Martin:
Old Tube type A.M. radios from the 50's to the early 70's will be a very good
source for high value,
slug tuned Inductors.. I have 2 coils I use to tune my 160 meter Windom for 136
KHz.. Each coil is
a 2 section - PI wound coil, tunable by a ferrite slug.. With each section
connected in series; I have
a total of 3.2 mH of Inductance for each coil.. I use an Air Variable capacitor
with the Inductor to make
a simple " L " network to peak the antenna for maximum signal voltage to the
radio.. It works well for me..
For illustration purposes, here is a link to a hand drawn diagram of my antenna:
http://ku4xr.webs.com/apps/photos/photo?photoid=145485293
73:
Andy - KU4XR - EM75xr - Friendsville, TN. USA
Coordinates: N: 35º 43' 54" - W: 84º 3' 16"
http://lwca.org/grabbers/ku4xr/
http://www.myspace.com/beaconxr
http://ku4xr.webs.com
http://lwca.org/community/YaBB.pl
----- Original Message -----
From: Martin Evans <[email protected]>
To: [email protected]
Cc:
Sent: Friday, January 13, 2012 4:23 PM
Subject: Re: LF: Tuning inductance for 137kHz receive.
Yes - I was given this tip by someone else yesterday, Kevin ( my apologies to
the original tipster - I'm in another location now, and can't recall who it
was!).
As you say, the problem is to find such a radio these days - though I'm
certainly going to look out for one because 0.3mH to 2.8mH is an ideal range to
have.
Martin. GW3UCJ
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> Here is one effortless method that I have used for years to tune a random
> wire for LF reception:
>
> First, find an old AM car radio that tunes with three ganged movable ferrite
> slugs and extract the tuning unit.
> The three coils are all shielded from each other and can be series connected
> in any order and polarity to maximise the total inductance. One unit tested
> here allows continuous variation from 0.3mH to 2.8mH.
> On occasion, I have connected a fixed inductor in series to increase the
> maximum possible inductance.
>
> I guess the major problem is to find a suitable old car radio - not variable
> capacitor tuned.
>
> Kevin ZL4MD
>
>
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