[Heathkit] HW-9 Toroids

[jeremy-ca]

In this respect toroids are the same as old traditional slug tuned and 
solenoid wound coils. Even Q Dope can shift inductance a little bit which is 
usually not enough to matter at HF.

Toroids come in two basic flavors, powdered iron and ferrite. Powdered iron, 
often a Micrometals product, have low permeability and are less affected by 
coating. These are often paint color coded at the factory. OTOH ferrites, 
Fairite Corp for instance,  have high permeability and coating can move 
their values quite a bit.

In either case if there are trimmer capacitors used to tune the circuits the 
coating shouldnt be a problem. If they are fixed tuned then leave them alone 
unless you have the equipment to realign.

Carl
KM1H



----- Original Message ----- 
From: <K4BEV at aol.com>
To: <heathkit at mailman.qth.net>
Sent: Wednesday, May 23, 2007 9:36 AM
Subject: [Heathkit] HW-9 Toroids


> I've been reading the Elecraft K2 list and note a discussion concerning 
> the
> toroids in it.
> It was stated that the should NEVER be varnished or coated with ANYTHING
> since this will shift the designed inductance.
>
> All of the toroids in my HW-9 are indeed varnished.
>
> Did they come this way from Heath, or did someone varnish them along the 
> way?
>
> I would suspect that if they came this way from Heath then they are most
> likely OK. Otherwise I may have a problem here.
>
> Also:
> They are color coded... Can anyone please verify which go with which band? 
> No
> mention of color is mentioned in the manual, just part numbers, and I'm 
> not
> finding the part numbers on the coils. I know the 80 meter coils are 
> correct
> (the only band with 3 - and they are all the same) but (it would seem to 
> me)
> that the toroids should get smaller as the freq goes up, but this isn't 
> the case
> with the 40 and 15 meter coils.
>
> The radio is still dead... A bit of experimentation indicates that most of
> the soldering joints were made by melting the solder on the iron instead 
> of on
> the joint. So now I'm in the process of unsoldering everything, seating
> components flush with the boards, verifying that they are correct, and 
> resoldering
> them. What fun ;-)
>
> The "black stuff" mentioned earlier smells like pine, so my guess is that 
> it
> is not acid core solder. Thanks to all for the tips about this!
>
> TNX es 73,
> Don - K4BEV
>
>
>
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