Most power ever on HF activation?

Hi Andrew,
Yes, if I carry my 100W rig I have to double the battery also. When I got my 100W IC706-2G in 1999, I tested it for current consumption. Later I did a weight reducing exercise for SOTA. As you will know, like most 100W rigs, the 706 is rated at 100W output for 13.8V / 20A input.

Using a fully charged SLAB (12.6VOC - 11.1V key down at rig input set to full RF out - maybe about 70 to 80W considering the voltage input) I got the following results which are approximate due to lack of an absorption Wattmeter that would do the power:

Rig on setting H: 16.3 Amps input (about 70 to 80W?) (Highest power setting)
Rig on setting 7: 13 Amps input (about 50W)
Rig on setting 5: 10.3 Amps input (about 23W)
Rig on setting 3: 7.8 Amps input (about 10W)
Rig on setting 2: 6.6 Amps input (about 3W)
Rig on setting 1: 5.6 Amps input (about 2W)
Rig on setting L: 5.4 Amps input (less than 2W) (Lowest power setting)

I used the rig for SOTA for a number of years, sometimes multiple summits with over 5000ft ascent and SLAB’s. I knew that reducing power below about 40W was futile and would cost me double. That is, efficiency becomes ridiculously poor but not only that QSO rate would drop with RST repeats more frequently required.

The lightened rig plus short coax leads, power leads and circuit breaker weighs 2.6kg.
Nowadays, it’s rare I need this rig for SOTA unless I’m trying to do 160m in daylight and/or maybe a VHF band as well, when to quote Dave’s words, every Watt counts.

Nowadays I use an FT817ND coupled to a 50W amp, the MX-P50M. This combi’ weights about 2kg inc leads etc. and needs 7 or 8 amps to run a more than useful power output of 40 to 50W. Receive current on the 817 is far lower than the 1.1 Amp required for the big rig. Batteries seem to last far longer than you’d expect and I only need one 5Ah Li-Po as against two in parallel for any useful life with the IC706. I have not discounted the use of the 706 however. It is still needed and taken to summits in certain circumstances, like GD/GD-003 recently.

Conclusion: You are dead right! Standing current on a big PA is always sucking your battery no matter how much you try to save.

PS: That doesn’t mean I don’t agree with how Dave G0EVV operates using his FT857D; he is aware of the above circumstances, is prepared to carry the weight required and is more than capable. Keeps you fit anyway! According to my SOTA chaser friend across the road Roy G4SSH, the chaser experience is almost always very good when Dave is operating.

Thanks for posting.
73, John

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I’m glad that the summer silly season (SSS) is coming to an end…:wink::wink:

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 80 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

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I think we have a winner! I can’t see anyone beating 1 kW anytime soon.

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That’s just setting the bar for the challenge though Richard!

Oh hey thats me :smiley:

I just did the talking, @2E0YYY and @G4OIG did the hard work :stuck_out_tongue:
But have the video to prove it.

I do have a little giggle when NA ops say things like " dont bother with QRP", sun spot this and charts that… know what guarantees no contacts? Not bloody trying!

W

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