My LA-1K is connected to an HF-AUTO tuner and an ICOM 7610. I have the data cable connected from the 7610 to the amplifier. When the amplifier is in "Direct Mode" (using the data cable for PTT and band switching) and transmitting CW (Semi BKIN) it will go into "Overdrive" and stop after maybe 15 seconds. This doesn't happen with SSB. It doesn't matter how low the power I drive the amp with is. It resets quickly and will then do the same thing again after a few seconds of transmitting. When the amp is in "Normal Mode" even with the data cable still connected this does not happen at all. This behavior occurs as above with or without the RCA PTT connection being used.
I have been going back and forth with Mark at Palstar and so far he hasn't figured this one out. I'm wondering if it might be some strange thing going on with my setup or if anyone else here has experienced this. For now my solution is to just use CW in Normal Mode and SSB in Direct Mode. -- 73, Jerry
?? I'm sure Mark has mentioned this to you, but are you sure the exciter isn't spiking it's drive power?? The ALC circuits in many radios have enough delay in them that they'll spike on leading edges often WITHOUT regard to the selected power output.? It depends on how the radio limits it's power internally.? I use an external negative ALC voltage applied to my radio's ALC jack using a 9v battery and a 20-turn pot.? That way it doesn't wait for the radio's internal ALC to respond and limit output... it's there all of the time.? Some radios limit the power at an early stage so they don't spike.? I'm not familiar with the 7610.? You'll never see this on any meter, but it is visible on a scope sampling the output.? The LA-1K responds very rapidly to overdrive so the occasional leading-edge surge will activate overdrive protection.
On 4/4/2019 at 10:49 AM, "JERRY" <JERRY@...> wrote:
[Edited Message Follows]
My LA-1K is connected to an HF-AUTO tuner and an ICOM 7610. I have the data cable connected from the 7610 to the amplifier. When the amplifier is in "Direct Mode" (using the data cable for PTT and band switching) and transmitting CW (Semi BKIN) it will go into "Overdrive" and stop after maybe 15 seconds. This doesn't happen with SSB. It doesn't matter how low the power I drive the amp with is. It resets quickly and will then do the same thing again after a few seconds of transmitting. When the amp is in "Normal Mode" even with the data cable still connected this does not happen at all. This behavior occurs as above with or without the RCA PTT connection being used.
I have been going back and forth with Mark at Palstar and so far he hasn't figured this one out. I'm wondering if it might be some strange thing going on with my setup or if anyone else here has experienced this. For now my solution is to just use CW in Normal Mode and SSB in Direct Mode. -- 73, Jerry
Hi Dennis, No Mark didn't mention it but it is interesting especially because the amp doesn't use ALC for CW so this spike you mention from the radio makes sense. This could also explain why it only happens in Direct mode.? -- 73, Jerry
Jerry Raia