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Re: [Amps] Swan Mark 1 on 160 meters

Subject: Re: [Amps] Swan Mark 1 on 160 meters
From: MU 4CX250B <>
Date: Wed, 30 Jun 2021 18:51:52 -0400
List-post: <>
Normally, toroids are self-shielding, which means they are hard to
couple into inductively. In a bandswitched amplifier, the inductive
loop coupling into the toroid is normally created by the wiring
between the toroid and the bandswitch wafers. Careful layout of the
bandswitch wiring can minimize this problem.

In my experience the more common problem is a high voltage flashover,
where the low 10m inductance couples into the higher inductance of the
160M coil, acting like a step/up transformer. I have not heard of the
160M toroid overheating because of this mechanism.
Jim w8zr

Sent from my iPhone

> On Jun 30, 2021, at 2:33 PM, Jim Brown <> wrote:
> On 6/30/2021 12:37 PM, gudguyham wrote:
>> How does a torrid used on 160/80 meters get hot on 10 meters if it’s shorted 
>> out?
> No short answer. Depends on what the toroid is made of and the circuit.
> My post was simply intended to fill in the huge gaps in understanding these 
> materials by hams. I learned nothing about them in school, even though they 
> were widely used long before I graduated from U of Cincy in '64.
> 73, Jim K9YC
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