----- Original Message -----
From: "Jim Thomson" <email@example.com>
To: "Carl" <firstname.lastname@example.org>; <email@example.com>
Sent: Saturday, February 05, 2011 7:59 AM
Subject: Re: [Amps] What to buy?
> From: "Carl" <firstname.lastname@example.org>
> Sent: Friday, February 04, 2011 6:24 PM
> To: "Jim Thomson" <email@example.com>; <firstname.lastname@example.org>
> Subject: Re: [Amps] What to buy?
>> ## I have given up on torroids for tank coils on the low bands. I have
>> found some small diam, edge
>> wound ribbon coil stock that works the best for low band work. 3/8" edge
>> wound ribbon [.072" thick]
>> is the same as .28" tubing for current handling. 1/4" ribbon [ also
>> .072" thick] is ample in most cases
>> and is the same as .2" OD tubing. A friend also gave me a bunch of air
>> dux.. that uses 8 ga wire.. and the
>> wire was copper..and not the usual tinned material. These are things of
>> beauty. I didn't know you could
>> get coil stock in 8 ga wire.
>> Jim VE7RF
>> The NCL-2000 used one length #8 AirDux for 80-10
> ## The drake L4B's use 8 ga tinned solid wire for 80+40M. That coil
> runs stone cold on both bands.
> They used 1/4" silver plated tubing on 20-15-10m...which runs blazing hot
> on 15+10m. One would have
> thought that on 15m...that the heat was migrate into the remainder of the
> 20-10m coil..but it doesn't. Using
> the footswitch and my finger on the 15m tap...it's hot. Move one turn
> over into the unused part of the same coil
> and it's barely luke warm.....go figure. These days, I use a Fluke 62 ir
> when doing heat tests. The steel top lid on the
> L4B, IMO..is too close to the 20-10m tubing coil. With the top lid
> removed, the C1 cap has to be increased a bit.
> The torroids really save you nothing, space wise..VS airdux. The torroids
> can be mounted closer to metal..and that's
> about it. Torroids run way too hot, even 3 x T225-2B's, stacked.
> Jim VE7RF
If toroids run too hot there is something too wrong with the design. Ive
been using a stack of T225-2B's for decades in adding 160M to several amps
in the old 2000W PEP INPUT and 1200W output range.
The #8 in the NCL-2000 doesnt deform the plastic even on 10M in contests. I
used to run it full bore for over 20 years, even on CW and the coil still
looks good. These days its been ressurected as part of the vintage SSB
If a T-225B is too small there are plenty of bigger ones available. Ive
stacked T-400's and 520's when I was building serious amps for folks.
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