[Drake] Drake Power Output

[Glen Zook]

Are you reading the wattmeter when talking?  If so, you should NOT show much more than between 20% and 25% of the power that you get when tuning with CW.  That is because the vast majority of wattmeters available to amateur radio operators are NOT a true peak reading wattmeter.  Frankly, the meter movement cannot follow the peaks of the human voice.  If you are showing much more than this you are over-driving the final amplifier tubes and you will "buckshot", "splatter", and so forth.  Although the meter movement cannot "follow" the peaks of the human voice you are going to be putting out full peak power when the wattmeter shows an average between 20% and 25%.

You can hook up an oscilloscope (which can follow the peaks of the human voice) and see the relationship of the meter reading to the actual peak output.  Your mfj wattmeter is not a true peak reading wattmeter even though it says it is.  A peak reading wattmeter is going to have some electronic circuitry involved and that requires a power supply of some type (other than that required to "run" a pilot lamp).

Glen, K9STH

Website:  http://k9sth.com


--- On Mon, 12/14/09, David Walker <vk2na at bigpond.com> wrote:

Say on 20m I can tune to just over 200w but on SSB I struggle to get more than 60 or 80 watts PEP.  The ALC is active and it starts indicating on the S meter at around 50w PEP. 

My PEP meter is just the MFJ-989C tuner and I'm using the built in dummy load.

Well it sounds like I definitely have a problem. I get nowhere near the PEP power output on 15 and 10m as you guys are suggesting. Personally i suspect it's probably a combo of ALC and soft tubes. 
 
Also the power supply does get a bit warm after some use.  It does not get as warm as it used to with the old caps.  I replaced those after I noticed a hum on my CW tone.  After replacing the caps the hum has gone.