[Elecraft] A Matter of Power...

[Ron D'Eau Claire]

K2 S/N 1289 made an SSB contact last night and another one this morning.
For a dedicated "brass pounder", that is something truly notable. 

Last night was an hour-long BFO frequency-tweaking session with Lou,
W7DZN, getting the SSB filters set up for the optimum sound. Today was
simple ragchew with club station K6YVM aboard the WWII Cargo Ship, the
Red Oak Victory. He said that my signal was fine but a little weak. I
noticed that I had the power set at 10 watts, not 100 watts. 

It also brought up the issue of power. R-F power. How much is enough? 

I can't answer that. But talking about it brought up some facts about
power on the ham bands that some of the newer ops contemplating QRP vs.
QRO might enjoy and find useful. 

Back in the late 1950's, I "graduated" from my one-tube
crystal-controlled cw rig to a Viking Ranger. The Ranger was one of the
"standards" on the ham bands, much like many of the Yaesu's and Icom's
today (except that I built it, of course!). It ran 65 watts AM and 75
watts CW. I played around quite a bit on the "phone" bands then, and
never had to apologize for running 65 watts. That was a very typical
power for a phone station in those days. But 65 watts in the Ranger was
quite a different thing from setting 65 watts on the power control of a
K2/100. 

The Ranger's power was specified as "d-c input to the final amplifier"
as all Ham rigs were rated in those days. That meant that the final tube
consumed 65 watts, not put 65 watts out. An overall efficiency in the
amplifier and output circuit of 60% was considered good, so that 65
watts d-c input was actually something like 40 watts r-f output. 

And it was double-sideband "AM Phone". That means that 2/3 of that 40
watts, a full 26 watts, was the unmodulated carrier that did nothing to
help the audio get through. That left 14 watts of sideband power. 

But wait, that 14 watts is in TWO redundant sidebands. Since two
sidebands take up twice the spectrum space of one sideband, there is NO
signal-to-noise improvement to be had by transmitting them. One sideband
passing through a receiver with just enough i-f bandpass to handle it
will sound just as loud. 

So my 65-watt Ranger was equivalent to a K2 running 7 watts PEP SSB. And
in the 1950's and '60's it was considered a pretty typical rig on the
bands. I certainly had a lot of enjoyable QSO's with it. 

My point is that if you choose to run a QRP K2, you are in good company
-- good, historic company among a lot of ops who won DXCC and set a lot
of records over the years. Indeed, work the numbers and you will see
that the ops running 100 watts PEP today are putting out almost the same
"talk power" as the "big guns" of  my youth who were running close to a
full kilowatt, the legal limit back then. With smaller and more
efficient rigs, running really HIGH power has become "normal". No wonder
so many Hams can make DXCC is a matter of days. Forty years ago the
smallest kilowatt rig was the size of a desk. Indeed, E.F. Johnson made
one that WAS an operating desk. And one needed a 220 volt service in the
ham shack to light it up. 

This musing came up when I worked the station aboard the USS Red Oak
Victory because I "turned up the wick" to 100 watts PEP. I've NEVER run
so much "talk power" in my 50 years on the Ham bands. 

No, I don't own the KPA100. It was loaned to me to "play with" by none
other than the "toroidguy" himself, Mychael, AA3WF. And let me tell you,
he builds rigs as well as he winds those toroids...  

Ron AC7AC
K2 # 1289