Re: [IRCA] Working on the problem

[Tim Hills <thills@xxxxxxxxxxxxx>]

Thanks Russ.

The  mixed loop is more for fine tuning the preamp than any permanent 
solution, leftover 1x2 from another project and notched for the wires 
with a miter saw. Quick and dirty. Since the varactors are switched 
between the 2 loops the smaller loop doesn't seem to interfere with the 
larger one though below about 5MHz there doesn't seem to be a null on 
the smaller one. I have some Litz coming and plan on doing a 3' MW loop 
separate from any other antennas.

Null is sharp on MW and I can detect a station at 1120 with very little 
of 1140 blasting in here so the Q isn't that bad either. I think 
replacing the 26 gauge vinyl covered wire taken out of some old Cat 5 
with Litz and getting rid of the inner loop would be a big improvement 
on it's own.

The Preamp is sensitive enough that I get decent reception by hooking 5' 
of wire to each side through a 33pF cap on HF feeding my modded S350DLX. 
Hmmm, 10' length of leftover Copper pipe.. I think a stealthy vertical 
dipole is in mu future :D

I have a roaring sinus headache but my next experiment is to use the 
inner 4 turn CT winding as the pickup for the MW loop. I'll try that 
this evening if this headache goes away..

Tim

On 4/10/2011 8:48, Russ Edmunds wrote:
> Using the two loops on the same frame will degrade the performance for the MW portion and probably the SW portion as well. This is because the proximity of the windings pretty much ensures that each will 'see' the other and therefore the resulting patterns will be somewhat skewed and the nulls likely reduced.
>
> I've used two air core MW loops in my basement shack - one 4' the other 2' for over 20 years and found that I needed to keep them about 4' apart in order to minimize unwanted interaction.
>
>
> Russ Edmunds
> 15 mi NNW of Philadelphia
> Grid FN20id
> <wb2bjh@xxxxxxxxx>
> FM: Yamaha T-80&  Onkyo T-450RDS w/ APS9B @15'; Grundig G8
> AM:  Modified Sony ICF 2010's barefoot

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