[Lowfer] MF ummer Solstice DX

[Michael Sapp]

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