On Jul 31, 2005, at 11:54 AM, Bob Maser wrote:
> I disagree with your note 5. Tuning the tune and load controls for
> maximum smoke will sometimes give you too much grid current.
Bob -- How much is too much?
> 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@somis.org>
> To: <rees.a@btconnect.com>
> Cc: <amps@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
>>>
>>>
>>> _______________________________________________
>>> Amps mailing list
>>> Amps@contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
>>>
>>
>> Richard L. Measures, AG6K, 805.386.3734. www.somis.org
>>
>> _______________________________________________
>> Amps mailing list
>> Amps@contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>
>
>
>
Richard L. Measures, AG6K, 805.386.3734. www.somis.org
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