OK, I give up; what is a BA rig?
73,
K5GW
In a message dated 8/10/2009 2:00:34 P.M. Central Daylight Time,
km1h@jeremy.mv.com writes:
10X the RL was the way it was done and all the old BA rigs had 1 to 2.5mh
plate chokes. That was for the old style series fed plug in coil tanks.
When parallel fed pi nets came along the recommendation was for 4-5X. and
it
varied depending on who was writing it.
The first widespread mini choke came out with the SB-200, I believe, and
at
90uH.
Carl
KM1H
----- Original Message -----
From: "Bill, W6WRT" <dezrat1242@yahoo.com>
To: <amps@contesting.com>
Sent: Monday, August 10, 2009 2:00 PM
Subject: Re: [Amps] plate bypass capacitor
> ORIGINAL MESSAGE:
>
> On Mon, 10 Aug 2009 16:55:58 +0000, Manfred Mornhinweg
<manfred@ludens.cl>
> wrote:
>
>>
>>> I believe that the recommended impedance of the RF choke should be 10
>>> times
>>> the plate load impedance of the amp not the reactance of the plate
tune
>>> capacitor.
>>
>>It's correct that the load impedance and not the capacitor impedance is
>>the base, but the 10 times factor is purely a rule of thumb, and very
>>wide deviations are possible.
>
> REPLY:
>
> Ten times the plate load impedance?
>
> For the typical 160 meter amp running 3 kV and 800 mA with a plate load
> impedance of aprox 2200 ohms, that would require a choke with a
reactance
> of
> 22,000 ohms, or about 2000 uH. I have never seen a design with that much
> inductance for the plate RF choke, or anywhere close to it..
>
> Are you sure you don't mean 10x the reactance of the tune cap? That
seems
> to be
> pretty much the standard.
>
> 73, Bill W6WRT
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