[Amps] Best way to tune a Dentron ML2500 ?

[Bob Maser]

I disagree with your note 5.  Tuning the tune and load controls for maximum 
smoke will sometimes give you too much grid current.  My Alpha 78 in the 
manual mode, for instance, requires a slight clockwise tweak in order to 
bring the grid current down to acceptable limits.  With the 8874's 
replacement cost, you can bet I watch grid current like a mother hen.

Bob  W6TR
----- Original Message ----- 
From: "R.Measures" <r at somis.org>
To: <rees.a at btconnect.com>
Cc: <amps at contesting.com>
Sent: Sunday, July 31, 2005 2:43 PM
Subject: Re: [Amps] Best way to tune a Dentron ML2500 ?


>
> On Jul 31, 2005, at 11:16 AM, Adrian Rees (M1LCR) wrote:
>
>> Whats the best way to tune a Dentron 2500 Linear, for max power and
>> longest
>> tube life ?
>
> For best tube life:
> 1.  decrease the Q of the VHF suppressors in the anode leads.
> 2.  decrease the VHF-Q of the lengthy lead that connects the Tune-C to
> the anode HV RFC.
> 3.  Tune the amplifier up for SSB with dits or a tuning pulsar.
> 4.  do not drive the amplifier with more than c. 60w -- unless of
> course you have more than a couple of dozen spare tubes.
> 5.  tune for max out with c. 60w drive.  When the drive is right,
> tuning for max RF out always produces safe grid-I.
>   - note - For key down / RTTY / FM service the absolute max current
> rating is 350mA per tube.  Exceeding this rating can strip the oxide
> coating off of the cathode.  The SSB rating of the cathode is 500mA on
> voice peaks.
>>
>> What should the Grid Current be at maximum power ?
>
> Tuning as above will insure that most of the electrons go into the
> antenna and not into the grid.
>>
>> Thanks
>>
>> Adrian Rees
>>
>>
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>>
>>
>
> Richard L. Measures, AG6K, 805.386.3734.  www.somis.org
>
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