[Amps] Swan Mark 1 on 160 meters

[Jim]

Thanks
73
Jim W7RY

On 6/30/2021 11:36 AM, jim.thom jim.thom at telus.net wrote:
> Date: Wed, 30 Jun 2021 07:34:27 -0500
> From: Jim <jimw7ry at gmail.com>
> To: amps at contesting.com
> Subject: Re: [Amps] Swan Mark 1 on 160 meters
>
>
> <DO NOT use toriods. I speak from experience. Had a reaction when on 10
> <meters with my 8877 amplifier. The 160 meter toroid 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.
>
> <Simple.
> <Jim W7RY
>
> ##  Per KM1H, the infamous T-225A-2  is good for  850 watts per toroid, cw
> or ssb, contest mode.  Carl sez to use 2 of em for 1.5 kw ssb / cw.... and
> 3 of em if  RTTY /  data modes used.  Marv,  WC6W years ago, calculated the
> dissipation at  57 watts in total,  regardless of qty or toroids used.

I don't care what Carl what Carl sez.

73
Jim W7RY

>
> ##  I modified a hb  2 x 4-400  80-10m amp into a monoband  160m amp
> several yrs ago.  Each of those T-225A-2 cores are 2.25 inch diam..and  1
> inch tall.  With 3 of em stacked, the entire mess ends up  2.25 inch diam x
> 3 inch tall..and heavy...and that's before adding the tape and 10-12-14
> gauge wire.  Those cores are painted  red at one end, and are optimized for
> the lower bands.
>
> ##  Went to plan B..and  found a ton of airdux in my collection, 12 gauge.
>   I had  2 x almost identical coils, same 12 gauge, same diameter, and the
> only difference was one of em had slightly less spacing between turns.
>   The closer spaced coil also had higher measured inductance.
>
> ##  In my case, with  80-10m removed,  the  airdux coil  provided the
> entire required uh.  IF the coil uh is on the slightly...too small  size,
> it will still work, but the required tune and load cap values will have to
> be increased.
>
> ##  I designed it for an overall network Q of 10....which results in an
> input Q of  aprx 8..and  aprx an output Q of  2.   That relaxes the  tune
> and load C  requirements a bunch, and slightly more broadbanded.  Being a
> 160m  mono band amp, I then also had the luxury of  optimizing the plate
> choke, tune and load caps, and fixed padding on the air variable load cap.
> I used a  2200 pf broadcast variable  for the load cap.  Glass vac cap for
> the tune cap, which required no padding.
>
> ##  The small piece of airdux coil  weighs  nothing  vs the  3 x stacked
> toroids.... and zero heat from the 12 ga coil.
>
> ##  One of my  4 x L4B's is modified for  160m (160-10m), using the ag6k
> SB-220  160m mod method..for some of it.   I used a small  chunk of the
> same air-dux for the 160m  coil.
>
> Jim  VE7RF
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