[Amps] 160M PI network Toroidal Coil

[Carl]

----- Original Message ----- 
From: "Jim Thomson" <jim.thom at telus.net>
To: <amps at contesting.com>
Sent: Monday, October 07, 2013 5:02 AM
Subject: [Amps] 160M PI network Toroidal Coil


> 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.


** There is no "correct" toroid or the number stacked. Anything over a pair 
of T200-2's or a single T200A is overkill at SB-220 power levels for SSB/CW.

The T-225/225B (there is no T225-2A) size buys you absolutely nothing over 
the 200 size except a few more turns of wire of the same diameter. 
Inductance per 100 turns is identical between the single heights as well as 
double heights.
If anybody wants T225-2 or -2B cores I have many at a much lower cost than 
Amidon, Palomar, etc.

Carl