[Lowfer] DK7FC alert 136.172 & more bench tinkering

[Michael Sapp]

Dex & Jay (& All):  AOS around 0230......diplexer seems to help as I am 
splitting the converter output to capture DK7FC on 137.162 and

running 600M WSPR2 on my other receiver simultaneously.  Prior attempts to 
do that usually did not work that well....


http://i1296.photobucket.com/albums/ag19/wa3tts/may414a_zps17c9767f.jpg


I tossed the converter LO filter as various SA tests showed the DBM and 
diplexer with a pad at the LO port to attenuate excess LO power and improve 
match worked best (also as Jay suggested).

http://i1296.photobucket.com/albums/ag19/wa3tts/CNVTESTS_zpsd32c6f22.jpg


I built up another 3.0MHz T-bridge diplexer with a Q =1 in 50 ohm strip line 
technique and tried it on the LO port. It did reduce the 6MHz harmonic 2dB 
at the

DBM IF out port,  but otherwise it was not worth the effort in this 
frequency range as the other mixer product levels did not change much.

Return loss was in the mid 40s to 50 range, mid 30's at  2.0 ~ 4.0 MHz.

Perhaps not much practical improvement between 30 and 45 dB return loss, but 
the second build showed using strip line technique matters even at 3 Mhz....

Second build diplexer is now on the LF converter IF out port, since it has 
better specs and enough BW. I'll try a Q=5 or 10 diplexer rebuild of the 
first version as time allows....

Worthwhile learning experience for me.......tnx for the bandwidth. 73, Mike 
wa3tts