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@texascellnet.com>
>To: "'Steven Cook'" <sccook1@cox.net>; <Amps@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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