[Amps] Two quick loading questions

[Bob Maser]

Full smoke out the door with an eye on the grids is the best way to tune a 
GG amp. KISS in full force.
Bob
----- Original Message ----- 
From: "Rob & Terri Sherwood" <rob at sherweng.com>
To: "R.Measures" <r at somis.org>; "Donald Kessler" <ki6sz at earthlink.net>
Cc: "amps-contesting.com" <amps at contesting.com>
Sent: Wednesday, February 09, 2005 10:20 PM
Subject: Re: [Amps] Two quick loading questions


>I have always been puzzled by the "maximum smoke" tuning recommendations of 
>some amps, AL-80A or B, for example.
> A single 3-500Z in linear service is rated at 400 mA plate current. (350 
> mA in class C).
> When I used to run a Measures/Kessler modified TL-922A (pair of tubes), I 
> tuned it as follows:
> 800 mA on the plate and 150 mA on the grid for SSB.  If I was running CW, 
> I tuned it for 200 mA on the grid.
> It was very easy to adjust the plate tuning for a grid current peak, as 
> opposed to trying to see a broad plate current dip.
> When tuned for the 800/150 mA conditions, the amp was very linear at 800 
> mA, and would saturate at something approaching 900 mA.
> I always monitor my amps with a Tektronix scope, and set the RF envelope 
> at 6 divisions at the above plate/grid current conditions.
> With a modest amount of speech processing to control the peaks from the 
> exciter, it is easy to see the linear flattop a bit above the 6 scope 
> divisions.
> Set the drive on the exciter to peak the amp at 6 divisions, and I am 
> completely confident I have a clean signal.
> Without a scope, it is difficult to know how hard to drive the amp.  The 
> ballistics of analog meters is all over the map.   My Alpha 76PA was very 
> different from my TL-922A meters. My present Alpha 99 and 89 amps, even 
> with LED metering, are not peak reading devices.  In these two Alpha 
> examples, if the power output is set for 1500 watts key down, the LED 
> meters read about 800 watts on voice peaks.
> R.Measures wrote:
>
>> Tuning for max P-out with max-drive is more important than looking for a 
>> dip.
>>
>> On Feb 9, 2005, at 12:39 PM, George KB2Z wrote:
>>
>>> I'm sure I'm not the first to ask. I have searched in the archives and 
>>> did not find a solid answer. I apologize up front and am not trying to 
>>> waste anyones time. The directions from different  manufacturers dont 
>>> seem to answer one way.
>>> As I read the loading instructions for gg hf amps, (2x3-500) they should 
>>> be fully loaded at full power then the loading increased 5 to 10% to 
>>> lower the Ig and help stabilize the output. This seems to be where it 
>>> gets confusing for me.
>>>
>>> 1) After increasing the loading 5 to 10%, should the plate be re-dipped?
>>> 2) If drive is reduced from 100 to 50W, should the plate be re-dipped.
>>>
>>> Thanks in advance,  George KB2Z
>>>
>>> _______________________________________________
>>> Amps mailing list
>>> Amps at contesting.com
>>> http://lists.contesting.com/mailman/listinfo/amps
>>>
>>>
>>
>> Richard L. Measures, AG6K, 805.386.3734.  www.somis.org
>>
>> _______________________________________________
>> Amps mailing list
>> Amps at contesting.com
>> http://lists.contesting.com/mailman/listinfo/amps
>>
>>
>
>
> _______________________________________________
> Amps mailing list
> Amps at contesting.com
> http://lists.contesting.com/mailman/listinfo/amps
>