[Amps] CW and High Voltage

[Will Matney]

Guillermo,

You'd have to tune it for the most power you could get with a compromise of the cleanest obtainable signal. In other words, you want the cleanest signal you can get, but the most power you can get with it. If the drive isn't cut back that far, re-tuning isn't necessary.

Best,

Will

*********** REPLY SEPARATOR  ***********

On 9/3/05 at 11:20 PM GGLL wrote:

>Even when re-tuning the amplifier with low drive, for maximum output, then
>(for the same plate voltage) the RL will be different from the optimum
>value
>for which the Pi tank is designed; you will have best output power for the
>drive, but what about efficiency  and harmonic suppression? (related to
>performance with full settings)?.
>
>Best regards
>Guillermo - LU8EYW.
>
>Will Matney escribió:
>> Steve,
>> 
>> Cutting the drive back too much will indeed cause a good size mismatch
>and would need to be fine tuned some. The reason being is when the power
>drops, the plate impedance changes accordingly. I myself don't see any
>fine tuning for this bad at all.
>> 
>> Best,
>> 
>> Will
>> 
>> *********** REPLY SEPARATOR  ***********
>> 
>> On 9/3/05 at 6:31 PM Steven Cook wrote:
>> 
>> 
>>>Thanks to all for your collective wisdom.
>>>
>>>I assume manufacturers added the CW position on older amps to meet FCC 
>>>limits on input power for that mode.
>>>
>>>Did this serve to maintain circuit Q, or were there other
>considerations; 
>>>e.g., power supply limitation, et al.
>>>
>>>Just seems weird to operate an output stage that is not fully "dipped
>and 
>>>peaked."  Old habits are hard to break!
>>>
>>>When I tune up my Kenwood TL-922 in the CW mode, and then decrease my 
>>>exciter output to around 50W, I notice a "HUGE" residual "dip and peak" 
>>>remaining in C1 and C2 respectively and a 200+ watt increase in output 
>>>power.  What's up with that???
>>>
>>>I guess I'll just have to get over the urge to "fine tune" things.
>>>
>>>Grrrrrrrr <smile>
>>>
>>>-Steve (WG7K)
>>>
>>>
>>>
>>>----- Original Message ----- 
>>>From: "Phil Clements" <philc at texascellnet.com>
>>>To: "'Steven Cook'" <sccook1 at cox.net>; <Amps at contesting.com>
>>>Sent: Saturday, September 03, 2005 12:01 PM
>>>Subject: RE: [Amps] CW and High Voltage
>>>
>>>
>>>
>>>>>Team,
>>>>>
>>>>>I've acquired an older Henry 2K-4, which only has one High Voltage 
>>>>>setting
>>>>>~ 3500V no load.
>>>>>
>>>>>It runs a pair of 3-500z triodes and will be driven with ~100W
>>>>>
>>>>>My question concerns running the amp at reduced output on CW and if it
>>>
>>>is
>>>
>>>>>better to:
>>>>>
>>>>>1.  Apply full drive, and adjust C1 and C2 until the desired level of
>>>>>output is achieved...
>>>>
>>>>This is never done under any circumstances on any mode!
>>>>
>>>>
>>>>
>>>>>2.  Apply full drive, adjust C1 and C2 until maximum power is achieved,
>>>>>then reduce the exciter drive without readjusting C1 or C2.
>>>>
>>>>This is correct for all modes.
>> 
>> 
>>>>>What is the ramification of starting out with reduced drive, (like 25
>or
>>>>>50 Watts) and adjusting C1 and C2 until maximum output is achieved?
>>>>
>>>>Because the tank circuit is designed to operate at only one impedance
>>>>transformation and Q, and it is usually designed at the maximum key-down
>>>>anode voltage available and maximum rated anode current for the tube(s).
>>>>
>>>>For best harmonic attenuation, cleanliness, and efficiency, always use
>>>>method 2 above.
>>>>
>>>>
>>>>(((73)))
>>>>Phil, K5PC
>>>>
>>>>
>>>>
>>>
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>> 
>> 
>> 
>> 
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