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Re: [Amps] Swan Mark 1 on 160 meters

Subject: Re: [Amps] Swan Mark 1 on 160 meters
From: Jim <>
Date: Wed, 30 Jun 2021 07:34:27 -0500
List-post: <>
DO NOT use toriods. I speek from experiance. Had a reaction when on 10 meters with my 8877 amplifier. The 160 meter toriod coils would start smoking when on 10 meters. I was using a shorting switch.

Use a small (wire gauge, #16 is all that is required) coil. 3-4" in diameter. The closer the turns are together, the more inductance.

Measure the current tank inductance with all coils in the circuit, (80 meters selected) then simply add that much more inductance with your 160 meter coil.


Jim W7RY

On 6/29/2021 6:29 PM, John Keating wrote:
I have a stack of two T-225A-2 as the low band tank coil in my QRO HF2000 (2 x 
3-500z). It does get quite warm on extended key down but so far no failure.


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From: Amps <> on behalf of Bill Smith via Amps 
Sent: Tuesday, June 29, 2021 7:24:40 AM
To: <>
Subject: [Amps] Swan Mark 1 on 160 meters

Considering adding 160 meters to my Swan Mark 1 amplifier.  The power supply 
and RF deck were overhauled in 2003.   At that time a new transformer was also 
added to replace the shorted out original one.  Since the RF deck was barren 
when I got it I added a Radio Switch 86 bandswitch and new tank coils.  It 
works well 80-10 meters using the original 3-400Z tubes.
Thought I would use the instructions for adding 160 to the Heathkit 220.  The 
bandswitch has an extra contacts I could use so no relays would be required.
My question is would Toroid core type tank coil work in this application or 
would it overheat?  I've seen recommendations for using a Amidon T-225A-2 
powdered-iron toroidal core.
Thanks,Bill KO4NR
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