Over the past two weeks I’ve had faults occur at seemingly random times that read “50V SUPPLY IDLE CURRENT EXCEED” – flashing and beeping, and preventing the 8000 from starting. Read on in case this happens to you. I hope I can save you some worry.

I was noticing two strange things: 1) The two-tone test (triggered from the Linearity menu) was causing a distinct buzzing noise that increased in volume with increasing transmit power (drive) level, and 2) it sometimes caused one of these faults to occur as I reached a level up around 100W or so. Otherwise operation of the rig was completely normal, on CW, on SSB, on AM, at all power levels, with or without driving an amplifier. Only during two-tone test was this occurring, or soon afterward on restarting.

When this fault happens, the only way to recover seems to be to shut down the main power, shut down the power supply too, wait 10-15 minutes (maybe longer), and restart the unit. The first time it happened it took only a minute or less to recover, so when it didn’t recover this afternoon I sent an email to Apache support around 3:00 p.m. reporting the problem and fearing the worst.

I was pleased to receive an email response from Apache at 6:23 p.m. – what I judged to be very fast! The support person reported that there was a bug in the LCD code that might be causing this, and sent along version 1.07 for me to try. I did, and it went immediately back to starting up in fault mode after the load. Uh-oh. I then pushed in the “STANDBY” button and restarted (i.e. re-connected the USB cable) and this time everything went back to normal. I don’t know if starting in STBY did anything or if just restarting a second time did.

One more thing. I suspect that the two-tone test is stressing my power supply, a Jetstream JTPS45 switching PS. The buzzing noise I mentioned above, which I thought was coming from the 8000, was actually coming from the PS. I hooked up a scope to the terminals and noticed that there was a pronounced modulation of the output occurring, that resembled the two-tone test signal. It’s not RF-caused because a bypass capacitor didn’t make any difference whatsoever. This PS just seems to not like having an AF varying load. I surmise that when this modulated supply voltage gets up to a certain level in amplitude (i.e. as I increase the drive level), the logic in the LCD board and processor, who get their power from this source, throw up their hands in frustration and have a seizure.

By the way, modulation of other kinds – voice, cw, etc. – also cause fluctuations in the PS output, resembling the modulation characteristic. So I’m guessing further that the tones present in the 2TT are especially annoying to the JTPS45’s circuitry.

I don’t know if this is something characteristic of this model of PS, the JTPS45, or whether it’s a problem with my particular unit. I plan to contact Jetstream, and try another PS, too.

The scary part of all this was that along with a warning of excessive current and a buzzing noise, which was quite similar to an arcing sound with a frequency similar to the 2TT, and the power supply itself going into its own fault mode along with the 8000, it was beginning to feel like something was seriously wrong with the hardware. I began to envision charred components.  But once I realized the sound was coming from the PS and then was able to recreate the fault with only the 8000’s LCD board powered (via USB while updating the firmware), it became clear this had nothing to do with the actual 50V supply in the 8000.

All is well now. No more faults thus far. I plan to avoid using the 2-tone-test entirely until I get a different power supply or figure out if this one can be cured.

(Also posted to the Apache forum with some follow-up.)

de W2PA