[Amps] Suggestions - I broke my amp - part 2

[Gary Schafer]

If the output relay was open there would be a large dip in plate current
when the tune control was tuned with drive applied.

Open bandswitch or switch on the wrong band is most likely. Try another
band.

73
Gary  K4FMX

> -----Original Message-----
> From: amps-bounces at contesting.com [mailto:amps-bounces at contesting.com] On
> Behalf Of n8de at thepoint.net
> Sent: Tuesday, November 16, 2010 7:53 PM
> To: Larry; Larry
> Cc: Amps
> Subject: Re: [Amps] Suggestions - I broke my amp - part 2
> 
> One thought:
> 
> Have you checked the output relay to see if it makes contact when fired?
> 
> If the output of the amp wasn't making it to the antenna, the symptoms
> you describe would be happening.  No RF getting past the relay due to
> the relay NOT closing properly would give no output to your RF meter,
> right?
> 
> 73
> Don
> N8DE
> 
> 
> Quoting Larry <lknain at nc.rr.com>:
> 
> > A number of you offered suggestions a couple of weeks ago and I checked
> those
> > suggestions a couple of times. I have finally got back to trying to
> > track down what
> > is probably a silly error on my part that has broken my
> > Clipperton-L. The mods were
> > triggered by the destruction of the original parasitic suppressors.
> > The amp was
> > working - just not well in all conditions.
> >
> > I  replaced the power supply board (just an upgrade to better
> > supply), replaced the
> > plate RFC to an Ameritron AL-572 RFC along with the parasitic
> > suppressor board,
> > changed the plate bypass cap at the power supply side of the plate
> > RFC to a 0.002uf
> > value, changed the plate blocking cap to 0.002uf, changed the
> > filament RFC to a
> > bigger unit, and changed a couple of doorknobs for 160 (unrelated to
> >  the original
> > problem of the parasitic suppressors). I haven't gotten to 160 yet.
> > The current effort
> > is using 40. The current result is still no output
> >
> > 1. There is plate current (as measured by the panel meter) and there
> >  is plate voltage.
> >
> > 2. I don't have a HV probe but I could measure at the plate  voltage
> >  (at the plate caps)
> > as the voltage was dropping after turning off the power switch and
> > it tracked with the
> > panel meter.
> >
> > 3. The idle current seems OK.
> >
> > 4. The plate current follows keying. The plate current changes as it
> >  should as the driving
> > power is increased or decreased.
> >
> > 5. Adjusting the output cap controls has no noticeable effect on the
> >  plate current (no dip
> > etc).
> >
> > 6. Using an ohmmeter there is continuity (short) from the output
> > network side of the plate
> > blocking cap (on the cap lead) to the output connector. From the
> > other side of the
> > plate blocking cap (on the cap lead) to the power supply there is
> > continuity (short).
> > Thinking perhaps the new blocking cap might be bad I replaced it
> > with a pair of 0.001uf
> > in parallel but still have the same result. (I remeasured the shorts
> >  after replacing the
> > blocking cap.)
> >
> > 7. The output relay is switching as it should. None of the wiring to
> >  the relay was touched
> > in this mod.
> >
> > It has been a long time since I worked on an amp. I am sure I am
> > overlooking something
> > small and silly. I was hoping one of the gurus here might have a
> > pointer or suggestion of
> > something I might have missed.
> >
> > Thanks
> >
> > 73, Larry  W6NWS
> > _______________________________________________
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> > Amps at contesting.com
> > http://lists.contesting.com/mailman/listinfo/amps
> >
> 
> 
> 
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