[AMPS] Re: [CQ-Contest] Ameritron AL1500x efficiency ?

Rich Measures measures@vc.net
Wed, 1 Oct 97 08:09:47 -0800

>Chris W Tran wrote:
>> Tuesday 30th September 1997
>> Hello all
>> One of our contest group - Keith Kerr GM4YXI - has just purchased
>> an Ameritron AL1500x and there appears to be a problem with
>> efficiency - specifically on 20m.
>> On 80m, 40m and 15m, efficiency = 54 % approx.
>> On 20m, efficiency = 42 % approx.
>> We've followed the manufacturer's tune-up method carefully,
>> and also tried numerous combinations of loading, drive level etc.,
>> but cannot improve significantly on this figure of 42 %
>> I think the inefficiency could be caused by :-
>> Design fault - e.g. poor tank cct. design or poor plate choke
>> design, etc.
>> Manufacturing fault - tapping point in wrong place, etc.
>> We've looked at the plate circuitry carefully and none of
>> these reasons seem possible.
>> Any ideas ?
>> Keith is contacting Ameritron for their suggestions of course.
>> Please reply to :-
>> <chris.tran@zetnet.co.uk>    or    <k.kerr@abdn.ac.uk>
>> Thanks - 73      Chris Tran GM3WOJ
>Hi Chris,
>  Have you tried tuning the amp into a dummy load on 20 meters? ...snip...

I did not receive the original post, Chris. 
-   Wattmeters are calibrated for a matched condition.  Add SWR and the 
accuracy is compromised.  What was the SWR looking into the load when you 
took the P measurement on 20m?  

Also, how is an AL-1500x different from an AL-1500?  Is the AL-1500x 
"neutralized"?  Does it use a VHF parasitic-oscillation suppressor? 

R. L. Measures, 805-386-3734, AG6K   

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