[Amps] Why does power output increase?

[Victor Rosenthal 4X6GP]

I read his article. He uses an RF filter. I might try that.
My meter is a "good" one, a Fluke. But of course I've never sent it out 
for calibration.

73,
Victor, 4X6GP
Rehovot, Israel
CWops #5
Formerly K2VCO
https://www.qsl.net/k2vco/
On 05/06/2022 16:12, Jim W7RY wrote:
> One also needs to make sure they are measuring the filament voltage with 
> a true RMS voltmeter.
> 
> 
> Most cheap meters wont do that.
> 
> 
> 
> Did you take a look at W8JI's site for measuring filament voltage. He 
> does is successfully with drive power.
> 
> 
> 73, Jim W7RY
> 
> 
> 
> On 6/5/2022 6:04 AM, Victor Rosenthal 4X6GP wrote:
>> I did measure the voltage at the tube pins. I haven't measured it 
>> while transmitting, because the RF drives my meter crazy. I assume the 
>> voltage drops a bit. Unfortunately I no longer have my trusty analog 
>> voltmeter. I wish I did.
>>
>> I'll measure the line voltage. But the only thing I can think of that 
>> would cause that to increase after long transmissions would be if the 
>> breaker on the line heated up and lost resistance. I have never heard 
>> of that!
>>
>> 73,
>> Victor, 4X6GP
>> Rehovot, Israel
>> CWops #5
>> Formerly K2VCO
>> https://www.qsl.net/k2vco/
>> On 05/06/2022 6:19, Jim W7RY wrote:
>>> *I'm curious Vic...*
>>>
>>> *See below"*
>>>
>>> On 6/4/2022 4:35 AM, Victor Rosenthal 4X6GP wrote:
>>>> This isn't a problem, just a phenomenon that I would like to 
>>>> understand.
>>>> I have a TL922. Mods include directly grounded grids. I also 
>>>> measured the filament voltage with my Fluke true RMS meter and put a 
>>>> small resistor in the primary of the filament transformer to provide 
>>>> exactly 5.0v in standby.
>>> *Where did you measure this voltage. Best is to wrap a small wire 
>>> around the tube pins, (all 3 of them) and measure the voltage at each 
>>> tube.*
>>>>
>>>> It has been running with the same genuine Eimac 3-500Zs in it for 
>>>> about 6 years.
>>>>
>>>> So here is what happens: after a longish CW transmission, the power 
>>>> output INCREASES. On 20m, for example, it may go from 1200 to 1400 
>>>> watts. When it cools, the power drops back.
>>>>
>>>> I've noticed this with several wattmeters. I have observed no change 
>>>> in SWR when this happens (it's 1:1 thanks to a Johnson KW Matchbox).
>>>>
>>>> It happens when the amp is driven with an Elecraft K3 and also a 
>>>> TS890s.
>>>>
>>>> I'm interested in hearing theories about why this might occur.
>>>
>>> *I cant add anything about what your seeing... Other than is the line 
>>> voltage changing?
>>> *
>>>
>>> *73, Jim W7RY*
>>>
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