[Amps] 160M PI network Toroidal Coil

Jim W7RY w7ry at centurytel.net
Sun Oct 6 18:53:51 EDT 2013


There is little to no RTTY activity on 160 meters.

73
Jim W7RY

On 10/6/2013 6:28 AM, Carl wrote:
>
> ----- 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
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