Fake It keeps the tones between 1500-2000 Hz. (not 1000) so that the
harmonic energy is out of the passband.
Also the response of the sound card has some variation at different
pitches (it's not a totally flat response), so try different tones.
73,
Rick NK7I
On 10/21/2020 6:19 AM, Dave wrote:
Conrad,
My friend just had the issue you described with a different brand radio. He was
transmitting near the high end of the TX filter and on higher tones of the FT8
the power would drop causing the TX power to waiver.
The fix for him was to enable Fake It in the WSJT-X radio settings tab. That
keeps the TX audio centered between 1 kHz and 2 kHz. Well within the TX filter
bandwidth.
Dave wo2x
Sent from my waxed string and tin cans.
On Oct 21, 2020, at 7:51 AM, Conrad PA5Y <g0...@g0ruz.com> wrote:
Hello while I wait for feedback from the (no doubt overwhelmed) Elecraft
support I thought that I would ask the group about a problem that I have with
my K3S.
When I run JT65B and even to a lesser extent FT8 I see unacceptable amplitude
variation on both the 6m output and the transverter output (on 28MHz). If I put
my E4406 Spectrum analyser on peak hold with a narrow span and 10Hz RBW I see
amplitude variations of a little over 1dB on the modulation tones across the
passband.
To save time.
1. On the ALC meter I have 4 bars lit up with the 5th occasionally
flickering - the audio drive level is correct; it is not an ALC issue
2. I calibrated the TX drive - the effect is observed at 1mw, 5W, 50W and
100W on 6m.
3. I am using DATA A so no TX EQ or compression
4. The audio has from WSJT-X been measured on a UPV audio analyser and there
is less than 0.1dB variation when using a UMC404HD sound card
5. The effect is observed with both Line input drive and the UMC404HD
soundcard and the internal K3S codec
6. My old TS2000X does not exhibit more than 0.1dB amplitude variation with
the same sound card providing audio and the same test setup
7. I have verified the amplitude variations at RF with a diode detector and
an oscilloscope
8. The effect is clearly visible on several power meters
9. This AM causes some spectral re-growth, although this is tolerable
So given all that I am beginning to wonder if the problem is due to filter
ripple in the standard K3S 2.7kHz filter? I cannot think of anything else. I
was considering buying an Inrad #718 filter.
This is very critical for EME when signals are weak at the RX side, if you have
amplitude variations and you are at the threshold of detection at the receiving
station this can cause decodes to fail. This is more important on 6m EME than
2m where I have more margin.
I think that this will be quite common, has anybody else got a K3S and the
equipment to check and verify my observations?
73
Conrad PA5Y
______________________________________________________________
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 rocke...@gmail.com
______________________________________________________________
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 rick.n...@gmail.com
______________________________________________________________
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
