[Elecraft] KPA500 ISSUE

[Rick Bates, nk7i]

G'morning,

That the amp does occasionally reach 500 out hints that it's not the 
issue; but the rig driving the amp.

You didn't mention the rig, but watch what it is putting into the 
KPA500.  It could be as simple as an output calibration.

I would DEFINITELY verify that the TX audio into the rig, is correct 
(high enough for full output, but not high enough for ANY ALC).

On the K3, that is 4 bars with the 5th flickering, a little.  On the K4, 
that is 8 bars (to the 5), again just flickering.  On another brand, 
bring up the audio until the output power (any level) doesn't climb any 
more, then back it down to where the output JUST starts to fall ('close 
enough' but ask another station to watch your signal for purity).

Windows updates tend to muck with your settings, verify after each major 
update that they're what you wanted.  Take notes.

Also check that your coax is valid (not failing) with connectors snug.

73,
Rick nk7i


On 7/2/2024 7:39 AM, Terry Myers wrote:
> I think I have seen this discussed before, but I have not found it in the archives.  So point me in the right direction or if you have the cause and cure please pass it along.
> The KPA500 Ser. No. between 1K & 2K or about 10 years old.  It has been in daily use without a problem until this faithful day.
> I have not been able to do a full check yet because I changed computers sometime back and I no longer have a RS232 on the computer, so I ordered the necessary part from Elecraft.
>
> What I am seeing ( using FT8) is no output on 6M, on the HF bands the power increases in steps 50W then 60W then 70W and on the next cycle it will start at 60W then 80W, 90W, etc.  In a few cycles it might get up to 500W, but it varies as to which HF band I'm on.
> I'm thinking is it's microprocessor brain got scrambled with the RF.  I can't check until I get the cable, its on order.  If you had this problem, was more than a memory flash needed.  Maybe a few parts replaced, etc?  Did you discover any preventive measures?
> If so, let me hear from you.
> 73,Terry, KQ5U
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