[Elecraft] XV mods
I don't know if others have had the issues I've had with the XV transverters, but I thought I'd report on my efforts this weekend .. I run a stack of 4 XVs driving high-power TE amps in my rover. Antennas are short yagis spaced relatively close to each other on one mast. I've experienced failures of the PHEMT due to the large amount of RF present on the unselected transverters, whose configuration leaves the gate of the PHEMT connected to the antenna connector in that state. I suspect bandpass filters would probably eliminate the problem (I have one on the 6M, but space is at a premium ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
[Elecraft] XV mods
sorry about that, accidentally hit send :) I don't know if others have had the issues I've had with the XV transverters, but I thought I'd report on my efforts this weekend .. I run a stack of 4 XVs driving high-power TE amps in my rover. Antennas are short yagis spaced relatively close to each other on one mast. I've experienced failures of the PHEMT due to the large amount of RF present on the unselected transverters, whose configuration leaves the gate of the PHEMT connected to the antenna connector in that state. I suspect bandpass filters would probably eliminate the problem (I have one on the 6M station and it's not given me any problems), but space is at a premium in the rover. I decided to modify the XVs in the following fashion: I remove the jumper from the antenna connector to the pad leading to the common on K1, and attach it to the W3 pad that's connected to the NO contact, then cut the trace between the NO contact and W3 (leaving W3 and the N connector connected to the output circuitry). I short the K1 common to ground. K1's NC contact is conveniently already tied to the input circuitry, and I add W2 for split output. Cut trace to K1 coil and reroute to 12V (powered when XV selected). This repurposes K1 to short the input circuitry to ground whenever K1 is not energized (XV not selected). It's an easy mod for 6/2/222, but a bit of a PITA for 432 (W3 is under K1). I've also modified my TE amps by removing the T/R relay, and am adding external T/R after the amp. de w1rt/john ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
Re: [Elecraft] XV mods
John, Would external coaxial notching filters be practical for you? Another thought (perhaps easier to implement) is an added small relay in each transverter to RF ground the PHEMT's gate (or antenna connection) in the unselected transverters. This would avoid the increase in noise figures caused by the insertion loss of added bandpass filters. I don't have the circuit diagrams to hand to see if the capacity between open relay contacts would upset things when connected to the selected PHEMT's gate or whether it could be tuned out. 73, Geoff GM4ESD - Original Message - From: John D'Ausilio [EMAIL PROTECTED] To: Elecraft Mailing List elecraft@mailman.qth.net; [EMAIL PROTECTED] Sent: Tuesday, March 20, 2007 12:52 PM Subject: [Elecraft] XV mods I run a stack of 4 XVs driving high-power TE amps in my rover. Antennas are short yagis spaced relatively close to each other on one mast. I've experienced failures of the PHEMT due to the large amount of RF present on the unselected transverters, whose configuration leaves the gate of the PHEMT connected to the antenna connector in that state. I suspect bandpass filters would probably eliminate the problem (I have one on the 6M, but space is at a premium ___ Elecraft mailing list Post to: Elecraft@mailman.qth.net You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com
