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: [email protected] 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 <[email protected]> To: Dan Bookwalter <[email protected]> Cc: [email protected] 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 <[email protected]> To: [email protected] 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: [email protected] [mailto:[email protected]] On Behalf Of Dan Bookwalter Sent: Saturday, December 31, 2011 2:41 PM To: [email protected] 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 ----- No virus found in this message. Checked by AVG - www.avg.com Version: 2012.0.1901 / Virus Database: 2109/4714 - Release Date: 12/31/11 _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK ------------------------------------------------------------------------------ No virus found in this incoming message. Checked by AVG - www.avg.com Version: 8.5.454 / Virus Database: 271.1.1/4115 - Release Date: 12/31/11 19:33:00 _______________________________________________ UR RST IS ... ... ..9 QSB QSB - hw? BK
