Hey All,
Last night I decided to try out something that I had seen that originally used two stand alone large/outboard home brew ferrite bar/ tank "antennas" for Co Channel "pest control" application .
The idea was to fully null the pest with the receiver's ferrite first.Then place one outboard bar to boost the desired station coupling it along SIDE of the rig's internal ferrite and the other outboard bar off the END of the rig's ferrite to deepen the pest's null.
Since I don't have any big ferrite, I decided to try two basic/no jack model Select- A -Tennas instead. The results were intriguing.
I tuned into "My favorite Co Channel " (starring Ray Walston and Bill Bixby
) 740 for CFZM vs very local WJIB which was still huge at 5 watts night power.
The expected orientation did not pan out at all, at least on the Super Radio I and these air core loops.. Trying to deepen JIB's attenuation by aligning one of the loops null to the rig ferrite null did nada, at least for me in this case. Changing the distance , etc, didn't work at all. All action was attained by coupling both loops peaks "broadside" to the ferrite.
Odd, since loop peaks are much more "vague" than the "black hole " of the null (after fifty years of playing around I am STILL amazed by radio !).
The best configuration seemed to be having one loop at one end of the ferrite and the other at the opposite end and on the opposite side of the radio cabinet. That way both loops "boosted" the SR-1 for Zoomer but had as much physical separation as possible.The only null action was in the radio's ferrite.
Even MORE wacky was that loop closer to JIB loop "liked" a more "conventional" 90 degree coupling angle, yet the other one ""needed" to be at 45 degrees in order for the entire set up to work. And of course like previous single loop experiments, all placements (rig, loop 1 and loop 2) HAD to be exact to within 1/8 to 1/4 ". If any parameter was off, even a tiny bit, you heard zilch (except a slight or moderate JIB artifact depending on what they were playing).
Zoomer rolled up and down (as usual), but never really came up to much beyond weak or a bit better , even after a while of being parked on frequency. Zoomer's transmitter antenna null is in my direction (not "optimal"), and also propagation seemed kind of crumby as well.
I repeatedly tried it "barefoot" , going over to only the JIB closer loop during these marginal conditions. No dice.Every time I tried.But when the second loop was brought back in, Zoomer came back in (WHEN the QSB "cooperated").
So the takeaway ,at least to me under these conditions and set up , is that the second loop WAS useful, even in this situation of two stations nearly 180 off from each other (which is a "challenge").
The next target is 650 with regional WSRO vs THE LEGEND (WSM). Both are ALMOST in the SAME direction from me. If I can tame SRO even a tiny bit and bring SM up a TAD , I'll call it a big victory. "We'll see".
BTW, I really miss my MFJ 1026
.
Your mileage may vary on all of this and no warranty is implied
.
K
Topic: Dueling Selecta- A Tennas (NOT Banjos) (Read 2677 times)
