[Elecraft] Boost power supplies for RF amps

[Jack Brindle]

Bill;

To be fair, we have had one instance of the problem, and that station was running the battery critically low. In fact the battery failed at that voltage (something like 10 volts) and had to be permanently removed from service. Perhaps the answer is to take the battery manufacturer’s advice and not to run the batteries below 11.5 volts. I believe the K3 has a low-voltage alarm that can be applied to the problem so that it gives a warning at the critical voltage and won’t continue until the power is corrected.

In general, we have found the K3 to be an excellent performer when running off battery at 12 to 13.8 volts, whether charging or not. Anyone wishing to hear us, just listed for K6EI in Field Day. And for those who wonder, having great antennas 500 or so feet above San Francisco Bay gives us great signals, even at 5 watts.

- Jack, W6FB


> On Feb 20, 2017, at 4:57 PM, Bill Frantz <frantz at pwpconsult.com> wrote:
> 
> I'm trying to reconcile this advice with our experience running QRP field day. We frequently have two or 3 K3s on a single band (CW, SSB, Digital/GOTA). We use batteries and solar cells since our site does not permit generators. When the radios are being fed from a charged battery or a battery being charged from the solar cells, we don't have a significant problem with interference between stations. (Antenna placement helps a lot too.) When the voltage drops, the complaints increase.
> 
> Of course, our 5 watts is quite a bit below the full power of the low power RF amp in the K3.
> 
> 73 Bill AE6JV
> 
> On 2/21/17 at 4:05 PM, k9yeq at live.com (Bill Johnson) wrote:
> 
>> Reducing the power by 25% will improve IMD performance at lower voltages, yet that power difference is virtually impossible to detect on the H.F.
>> bands.
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