Topband: Fwd: Re: More Inv-L matching issues.... BIGGER ISSUE

[Mike & Coreen Smith]

I replied to Dan directly that I had a very similar antenna and switch here, 
with the box only being a few feet away from the switch and no issues.
I just had another thought.  Is the series capacitor he is using of ample 
size/voltage rating?  Maybe it's arcing @ higher power ?

VE9AA

Mike, Coreen & Corey Smith
699 Rte 616 Keswick Ridge
NB
Canada
E6L 1T1
  ----- Original Message ----- 
  From: Paul Dulaff
  To: Dan Bookwalter
  Cc: topband at contesting.com
  Sent: Sunday, January 01, 2012 2:27 PM
  Subject: Topband: Fwd: Re: More Inv-L matching issues.... BIGGER ISSUE


  Dan

  I understand that your 160 meter station is/was working until you 
introduced the 374A to the system.

  If this is the first time you have manually loaded up the 374A on 160 
meters, it may be possible that the amp is tuned up for output on 80 meters. 
C18 (tune cap) is the only capacitor in the tank circuit, so is possible to 
reduce its capacitance down to tune on 80 meters when the bandswitch is set 
for 160 meters.

  It is possible to input to the amp on 160 meters, having the output tank 
circuit tuned to 80 meters and the amplifier develop an output. The 
amplifier in this case would be acting as a frequency doubler and would 
output high power at 2X the desired frequency. The impedance at the antenna 
would be completely wrong in this situation and would explain the immediate 
failure of the relay box.

  As a check, confirm that C18 (tune variable capacitor) is at full mesh 
(max. capacitance). Tune and load the 374A into a dummy load, slowly 
decreasing C18 until the first dip in plate current is noted.

  Best 73's

  Paul - WB2NMI


  ----- Forwarded Message -----
  From: Paul Dulaff <pdulaff at embarqmail.com>
  To: Dan Bookwalter <N8DCJ at YAHOO.COM>
  Cc: topband at contesting.com
  Sent: Sat, 31 Dec 2011 20:21:44 -0500 (EST)
  Subject: Re: Topband:  More Inv-L matching issues.... BIGGER ISSUE

  Dan

  A couple of thoughts...

  When transmitting, is the RCS-10 antenna switch inadvertantly changing 
(switching) antennas (ports) during the transition from receive to transmit, 
possibly RF getting into the switching circuit causing this ? Do you lose 
the 12VDC to the switch when changing from receive to transmit ?  Are you 
trying to support semi-break-in with the RCS-10 ?

  The ratings on this switch are fairly good. 16 amps, 1200 volts. I would 
think that it would need to be feeding an open or a short to fail this 
quickly at this power level or switching at full power.

  Paul - WB2NMI


  ----- Original Message -----
  From: Dan Bookwalter <n8dcj at yahoo.com>
  To: topband at contesting.com
  Sent: Sat, 31 Dec 2011 17:34:09 -0500 (EST)
  Subject: Topband:  More Inv-L matching issues.... BIGGER ISSUE

  Ok...

  I went and added 9 more radials the SWR is now at 1.2:1 after some 
adjusting of the air variable....

  well , i decided to see how the amp (Alpha 374A) loaded into the antenna , 
I keyed down with maybe 500 watts and everything went dead again in less 
that 1 second. So it now appears that I have smoked another relay in the 
RCS-10 .

  One thing about this configuration is that the base of the antenna is 
about 16" from the RCS-10 , is this too close ? I can probably move it so 
that it is about 4' away if that is the issue.... I cant afford to keep 
destroying relays and such....

  thoughts ?

  Dan N8DCJ


  ________________________________

  -----Original Message-----
  From: topband-bounces at contesting.com 
[mailto:topband-bounces at contesting.com]
  On Behalf Of Dan Bookwalter
  Sent: Saturday, December 31, 2011 2:41 PM
  To: topband at contesting.com
  Subject: Topband: More Inv-L matching issues....

  well about a month ago i put up my Inv-L , it is now ~165ft , I have an 
air
  variable in series , and 12 radials anywhere from 150-250ft long ( going 
out
  to add more as soon as i am done typing this). my SWR wasn't too bad maybe
  1.7:1 at the best. Two nights ago I added an amplifier to the mix ~700w ,
  well to make a long story short I smoked one of the relays in my RCS-10 , 
I
  am now not too sure what to do , I don't want to keep blowing out relays 
in
  the RCS-10.

  I had several responses back then regarding matching etc... , but , in my
  haste i seem to have deleted them :-(

  so here i am again asking for advice...

  any help greatly appreciated

  Dan N8DCJ
  _______________________________________________
  UR RST IS ... ... ..9 QSB QSB - hw? BK
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  UR RST IS ... ... ..9 QSB QSB - hw? BK


  _______________________________________________
  UR RST IS ... ... ..9 QSB QSB - hw? BK


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