[Elecraft] When Transmitting on FT8 - KPA500 has issues - KD8ZYD

[Walter Underwood]

Does it happen at 200 W? Sometimes RF in the shack shows up only at higher power levels.

wunder
K6WRU
Walter Underwood
CM87wj
http://observer.wunderwood.org/ (my blog)

> On Jul 1, 2019, at 9:39 PM, Mark Goldberg <marklgoldberg at gmail.com> wrote:
> 
> I'm going to take these two postings and suggest the possibility of RF
> getting into the USB link to the PC causing it to drop samples.
> 
> Check the grounds and make sure there is a good ground connection between
> the PC, Signalink and the radio equipment. Try ferrite beads (Mix 31) on
> the USB line or a different USB cable.
> 
> 73,
> 
> Mark
> W7MLG
> 
> 
> On Mon, Jul 1, 2019 at 9:06 PM Bob McGraw K4TAX <rmcgraw at blomand.net> wrote:
> 
>> A clue..... at 500 watts with the KPA500 there is an issue.  At 50 watts
>> using just the K3 there is no reported issue.  What's the difference?
>> RF field strength.  Sounds like it might be and RFI issue.
>> 
>> Check all PL-259's and make sure they are VERY TIGHT.   Check jumper
>> cables, between each piece of equipment and make sure they are in good
>> condition and connectors are properly attached and installed.   If in
>> doubt, replace them.
>> 
>> 73
>> 
>> Bob, K4TAX
>> 
> 
> 
> 
> On Mon, Jul 1, 2019 at 8:41 PM Michael Walker <va3mw at portcredit.net> wrote:
> 
>> Good to send the video
>> 
>> It sounds like the Sound card is dropping audio frames then and can he test
>> with WSJTx in their TUNE mode.  Does the same thing happen.
>> 
>> If it was me, I would review the sound card settings for the sound card
>> device.  Make sure it IS the one you think it is.
>> 
>> Could the computer be suffering from high DPCs.. aka, is it busy doing
>> something else like a virus scan or indexing?
>> 
>> This is one of those times that it would be good to know more about the
>> computer hardware, like CPU speed, memory, etc.
>> 
>> Mike va3mw
>> 
>> 
>> On Mon, Jul 1, 2019 at 11:15 PM Jack Brindle via Elecraft <
>> elecraft at mailman.qth.net> wrote:
>> 
>>> Fred sent me the video, which is actually very revealing. First the
>> change
>>> rate is very rapid, higher than I initially expected. The asterisk is on
>>> constantly, and the power off time is not long enough for power to drop
>> to
>>> zero. But what I found very interesting is that the output power
>> indication
>>> on the K3 is fluctuating at the same rate as the KPA500 is indicating.
>> That
>>> leads me to believe that the K3 output is rapidly changing on and off.
>> The
>>> next question is what might be causing this - it might be the K3, but it
>>> also could be upstream, in Fred’s Signalink or perhaps the computer /
>>> program that is feeding audio to the radio system.
>>> 
>>> With that in mind, and knowing the calibre of folks on the list who are
>>> very adept at digital setups, let's see if we can troubleshoot the system
>>> and get Fred going again the way things should be.
>>> 
>>> 73!
>>> Jack, W6FB
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