[Lowfer] 630m overnight
Brian, WA1ZMS
wa1zms at att.net
Thu Dec 28 11:14:01 EST 2017
Mike-
FWIW....
A diplexer on the input port of the mixer may not help much if the output match, S22 of the LNA looks like a reasonable load at 3MHz too. If you have extra LNA gain to lose, a 3dB pad between the LNA and the mixer may be as good as a diplexer.
Mixer's impedance load at all ports is often overlooked until, as you do, want best dynamic range. Maas' book on mixers is a great reference text as well for those who don't have a copy.
-Brian, WA1ZMS
iPhone
> On Dec 28, 2017, at 10:36 AM, Michael Sapp <wa3tts at verizon.net> wrote:
>
> John (& the Lowfer Group): Interesting observation overnight, I was able to decode K9FD with another station reporting being on the same frequency at the same time---although with some drift...
>
> This event occurred once over 10 K9FD decodes. The other evening I saw the same thing happen with the same stations when watching the waterfall in real time. At the time I thought it was a
>
> fluke, but it has happened again last night, so I thought it may be noteworthy.
>
> 10 spots:
> Timestamp Call MHz SNR Drift Grid Pwr Reporter RGrid km az
> 2017-12-28 07:30 K9FD 0.475615 -20 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 07:24 K9FD 0.475615 -22 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 06:50 K9FD 0.475615 -24 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 07:42 K9FD 0.475615 -24 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 07:20 K9FD 0.475615 -27 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 08:16 K9FD 0.475615 -28 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 08:38 K9FD 0.475615 -28 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 06:54 K9FD 0.475615 -29 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 08:20 K9FD 0.475615 -29 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 07:06 K9FD 0.475615 -30 0 BL11je 1 WA3TTS EN90xn 7439 54
>
>
> 2017-12-28 07:20 KC4SIT 0.475615 -2 -1 EM85tg 5 WA3TTS EN90xn 623 18
> 2017-12-28 07:20 K9FD 0.475615 -27 0 BL11je 1 WA3TTS EN90xn 7439 54
>
>
> Given the current WSPR2 situation on 630m, I decided to turn lemons into lemonade and focus on some high dynamic range tinkering over the past few weeks.
>
> For several months my LO driver amp was out of service and I simply bypassed it and made do with the +15 dBm coming out of the
> 3.0 MHz IsoTemp OCXO. When I decided to test RF, LO, and IF diplexer filters on all mixer ports in an attempt to improve IMD and dynamic range,
> I decided it was time to repair the LO driver. In the above decodes, the LO drive was at +23 dBm to the Mini-Circuits RAY6 Level 23 double balanced mixer.
> All 3.0 MHz LO harmonics are at least 60dB down through the LO diplexer as observed on my HP141T spectrum analyzer.
>
> So apparently I have enough dynamic range in my receiver converter to handle 2 WSPR stations that are nearly right on top of each other.
>
> The diplexer filters are simple series and shunt LC combinations with 50 ohm terminations at 3.0 MHz (LO Port), and 3.3 MHz (Mid IF range for LF/MF band).
>
> I had a 475 kHz IF diplexer on the mixer RF port, but it seems to make more of a dynamic range improvement in front of my single-ended 2N5109 preamp. So the next step is to build another
> 475 kHz diplexer for RF mixer port testing.
>
> An explanation of how the diplexers work is here... https://www.youtube.com/watch?v=AMPbG8MfoNI
>
> John (& the Lowfer Group): Interesting observation overnight, I was able to decode K9FD with another station reporting being on the same frequency at the same time---although with some drift...
>
> This event occurred once over 10 K9FD decodes. The other evening I saw the same thing happen with the same stations when watching the waterfall in real time. At the time I thought it was a
>
> fluke, but it has happened again last night, so I thought it may be noteworthy.
>
> 10 spots:
> Timestamp Call MHz SNR Drift Grid Pwr Reporter RGrid km az
> 2017-12-28 07:30 K9FD 0.475615 -20 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 07:24 K9FD 0.475615 -22 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 06:50 K9FD 0.475615 -24 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 07:42 K9FD 0.475615 -24 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 07:20 K9FD 0.475615 -27 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 08:16 K9FD 0.475615 -28 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 08:38 K9FD 0.475615 -28 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 06:54 K9FD 0.475615 -29 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 08:20 K9FD 0.475615 -29 0 BL11je 1 WA3TTS EN90xn 7439 54
> 2017-12-28 07:06 K9FD 0.475615 -30 0 BL11je 1 WA3TTS EN90xn 7439 54
>
>
> 2017-12-28 07:20 KC4SIT 0.475615 -2 -1 EM85tg 5 WA3TTS EN90xn 623 18
> 2017-12-28 07:20 K9FD 0.475615 -27 0 BL11je 1 WA3TTS EN90xn 7439 54
>
>
> Given the current WSPR2 situation on 630m, I decided to turn lemons into lemonade and focus on some high dynamic range tinkering over the past few weeks.
>
> For several months my LO driver amp was out of service and I simply bypassed it and made do with the +15 dBm coming out of the
> 3.0 MHz IsoTemp OCXO. When I decided to test RF, LO, and IF diplexer filters on all mixer ports in an attempt to improve IMD and dynamic range,
> I decided it was time to repair the LO driver. In the above decodes, the LO drive was at +23 dBm to the Mini-Circuits RAY6 Level 23 double balanced mixer.
> All 3.0 MHz LO harmonics are at least 60dB down through the LO diplexer as observed on my HP141T spectrum analyzer.
>
> So apparently I have enough dynamic range in my receiver converter to handle 2 WSPR stations that are nearly right on top of each other.
>
> The diplexer filters are simple series and shunt LC combinations with 50 ohm terminations at 3.0 MHz (LO Port), and 3.3 MHz (Mid IF range for LF/MF band).
>
> I had a 475 kHz IF diplexer on the mixer RF port, but it seems to make more of a dynamic range improvement in front of my single-ended 2N5109 preamp. So the next step is to build another
> 475 kHz diplexer for RF mixer port testing.
>
> An explanation of how the diplexers work is here... https://www.youtube.com/watch?v=AMPbG8MfoNI
>
>
> Data Sheet on the RAY 6 Mixer is here... https://www.dropbox.com/s/8rvksgql313j7kj/RAY6.JPG?dl=0
>
> The RAY6 is a non catalog model that I picked up an Nebraska Surplus Sales a few years ago. A similar Level 23 production-available mixer would be the RAY3 for
>
> those who want to experiment with high dynamic range mixers...
>
>
> 73 Mike wa3tts
>
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