From edwa9gqk at yahoo.com  Fri Jul 15 12:39:13 2011
From: edwa9gqk at yahoo.com (EDWARD SCHUMACHER)
Date: Fri, 15 Jul 2011 09:39:13 -0700 (PDT)
Subject: [SignalOne] Progress
Message-ID: <1310747953.64076.YahooMailNeo@web45216.mail.sp1.yahoo.com>

It has been a torturous process but I am finally making some positive progress in bringing SN 00847 back to life. As with the first effort after acquiring the radio, it has been a intense learning experience. Turns out the receiver was not quite dead so it will be possible to troubleshoot. Front end and audio are good so problem may be back at the nefarious Schmidt trigger T/R switch circuit. Finally have the last problems fixed on the display and will also have to figure out the low power out (maybe also related to the T/R switch if that is what is 

going on). Also seems some of the fuse blowing may have been caused by the NOS final. Suspect it may be shorting after warming up awhile so have reinstalled the old tube again.

At this time I would like to know if anyone has had occasion to replace the driver transistors and where to obtain replacements. I have not started checking suppliers yet and do have all the old info from the newsletters. My rig has the TRW at Q3 but the Q4 device is marked K 1013 and does seem to have low output according to my old notes. I have had good luck with the folks at RF Parts, especially for the better Mot dual gate MOSFETs for the front end.

I hope to have the receive completely back shortly and possibly with it the xmit. With the radio on the bench this long, I feel I should go after the Driver board now too so am planning the extra work.


Ed, WA9GQK

From edwa9gqk at yahoo.com  Sat Jul 16 12:43:49 2011
From: edwa9gqk at yahoo.com (EDWARD SCHUMACHER)
Date: Sat, 16 Jul 2011 09:43:49 -0700 (PDT)
Subject: [SignalOne] Replies
Message-ID: <1310834629.63920.YahooMailNeo@web45205.mail.sp1.yahoo.com>

Thanks to all for the replies on my posting. Am spending the next couple of days studying the driver board and checking power supply and t/r voltages to get the receiver back up and verify what all may have been done on the driver board. Yes, I have read all the info about installing the drivers and will finally chase down the rest of the info on recommended mods. Some have already been done on this radio. Am also pretty busy preparing for another of my activities that takes place in another couple of weeks so have a very full schedule right now.

By the buy, was anyone else at Dayton and saw the CX-11 for sale? I think it was $650 for a radio with an agc and one other known problem and not very clean condx either (garage kept?). Thanks again and ...

73 - Ed, WA9GQK

From N4ch at aol.com  Sun Jul 17 19:16:25 2011
From: N4ch at aol.com (N4ch at aol.com)
Date: Sun, 17 Jul 2011 19:16:25 -0400 (EDT)
Subject: [SignalOne] Replies
Message-ID: <33869.dcf11e8.3b54c749@aol.com>

Hello Ed (and others).......
 
Sorry for the late response (I was out of town for a couple  days......no 
email), but I DID see the subject CX-11 at Dayton, right after the  guy put 
it on the block.   Yes, he indicated it had several major  problems (and one 
of them was with the AGC), and I think one of the other issues  may have 
been power supply-related.   I considered buying it until I  heard what he 
wanted, and what all would be involved (he THOUGHT), getting it  airworthy.   
Yes, $650 was the initial asking price.   I saw  it pretty early Friday, and 
when I walked by a short time later it was  gone.   I know the new 
owner.......Randy, W9ZR showed it to me in his  vehicle the next morning, and I am 
assuming he still has it but I've not talked  to him since Dayton.   I'd love 
to have one of these rare rigs, but at  this point I'm trying to cut back on 
buying as much big, heavy, and difficult to  restore stuff as I used to go 
after.
 
73 all......Herman, N4CH.
 

From edwa9gqk at yahoo.com  Mon Jul 18 19:36:48 2011
From: edwa9gqk at yahoo.com (EDWARD SCHUMACHER)
Date: Mon, 18 Jul 2011 16:36:48 -0700 (PDT)
Subject: [SignalOne] CX-11
Message-ID: <1311032208.25634.YahooMailNeo@web45202.mail.sp1.yahoo.com>

Glad to see the rig has found a good home. Felt sort of bad having to walk away but with my own rig still in trouble and the substantial asking price I had no choice. I will probably be spending some time on my rig this week just because it is too blamed hot outside to do anything else and the basement feels very comfortable right about now, HI!

73 ... Ed

From edwa9gqk at yahoo.com  Sat Jul 23 16:01:46 2011
From: edwa9gqk at yahoo.com (EDWARD SCHUMACHER)
Date: Sat, 23 Jul 2011 13:01:46 -0700 (PDT)
Subject: [SignalOne] Surgistor replacement
Message-ID: <1311451306.18551.YahooMailNeo@web45201.mail.sp1.yahoo.com>

With all my postings re getting my CX-7 fixed, I have not yet posted what I used to replace the surgistor which failed early on in the process. After reviewing all the replies (thanks again to all who gave suggestions) I decided to try one of the NTC thermistors available from Mouser. The 10 ohm @ 7.5 amp and the 2.5 ohm @ 11 amps looked good due to values similar to resistances used in traditional step start relay schemes and current capacity. I ordered one of each and installed the 10 ohm unit. So far, so good. Have not put a scope on the line but what with the MOV's already in the radio and this device my dvm on the 300vdc line shows no surge, just a steady 300vdc. The device does not seem to be throwing much heat either but with the trouble I have had, the rig has not been on for very long at a time yet, HI! Anyway, these devices seem to be a good replacement. Don't know if anyone else can contribute additional experiences with them.

Ed, WA9GQK

From k5am at zianet.com  Sat Jul 23 20:58:42 2011
From: k5am at zianet.com (Mark K5AM)
Date: Sun, 24 Jul 2011 00:58:42 +0000
Subject: [SignalOne] Surgistor replacement
In-Reply-To: <1311451306.18551.YahooMailNeo@web45201.mail.sp1.yahoo.com>
References: <1311451306.18551.YahooMailNeo@web45201.mail.sp1.yahoo.com>
Message-ID: <20110724005904.105883738302@mailman.qth.net>

At 2011-07-23 20:01, Ed, WA9GQK wrote:
>   . . . decided to try one of the NTC thermistors available from 
> Mouser. . . .



I have had good luck with the surgistor specified on page 1 of the
check-out form; pdf for download at   www.zianet.com/k5am/cx7.html

73,

Mark, K5AM
www.zianet.com/k5am




