Power consumption and HF operations

Feb 17, 2006
5,102
Lancer 27PS MCB Camp Pendleton KF6BL
Now that I have my radio back, but not on the boat yet (if ever :cry:), I have decided to set a metric for power output vs power consumed.

I have three fixed levels of power on my radio; 10, 50, and 100 watts. Here is what I have measured using an Extech True RMS current clamp meter.

Kenwood TS-50S, 20 amp DC power supply, CW keydown (current draw rounded to nearest A/H)

RX - 1 A/H
TX 10W - 6 A/H
TX 50W - 13 A/H
TX 100W - 18 A/H

In SSB mode I noticed that at key down and voice peaks, the current was about the same as the preceeding value, i.e. 100W showed about the same at peaks as the 50W CW keydown and fluctuated.

I did not test for voltage drop. My PS is regulated so I doubt that would be a valid test. I will have to use a 12V battery to test for voltage drop.
 
Sep 25, 2008
6,314
Alden 50 Sarasota, Florida
Have you considered the use of one of the newer instruments to measure rms current draw?

I've seen reviews of a few and advertising in QST but never paid much attention.
 
Feb 17, 2006
5,102
Lancer 27PS MCB Camp Pendleton KF6BL
You mean for monitoring SSB current draw? That is a thought but I haven't looked into it. I guess if the meter averaged out the current it would be close. I think Maine Sail did a piece on something for monitoring battery current draw. Wonder if that would also work if connected between the rig and its source of DC power.
 
Sep 25, 2008
6,314
Alden 50 Sarasota, Florida
I was referring to mean current draw or total rather than instantaneous. I was assuming you were shooting for some way to monitor battery drain from the radio.
 
Feb 17, 2006
5,102
Lancer 27PS MCB Camp Pendleton KF6BL
No, yeah, huh!?! LOL Yeah, that is correct. I personally would put the radio on separate battery bank (golf cart maybe) so as not to over draw on the house bank. But I agree on the monitoring of SSB current draw.
 
Oct 6, 2009
97
Custom Bluehull Kennesaw, Ga.
Well if you have a separate battery for it already, just put a watt meter in line and record your findings and do it the old fashion way, Trail and Error. Keep us posted on your findings.
 
Feb 17, 2006
5,102
Lancer 27PS MCB Camp Pendleton KF6BL
I have heard of a guy using a 7A/H SLA battery. I am sure it will work if one is using low power all the time (re: QRP). Would be interesting to try different battery types.

As far as testing it, don't wait too long. LOL I would have to bring a battery home. I have a motorcycle battery I can try. Hmmm...
 
Oct 6, 2009
97
Custom Bluehull Kennesaw, Ga.
I haven't really done any testing, but I have used an extra deep cycle battery and worked a FT-857 around 4 or 5hrs with no problem, not even sure how much power I was putting out, but it work good enough for me.