[Lowfer] MF ummer Solstice DX

Michael Sapp wa3tts at verizon.net
Sat Jun 21 17:46:15 EDT 2014 

John: I think it is front end saturation on my end from the LO and AM BCs. 
XJM seems to decode you fine. I'm just on the ragged edge. Will find out 
tonite as my IF preselector is nearly done.......73,

Mike, tts
----- Original Message ----- 
From: "John Langridge" <jlangridge at sbcglobal.net>
To: "Discussion of the Lowfer (US, European, & UK) and MedFer bands" 
<lowfer at mailman.qth.net>
Sent: Saturday, June 21, 2014 3:28 PM
Subject: Re: [Lowfer] MF ummer Solstice DX


Mike,

thanks for the reports, as always. In some of the cases where you see my 
traces but don't get decodes, I suspect that the IF rig is going into fault 
mode due to high temperatures. The shack is located on the west side of the 
house and it can get warm in here during the summer. Even with the AC and 
fans, both internal and external to the rig, the air temp in this room is 
sometimes suspect in and around the electronics. When I am aware of it, I 
simply power the rig down for a few minutes so it can catch up and then 
restart. I am certain that overnight periodic drop outs may occur, leaving 
holes in the 2 minute TX cycles rendering the signal undecodable. I 
appreciate knowing now that at least my traces are being seen. Seems when 
the shack gets above 80F (which is common this time of year), I see this 
behavior. Its never a problem in the winter. I am considering additional 
ventilation so I don't freeze out the rest of the house trying to keep
 the shack cool.

73 and thanks again!

John XIQ





________________________________
 From: Michael Sapp <wa3tts at verizon.net>
To: lowfer at mailman.qth.net
Sent: Saturday, June 21, 2014 9:12 AM
Subject: [Lowfer] MF ummer Solstice DX


Hi All: I was surprised to see XSH/20 in the 630M WSPR2 capture log last 
nite


  2014-06-21 09:12   WD2XSH/20   0.475692   -27   0   CN83lu   +43   19.953 
WA3TTS   EN90xn   3520   2187
  2014-06-21 07:58   WD2XSH/20   0.475692   -28   0   CN83lu   +43   19.953 
WA3TTS   EN90xn   3520   2187
  2014-05-17 09:20   WD2XSH/20   0.475690   -27   0   CN83lu   +37   5.012 
WA3TTS   EN90xn   3520   2187


My EWE was terminated to favor a SW direction, with the antenna pattern 4 or 
so dB down along the response curve to the WNW direction that would favor 
XSH/20. I noticed XJM

had six XSH/20 captures last nite with his RX array, which was an 
encouraging comparison for my small lot situation.


Only several XIQ captures last night, but John's 630M WSPR2 signal was 
providing frequent light traces on the WSPRX waterfall that were not decoded 
overnight.

  2014-06-21 09:04   WG2XIQ   0.475619   -28   0   EM12mp   +30   1.000 
WA3TTS   EN90xn   1743   1083
  2014-06-21 09:00   WG2XIQ   0.475619   -29   0   EM12mp   +30   1.000 
WA3TTS   EN90xn   1743   1083
  2014-06-21 08:48   WG2XIQ   0.475619   -28   0   EM12mp   +30   1.000 
WA3TTS   EN90xn   1743   1083
  2014-06-21 08:40   WG2XIQ   0.475620   -31   0   EM12mp   +30   1.000 
WA3TTS   EN90xn   1743   1083
  2014-06-21 08:16   WG2XIQ   0.475620   -31   0   EM12mp   +30   1.000 
WA3TTS   EN90xn   1743   1083
  2014-06-21 07:36   WG2XIQ   0.475620   -29   0   EM12mp   +30   1.000 
WA3TTS   EN90xn   1743   1083
  2014-06-21 03:36   WG2XIQ   0.475622   -30   0   EM12mp   +30   1.000 
WA3TTS   EN90xn   1743   1083



On the equipment side, I made a comparison measurement between the RAY6 DBM 
converter LO level on the IF out versus my modified Heath HD1420 VLF 
converter Friday morning. The LO level on the IF output of the RAY6 is -26 
dBm, whereas the Heath HD1420 LO IF level was -38 dBm. So it is possible 
the -26 LO level at 3.0 MHz is effecting the blocking dynamic range of the 
front end transistor of my FT-817 IF radio.

Thur morning I had rechecked the output level of my 2N5109 single ended 
Norton 10 dB gain LO driver amplifier. Harmonic content seemed high, so I 
swapped the 3 dB pad between the LO driver output to the RAY6 to the driver 
amplifier input. Immediate improvement between the second and third LO 
harmonic level was realized as shown below....

http://i1296.photobucket.com/albums/ag19/wa3tts/IMG_3815_zps553e6909.jpg

Apparently the +15 dBm output level from the OCXO was a bit too much for the 
2N5109 driver amplifier. Moving the 3dB pad to the input side of the 
amplifier provides a much improved response.


With the 3dB pad between the RAY6 and the driver amplifier output, the 
second and thrid LO harmonics were the same level -40 dbm (center graticule 
line of SA display---not shown). I had noticed a similar response when the 
ZLW-1 +7 DBM was driven at a +10 level. Since the single-ended common base 
Norton amplifier is essentilly and "active transformer", the theory is that 
the input impedance is replicated at the output. That would appear to be the 
performance case in this instance. The next logical step would be to get my 
1 dB step attenuator in line between the OCXO and driver amplifier to find 
the sweet spot and then guesstimate the best LO level for minimum mixer 
harmonic output content vs lowest mixer conversion loss....

Thanks for the bandwidth, 73, Mike, wa3tts

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