[HBR] WARC coils

[Hopperdhh at aol.com]

Gentlemen,

According to my calculations it should be possible to make 160 meter coils.  
The signal circuits will be the hardest because the percentage of frequency is 
greatest there.  If your tuning cap is 6.6 to 23 pF, you need 99.74 uH and a 
padder (including strays) of 56.26 pF.  This is somewhat less stringent than a 
standard broadcast coil that tunes 530 to 1610 with a delta C of 365 pF.  
There you would need 220.28 uH with a padder (including strays) of 44.36 pF.  I 
cite this example to show that if you can achieve a greater inductance with 
less stray capacitance, then you can certainly make the 160 meter coils.  You 
would of course not tap the coil, but connect the variable cap to the top of the 
coil.

The oscillator would be much easier because it tunes 3.4 to 3.62 MHz.  If you 
don't tap the coil like Ted did, you would need 99.74 uH and a padder 
(including strays) of 56.26 pF.  Exact calculations for the tapped coil arrangement 
are not possible as far as I know.  I'm not sure what the design criteria was 
that Ted used.  Does anyone know the answer?

I would start with a set of junk BC coils and prune off turns to get the 
right inductance.  In other words, you may need to use a universal coil winder to 
keep the distributed capacitance down.  Although it wouldn't hurt to try a 
solenoid winding and see what happens.  I am fortunate enough to have a Boonton 
Q-Meter which really helps with this kind of work.

Unfortunately I don't have a receiver to experiment on, but I am confident 
that you could make it work if your tuning cap is 6.6 to 23 pF.

Respectfully,

Dan K9WEK


In a message dated 12/25/2006 9:06:30 AM Eastern Standard Time, w2dgb at ptd.net 
writes:
I recall reading one of TC's quotes on the subject of 160 M coils, as this 
question has come up before.  He said that the LC combo wouldn't permit 
tuning the 160M band (or the BC band)  The cap is too small.  Possibly you 
could make something that would tune a small part of the band if you are 
adventurous.

Merry Christmas to all!

Bill Fizette  w2dgb


----- Original Message ----- 
From: "TC Dailey" <daileyservices at qwest.net>
To: "HBR Receiver List" <hbr at mailman.qth.net>
Sent: Monday, December 25, 2006 1:45 AM
Subject: [HBR] WARC coils


>I think that sounds like a splendid project for you, Bob!
>
> Better yet - anybody ever make a set of SUCCESSFUL 160m coils?
>
> Tom - WØEAJ
>
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Visit the HBR Receiver Web Site with over 100 pictures of receivers and 
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