[Amps] Alpha 87a

[Dick Green WC1M]

The 87A input network uses air-wound coils on 10m and 12m, so they'd have
less adjustment range than the iron toroid coils used on the other seven
bands. In fact, the 10m coil has only two turns! 73, Dick WC1M

> -----Original Message-----
> From: Tom W8JI [mailto:w8ji at w8ji.com] 
> Sent: Monday, January 01, 2007 6:57 PM
> To: Amps Amps
> Subject: Re: [Amps] Alpha 87a
> 
> > with a slug like the TL-922A or  your 30L1, for example. 
> > Maybe one can
> > play with the spacing of the input torroids, but I doubt 
> that is easy 
> > or has much range.
> 
> I was surprised by how much inductance range iron cores 
> produce as turns are bunched and spread.  I've measured 
> various iron cores (T94 size iron toroids) and they can have 
> about 30%  inductance change from fully spread to fully 
> bunched turns. This is also measured far from self-resonance, 
> so it is not the turn-to-turn capacitance at work.
> 
> That actually was a fix for some Dentron gear. Just squeeze 
> the turns together and readjust the capacitors for lowest SWR 
> on the input.
> 
> 73 Tom 
> 
> 
> 
>