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

To: "Amps" <amps@contesting.com>
Subject: Re: [Amps] Suggestions - I broke my amp - part 2
From: "Larry" <lknain@nc.rr.com>
Reply-to: Larry <w6nws@arrl.net>
Date: Wed, 17 Nov 2010 20:17:23 -0500
List-post: <amps@contesting.com">mailto:amps@contesting.com>
Not that I know of. The amp was working except it needed new parasitic 
suppressors. I 
replaced the suppressors, the plate RFC, and the plate blocking cap. The output 
network
itself was not touched except that I changed a pair of doorknobs (200pf each) 
with a 500pf
doorknob that gets switched in parallel with the tuning cap for 160. I also 
added an additional
200pf doorknob that gets switched in parallel with the loading cap for 160. 
They look correct
with an ohmmeter. 

I am going over things yet again and reheating solder connections just in case 
I missed something.

73, Larry  W6NWS
  ----- Original Message ----- 
  From: Dave M 
  To: w6nws@arrl.net ; amps@contesting.com 
  Sent: Wednesday, November 17, 2010 7:15 PM
  Subject: RE: [Amps] Suggestions - I broke my amp - part 2


  Possible arc over and short of the tune cap ??


  
......................................................................................................

  73     VE3DV , Dave




    

  > From: lknain@nc.rr.com
  > To: amps@contesting.com
  > Date: Wed, 17 Nov 2010 18:42:29 -0500
  > Subject: Re: [Amps] Suggestions - I broke my amp - part 2
  > 
  > It turns out it doesn't matter about the bandswitch position - same result 
  > in all positions regardless
  > of the transmitter freq. The bandswitch seems OK by visual inspection and 
  > with an ohmmeter.
  > I have to wonder where the power is going. No arcing, no noticeable heating 
  > so far but I
  > don't run it too long since it is obviously not working correctly.
  > 
  > 73, Larry W6NWS
  > ----- Original Message ----- 
  > From: "Gary Schafer" <garyschafer@comcast.net>
  > To: <n8de@thepoint.net>; "'Larry'" <w6nws@arrl.net>; "'Larry'" 
  > <lknain@nc.rr.com>
  > Cc: "'Amps'" <amps@contesting.com>
  > Sent: Tuesday, November 16, 2010 10:17 PM
  > Subject: RE: [Amps] Suggestions - I broke my amp - part 2
  > 
  > 
  > > 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@contesting.com [mailto:amps-bounces@contesting.com] On
  > >> Behalf Of n8de@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@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
  > >> > _______________________________________________
  > >> > Amps mailing list
  > >> > Amps@contesting.com
  > >> > http://lists.contesting.com/mailman/listinfo/amps
  > >> >
  > >>
  > >>
  > >>
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  > >> http://lists.contesting.com/mailman/listinfo/amps
  > >
  > > 
  > 
  > 
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