----- Original Message -----
From: "Jim Thomson" <jim.thom@telus.net>
To: <amps@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@jeremy.mv.com>
To: "Bill Turner" <dezrat1242@yahoo.com>, "Amps" <amps@contesting.com>
Subject: Re: [Amps] 160M PI network Toroidal Coil
----- Original Message -----
From: "Bill Turner" <dezrat1242@yahoo.com>
To: "Amps" <amps@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
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