Is that not alot of power for ft8. Maybe the software is throttling you back.
Get Outlook for iOS<https://aka.ms/o0ukef> ________________________________ From: elecraft-boun...@mailman.qth.net <elecraft-boun...@mailman.qth.net> on behalf of elecraft-requ...@mailman.qth.net <elecraft-requ...@mailman.qth.net> Sent: Thursday, April 17, 2025 12:00:18 PM To: elecraft@mailman.qth.net <elecraft@mailman.qth.net> Subject: Elecraft Digest, Vol 252, Issue 13 Send Elecraft mailing list submissions to elecraft@mailman.qth.net To subscribe or unsubscribe via the World Wide Web, visit http://mailman.qth.net/mailman/listinfo/elecraft or, via email, send a message with subject or body 'help' to elecraft-requ...@mailman.qth.net You can reach the person managing the list at elecraft-ow...@mailman.qth.net When replying, please edit your Subject line so it is more specific than "Re: Contents of Elecraft digest..." Today's Topics: 1. Intermittent low output KPA500 (phi...@comcast.net) 2. Re: Intermittent low output KPA500 (Jack Brindle) 3. Re: ? Intermittent low output KPA500 (G) 4. K2/100 Fault finding (Steve Bunting) 5. Re: K2/100 Fault finding (Michael Carter) ---------------------------------------------------------------------- Message: 1 Date: Wed, 16 Apr 2025 14:01:11 -0400 From: phi...@comcast.net To: Elecraft@mailman.qth.net Subject: [Elecraft] Intermittent low output KPA500 Message-ID: <8765654b-73fd-4298-ab39-500cf3445...@comcast.net> Content-Type: text/plain; charset=utf-8 In the last few days I have noticed that when operating FT8 using my KAT500/KPA500 combo with an IC-7610, my output seems low on the first or second transmit cycles after switching bands. If I am chasing DX I usually run about 120 to 160 Watts, which is about 6 to 8 Watts on the transmitter. I am seeing only 50 or 60 Watts on the amp when I first transmit. After a couple cycles it goes to the higher output and is stable after that. When changing bands, I switch the radio, with the amp in Standby, then switch bands on the amp before transmitting. Sometimes I use Tune in WSJT-X running just a few watts with the amp in Standby for the amp to automatically switch bands. My antennas have low SWR on most bands, so the tuner is often in Bypass. This seems to have just started and most often occurs on 20 Meters using a GAP 20 Meter Mono-band. I also run CW and some SSB but don?t notice the power meter as much as on FT8. I don?t thing it?s happening there. Has anyone seen this or a similar problem? Phil N3ZP ------------------------------ Message: 2 Date: Wed, 16 Apr 2025 13:41:34 -0500 From: Jack Brindle <jackbrin...@me.com> To: phi...@comcast.net Cc: Elecraft@mailman.qth.net Subject: Re: [Elecraft] Intermittent low output KPA500 Message-ID: <b32a38af-8b99-4322-88b4-c5e4c5ce0...@me.com> Content-Type: text/plain; charset=utf-8 Place a watt meter between the transceiver and the KPA500 and measure the TX output into the KPA. I think you will find the transceiver output is low at those times. This is fairly common in the K3/K3S world when the tx needs to be recalibrated. I would suggest that your 7610 may need recalibration as well. The KPA500 is a linear amplifier - it has fixed gain. The only thing in the KPA500 that could change the gain is a 3db pad in the front end that is invoked when the controller sees something amiss, but not so bad as to declare a fault (yet). You would see a flashing red LED on the KPA when this is invoked. Since you didn?t mention a flashing LED on the KPA, I can only assume the pad is not being invoked. This then points at the driving tx for low output. 73, Jack, W6FB > On Apr 16, 2025, at 1:01?PM, Phil Zminda via Elecraft > <elecraft@mailman.qth.net> wrote: > > In the last few days I have noticed that when operating FT8 using my > KAT500/KPA500 combo with an IC-7610, my output seems low on the first or > second transmit cycles after switching bands. If I am chasing DX I usually > run about 120 to 160 Watts, which is about 6 to 8 Watts on the transmitter. I > am seeing only 50 or 60 Watts on the amp when I first transmit. After a > couple cycles it goes to the higher output and is stable after that. > > When changing bands, I switch the radio, with the amp in Standby, then switch > bands on the amp before transmitting. Sometimes I use Tune in WSJT-X running > just a few watts with the amp in Standby for the amp to automatically switch > bands. My antennas have low SWR on most bands, so the tuner is often in > Bypass. > > This seems to have just started and most often occurs on 20 Meters using a > GAP 20 Meter Mono-band. > > I also run CW and some SSB but don?t notice the power meter as much as on > FT8. I don?t thing it?s happening there. > > Has anyone seen this or a similar problem? > > Phil N3ZP > ______________________________________________________________ > Elecraft mailing list > Home: http://mailman.qth.net/mailman/listinfo/elecraft > Help: http://mailman.qth.net/mmfaq.htm > Post: mailto:Elecraft@mailman.qth.net > > This list hosted by: http://www.qsl.net > Please help support this email list: http://www.qsl.net/donate.html > Message delivered to jackbrin...@me.com ------------------------------ Message: 3 Date: Wed, 16 Apr 2025 19:05:44 +0000 From: G <g...@gmx.net> To: elecraft@mailman.qth.net Subject: Re: [Elecraft] ? Intermittent low output KPA500 Message-ID: <trinity-2945b112-3061-499f-83ab-1614daa961cd-1744830344655@trinity-msg-rest-gmx-gmx-live-6c784bf6f5-mlk6j> Content-Type: text/plain; charset="UTF-8" ------------------------------ Message: 4 Date: Thu, 17 Apr 2025 12:04:37 +0100 (BST) From: Steve Bunting <stephen.bunt...@virgin.net> To: "elecraft@mailman.qth.net" <elecraft@mailman.qth.net> Subject: [Elecraft] K2/100 Fault finding Message-ID: <448014196.3592505.1744887877...@mail.virginmedia.com> Content-Type: text/plain; charset=UTF-8 Hi everyone, I have a K2/100 from an SK sale that works just fine in qrp mode but not above 10W on any band (into a good load). The final transistors get warm with the radio set at 20W and test good afaik. Referring to the test voltages in the manual, I find that D14 does not get 115v on the cathode when transmitting above 10w, which suggests I have a T/R switch problem. Q6 and Q7 have the correct voltages on them, although my (old) semiconductor tester fails to identify them at all. I am not sure I trust that result. R13 tests good, but is very hot when transmitting at for 3 or 3 seconds at the 20W level. I am a bit stuck - Can anyone suggest what I do next? Thanks Steve, M0BPQ ------------------------------ Message: 5 Date: Thu, 17 Apr 2025 12:36:39 +0000 From: Michael Carter <mike.car...@unh.edu> To: Elecraft Reflector Reflector <Elecraft@mailman.qth.net> Subject: Re: [Elecraft] K2/100 Fault finding Message-ID: <bl3p223mb03856357cdb14f0a550fe1b8e4...@bl3p223mb0385.namp223.prod.outlook.com> Content-Type: text/plain; charset="iso-8859-1" Hi Steve, The absence of the high voltage reverse bias supply on the cathodes of D12 and D14 when in TX key-down state suggests two possibilities 1. 1. Q6 has failed with a permanent drain-to-source short. That would provide a path for current through D14 as well as through D13 when in transmit mode for power settings above 10 watts. 2. The high voltage bias supply has failed. This is easily checked by measuring the DC voltage at the junction of R11 (510k) and C77 (0.015 uF). Please let us know what you find. If your old transistor tester is designed to test NMOS FETs, I would be surprised. It's best to just measure the drain voltage of Q6, first in RX mode, then in TX mode. Be sure the transmit power control is set above 10 watts to engage the PA module. In RX mode that Q6 drain voltage should be low, less than 1 V, while in TX mode it should be quite high, at least 90V DC. 73, Mike, K8CN ------------------------------ _______________________________________________ Elecraft mailing list Post to: Elecraft@mailman.qth.net http://mailman.qth.net/mailman/listinfo/elecraft You must be a subscriber to post. Elecraft web page: http://www.elecraft.com End of Elecraft Digest, Vol 252, Issue 13 ***************************************** ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to arch...@mail-archive.com
