[Lowfer] LW BCs tonite in EN90xn & recent LF bench tinkering

[Michael Sapp]

Hi All: Several LW BCs copied this evening, nice to see the T/A path to EU still open this late.....

https://www.youtube.com/watch?v=HOE5jmqgC5E&list=UUfTfag2dJYGGilPLMs0uVXw


The LO filter is a recent add-on and looks like this....

http://i1296.photobucket.com/albums/ag19/wa3tts/isotemp2_zps991e55f2.jpg


And the diplexer looks like this....

http://i1296.photobucket.com/albums/ag19/wa3tts/DIPLXR_zpsb092e34e.jpg


I looked at the output on the HP141T SA with only the LO filter added to the mixer and the net effect was to lower the 2nd harmonic 3 dB but increased

some of the higher order product levels several dB ---although still 30~40 dB down from the 3.0~3.5 MHz IF of the converter.  Perhaps a second

diplexer for the LO would be a better alternative for mixer IMD improvement vs the LO filter,  since the OCXO is already -44 and -62 dB down on 2nd and 3rd harmonic output on it's own

(the harmonics regenerate anyway inside the DBM).....

Also interesting to look at the IF xmas tree output on the SA and see the how sideband products cancelled in the DBM either side of the 2nd & 4th IF harmonics with the converter connected to the antenna....

http://i1296.photobucket.com/albums/ag19/wa3tts/IMG_3760_zpsfcd93207.jpg


Sorry I did not get a image capture of the converter output on the SA yet with the diplexer in-line. It did show 30dB return loss from 1.7 to 30 MHz on my MFJ-259B

with the exception of being around 28 dB RL in the center of the 3.3 MHz IF passband.  Insertion loss looked to be about 1/2 to 1 dB range in the IF passband .  LO filter RL was 25dB at 3.05Mhz and

20dB at 3.0 MHz on the MFJ analyzer, so it still needs a slight capacitor tweek....


Sure felt good to melt some solder after several weeks of constantly jockeying federal forms in my not-so infinite "free" time.....

Thanks for the bandwidth, 73  Mike, wa3tts