current draw, which usually only takes place
> > when
> > the plate voltage is missing.
> >
> > It is certainly possible that the RF connection between the plates and
> the
> >
> > tuning network is also open, but that seems to be less likely.
> >
> > Ken W7EKB
> >
>
> Robert Downs - Houston
> wa5cab dot com (Web Store)
> MVPA 9480
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