One KW using the Heathkit KW Kompact with DC supply and Kenwood 430S, powered by a 100 amp hour communications battery for the amp. SSB only. RF feedback required some re-positioning from what is shown in the picture. Battery weighs 60 pounds. Drive-on summit, of course. No need for that much power, but Eric, KU6J, dared me to do it. Once was enough. The usual amp is an HF Packer Amp at 35 watts.
Elliott, K6EL
I’ve heard you with that amp, EL, it sounds great! I had one of those, wish I had kept it.
On another note, I’ve noticed many of the DX activators don’t hear so well, I hear them with
their 5 or 10 watts and little wire antennas, but they don’t hear me until I’m running a KW.
I can call with 100 watts and a 3 element beam and they don’t hear. Then I turn on the amp
and they hear!
73,
K6YK
There’s big kudos for running QRP on a super wanted summit and being able to control the pile-up. It’s also immensely satisfying busting pile-ups using 5-10W SSB. But I don’t care how much power people use as long as their signal is decent and they operate nicely.
When we go contesting we’ve run either 100W or 400W (a kW this May maybe???) into moderate antennas from a site with a reasonable take on 2/70 and a bit less on 23cm. We’d be mortified if someone complained we had a cruddy signal as we can be heard over a large area.
So all that matters if you run big power is that you operate well and the signal is clean. If you meet those requirements, who cares how many photons you squirt into the aether.
That is NOT the case. Your receiver might be 6dB more sensitive than that of the activator in which case you would need 40w.
Big decision that, to get or not to get. Whether its solid state or thermionic, an HF linear amplifier is the most likely piece of equipment to break down.
73 Phil
Similar experience chasing DX summits, though not often, and of course a more common occurrence on SSB.
The chases where I have to resort to using the amp seem to be the ones most appreciated by the activator, probably because they were not hearing many – or any – other DX chasers.
This thread set me thinking. Since the start of this year, I have been concentrating on 10m because of the Challenge. Generally the background noise is very low, and it is possible to find a clear frequency with little or no QRM.
I have been using my FT817 and a small amplifier producing about 40W. More than ever before, I have noticed that a few stations calling me have been either very difficult copy, or too weak to copy at all. This lead me to question the receiver. However -
The spec for the FT817ND quotes 0.25 microvolts for 10dB S/N, and my home station FTDX10 quotes 0.16 microvolts.
Assuming that the FTDX10 is typical of modern SDR receivers in this regard, that gives a small advantage for those who use such equipment - about 4dBm, I think.
The amplifier at 40W gives me a 9dBm advantage over 5W.
So, to match the benefit of my amplifier (9dBm) and their better receiver (4dBm) they would need to run 13dBm above 5W which would be 100W, for me to copy them as well as they are copying me.
(I very rarely use an amplifier on other bands, but having salvaged a small CB amp, repaired it, and added a low pass filter, it seems rude not to use it! I’m sure the novelty will wear off eventually 
This is the theory:
But the real is that a 800 or 1000w make a punch to get better results in most cases.
And the FT-817 also lacks any noise reduction tech, which can be worth even more dB advantage for the SDR
Which leads me to ask myself whether it’s worth building a preamp for 10M ? Maybe with a J310
Rick
You are putting the preamp in the wrong radio, surely? If the chaser already uses 1kw they have plenty of signal strength at the 817 portable. A preamp will make the whole pileup stronger.
73 Andrew VK1DA/VK2DA
