[Amps] 160M PI network Toroidal Coil

[Jim Thomson]

Date: Sun, 6 Oct 2013 09:28:36 -0400
From: "Carl" <km1h at jeremy.mv.com>
To: "Bill Turner" <dezrat1242 at yahoo.com>, "Amps" <amps at contesting.com>
Subject: Re: [Amps] 160M PI network Toroidal Coil


----- Original Message ----- 
From: "Bill Turner" <dezrat1242 at yahoo.com>
To: "Amps" <amps at contesting.com>
Sent: Saturday, October 05, 2013 11:43 PM
Subject: Re: [Amps] 160M PI network Toroidal Coil


> ORIGINAL MESSAGE:          (may be snipped)
>
> On Sun, 06 Oct 2013 00:25:36 +0000, Manfred wrote:
>
>>You are wrong regarding the loss. The loss isn't "essentially zero",
>>unfortunately. Such a coil will likely end up having a Q between 300 and
>>350, perhaps lower if other metal objects are too close to it, or if it
>>uses some lossy support. Now if the loaded Q of the tank circuit is 12,
>>as is often done by design, then the coil will loose about 4% of the RF
>>power. At 1500W output that would be 60 watts, which is enough to make
>>that coil very hot, unless there is a strong stream of air cooling it.
>
> REPLY:
>
> I stand by what I said. I have such a coil in my homebrew 8877 amp using 
> #4
> wire and it runs barely warm with the key down. I call that "essentially
> zero" in the sense you'll never notice it.
>
> 73, Bill W6WRT

However the thread is about a SB-220 which may make 1300W PEP on a good day 
and will never be used for RTTY at more than half that due to the wimpy PS.

A pair of T200-2 toroids works fine for that as well as the thousands of 
Alphas and other amps that have used them at up to twice the power.

Carl
KM1H 

##  The correct Torroids to use are T225-2A    these are the ones that when laid flat on 
a table, are 1 inch tall.   The T225-2  is only .5 inch tall.    3 x T225-2A  stacked, end up being
2.25 inch diam x 3 inch long.   Then wiund with 8 ga wire.     Bare 8 ga wire is .128 thick....and
slightly thicker with the typ magnet wire. 

##  I have used airdux b4  for the entire 160m coil in 2 x 4-400A  160m amps.   I was given some
close spaced stuff, think it was 12 ga wire.  It was close spaced turns than you normally see. It weighs 
nothing and is no bigger than stacked cores anyway. 

##  Tinned 8 ga   wire runs  stone cold with 800 ma CCS plate current on 80 and also 40m.  This is
the case for a the coil wound on a grooved ceramic form... like what is used in the drake L4B. 
10 ga will run stone cold on 160m.  You don’t need 4 ga wire.
With 1500w rtty, torrids will diss  aprx 57 watts  whether 1-2-3  cores are used... T-225-2A.   
If you want to run 1500w  rtty on 160m, Id suggest 3 x T-225-2A stacked.    For 1500w  cw-ssb,
use at least two of those cores. 

##  If you are going to convert a  monoband SB-220  to 160m,  I would not even mess with  torroids.
One piece of airdux using 12 ga  wire, close spaced is more than ample for the job..and it wont dissipate
a ton of heat like torrids. 

Jim,  VE7RF