PR-6 issue when QRO
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Gregg, I can only comment that I have exactly the same setup on 6 with PR 6 and a W1QJ sb-220, and have never had any issue. The PR6 is connected to K3 acc output for programmed band dependant switching etc as per manual; " The PR6 can be connected directly to the RX ANT IN/OUT jacks on the K3's KXV3 module (required), where it can be switched in automatically by the transceiver when operating on 6 meters. A second pair of jacks is provided on the opposite side of the PR6 to allow use of the K3's normal RX ANT IN/OUT signal path when the preamp is not in use. Power for the PR6 can be obtained from any 11 to 14 VDC supply. When used with a K3, the PR6 can be powered from the 12 VDC accessory output. It can be strapped permanently ON, or it can be turned on/off externally from an open-source/open-drain logic signal. In the K3 case, the DIGOUT1 control line can be used (on the 15-pin ACC jack), since it is stored on a per-band basis." The antenna is a InnovAntenna 7EL LFA yagi and there is no feedline radiation. There is a coax choke wound near the loop termination.. As the PR6 circuit is only utilised during RX , I can only think you have a feedline radiation issue or similar. My PR-6 12v line connects to a large electrolytic capacitor where a stiff 15v supply cable for the K3 passes through to the K3 APP connectors. So the input is well protected by spikes etc. That may be worth considering re: capacitor? Adrian ... vk4tux -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of Gregg Marco W6IZT Sent: Sunday, 29 April 2012 10:55 PM To: 'elecraft' Subject: [Elecraft] PR-6 issue when QRO I use my K3 on 6 meters with a concerted SB-220. When using the PR6 connected to the KXV3 as intended and using the amp, the GaAs FET is destroyed immediately. My work around was to employ an external TR relay on the K3 to switch TX RX, connecting the PR6 to the RX side of the relay and to the RX input of the KXV3.Using this arrangement has worked fine for the past few years. With E skip season approaching I thought that I would try to resolve this problem and get rid of the extra RF plumbing. My initial thought was the TR relay in the amp might be too slow and RF was being reflected back into the K3 during the transition from TX to RX. After looking at the K3 block diagram I doubt that this is the case as the PR-6 should be switched out of the circuit well before any RF is present at the output. For reference the TR relays in the amp are spec'ed at 8 msec to switch and the K3 is set at 8 msec TX delay, which I believe is the default. Any ideas? 73 Gregg W6IZT ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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Gregg, check inside the amp and see if the RF choke between the pi network and the antenna jack is OK.
I was running a SB221 converted to 6 and i had a bad choke connection to ground and when going to receive it would blow the rec. pre amp. what happens when that choke fails the plate blocking cap builds up a neg charge on the pi side and has no way to discharge untill it goes to receive and it discharges through the pre amp. the choke will discharge everything from the pi network to the antenna, FWIW Ed K7WIA |
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Ed, > what happens when that choke fails the plate blocking cap builds up > a neg charge on the pi side and has no way to discharge untill it > goes to receive and it discharges through the pre amp. But with the PR6 one would expect that negative voltage to impact the KAT3, the lowpass filters, the PIN diode T/R switch in the KPA3, and the PIN diode T/R switch on the mainboard *before* it got to the pre-amp. There are DC paths to ground, blocking caps and several sensitive components between the antenna jack and the PR-6 that I would expect to be take the brunt of a discharge before the PR-6 was damaged. 73, ... Joe, W4TV On 4/29/2012 8:55 PM, K7WIA wrote: > Gregg, check inside the amp and see if the RF choke between the pi network > and the antenna jack is OK. > > I was running a SB221 converted to 6 and i had a bad choke connection to > ground and when going to receive it would blow the rec. pre amp. > > what happens when that choke fails the plate blocking cap builds up a neg > charge on the pi side and has no way to discharge untill it goes to receive > and it discharges through the pre amp. > the choke will discharge everything from the pi network to the antenna, > > FWIW Ed K7WIA > > -- > View this message in context: http://elecraft.365791.n2.nabble.com/PR-6-issue-when-QRO-tp7511705p7512096.html > Sent from the Elecraft mailing list archive at Nabble.com. > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:[hidden email] > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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In reply to this post by vk4tux
If it is slow relay switching, this could be added to the switching ckt.
http://www.w6pql.com/relay_sequencer.htm Ed K7WIA |
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Perhaps so if the relays were fast enough already, using the AG6K sb-220
design speedup key circuit (EBS) with Jennings RJ1A or Kilovac HC1 relays, with the 12v reed input relay works nice at 2mS switch times, good for 35 wpm qsk. I have this setup in one of mine and its very economical to setup.; http://www.somis.org/QSK922.html http://www.somis.org/D-a-07B.jpg Adrian ... vk4tux -----Original Message----- From: [hidden email] [mailto:[hidden email]] On Behalf Of K7WIA Sent: Tuesday, 1 May 2012 1:30 AM To: [hidden email] Subject: Re: [Elecraft] PR-6 issue when QRO If it is slow relay switching, this could be added to the switching ckt. http://www.w6pql.com/relay_sequencer.htm Ed K7WIA ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[hidden email] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html |
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