[Amps] Ameritron AL-80B

[mikea]

On Tue, Sep 13, 2011 at 10:48:19AM -0400, Mitch Cox wrote:
> Sounds like a tank circuit issue. You might check to see if the tank coil is tapped correctly, From memory I think it should tap on the 4th or 5th turn for ten meters. It could be something else but that is what I would look at first and then to see that either of the capacitor (C1 & C2) plates are touching or arcing on ten.
>   ----- Original Message ----- 
>   From: s-roabr at online.no 
>   To: Mitch Cox ; amps at contesting.com 
>   Sent: Tuesday, September 13, 2011 1:25 AM
>   Subject: Re: [Amps] Ameritron AL-80B
> 
> 
>   Yes, all seems normal in Swr... the tube goes cherry red... so some mismatch....other pa gives 1kw on same antenna...
> 
>   sent by HTC
>   LA6FJA K3RAG Stein Roar Brobakken
> 
>   ----- Reply message -----
>   Fra: "Mitch Cox" <ww4cox at embarqmail.com>
>   Dato: tir., sep. 13, 2011 00:36
>   Emne: [Amps] Ameritron AL-80B
>   Til: <amps at contesting.com>, <s-roabr at online.no>
> 
>   Have you looked at the SWR between the radio and amp on 10 meters?
>    ----- Original Message ----- 
>    From: s-roabr at online.no 
>    To: amps at contesting.com 
>    Sent: Monday, September 12, 2011 6:18 PM
>    Subject: [Amps] Ameritron AL-80B
> 
> 
>    Hi
> 
>    I have a AL-80B, all bands is ok. But it have max 300w on 10m. Any idea how to find out why?
>    Any one have had same problem?
> 
>    sent by HTC
>    LA6FJA K3RAG Stein Roar Brobakken

Low power out on 10m and a cherry red plate, together. 

The cherry red plate indicates that _LOTS_ of power is moving through
the tube, if I'm not sorely mistaken. But the low power out on 10m is a
sign that that power isn't being generated in the desired band -- which
means it's being generated somewhere else. 

I suspect parasitic oscillations, and suggest that it may be time to
neutralize the final on 10m. 

I may be completely wrong, and 180 degrees off course. If so, then
someone please point out (GENTLY!) where and how. 

-- 
Mike Andrews, W5EGO
mikea at mikea.ath.cx
Tired old sysadmin