Re: [IRCA] Loops and the SRF-59

[satya@xxxxxxxxxxxx]

Hi all:

I have a couple Terk loops (essentially the same as the Radio Shack loop)
- placing the 59 inside gives the maximum gain: probably all you would
ever want in most situations.

However, placing it at the foot of, and in line with, the loop:

          ---------------      ------
         |     LOOP      |    |  59  |
          ---------------      ------

gives somewhat reduced gain, but narrows the bandwidth for more
selectivity :-).  The optimum separation between the 59 and the loop
appears to be about 2 inches: adjacent slop goes down but the signal is
still quite high.

THEN, rotating the 59 in this position allows for some pretty mean phased
nulls.  I have found that first pointing the loop such that the pest is
nulled to the extent practical works the best: the 59 then inductively
picks up mostly DX signal from the loop, and whatever pest signal the 59
picks up can be cancelled out by the pest signal picked up on its own
little ferrite.  On the Terk, there is a "line out" jack that can be
connected to a spotter receiver, which can be used to find the best null
orientation for the loop, after which the 59 can be brought in for the
final kill.

Note that the Terk literature indicates that the loop has a 300 ohm
output, and the supplied parallel-wire cable is designed for that. 
However, I have found that the output is actually around 50 ohms, and
simply connecting a 1/8" mono coaxial cable to the "line out" jack works
the best!  The output is still rather low, and I have a Palstar AA30 and
MFJ-1020C that can bring the loop output up to a decent level.

Sometimes the phased null occurs when the 59 is sidled up along the base
of the loop:

          ---------------
         |     LOOP      |
          ---------------
                         ------
                        |  59  |
                         ------
or somewhere in between.  I still have to rotate the 59 a bit regardless
of where is ends up at.  Occasionally I rotate the 59 in azimuth as well.

73 - Kevin




>>>> Colin wrote: I pulled out my oak-frame 5' loop (from being moth-balled
>>>> by Wellbrook!) - rewound the wire, added the capacitor..and Wahoo!
>>>> Does
>>>> this loop ever cook with the SRF59, the Sangean DX200VX, et al.<<<
>
> Interesting idea. My two Radio Shack loops are at my Burnt River ON DX
> site,
> so I will have to wait to try using them in conjunction with my SRF-59. I
> use these loops with my two Sangean ATS 909 radios by simply
> putting the radio on a plastic book reader and placing the radio and book
> reader in the middle of the loop. I wonder what I might expect using the
> SRF-59. Though I do think the SRF-59 might perform as well or maybe even
> better on its own; perhaps the loop would act as some sort of phasing
> mechanism and enhance the SRF-59? I'd be curious if anyone tries this;
> otherwise I will wait a week or two.
>
> Saul
>
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