[Elecraft] KX3+KXPA100 operation improved when running from a 12-V battery

[Kenneth A Christiansen]

Hi to the group.

I hope the group wasn't thinking my test conditions were my recommendations for running the KX3-KXPA100 station. I purposely set it up under marginal conditions to test the new software and originally to test the old software. The battery is over 4 years old and I may replace it this spring. There were 3 fuses in the circuit and the KX3 was getting it's power from the duel socket on the KXPA100. The old battery was several tenths of a volt lower than my newer battery although it definitely does not have a dead cell. I could solve much of the problem with the original software just by running the KX3 directly off the battery. A new battery would also help. My goal when camping is 6 db over 5 watts which is 20 watts or 10 db over 5 watts which is 50 watts. I ran at 100 watts on my dummy load to make the entire test as tough as possible. I run almost 100% CW when I am camping as even low power RTTY or PSK31 draws much more total currant from the battery then CW in an hour of operating. 

Fargo has two 50 KW broadcast stations in the area so I was not surprised when I tuned in a 5 KW station that was 230 miles from me that I had the interference problem with the 160 position. I was pleased that the NOR position still worked but having said that I can see myself using the 160 position when I camp in the north wood of Minnesota.

Once again I appreciate these two new options and they are meant to be used with reasonable care.

73

Ken W0CZ w0cz at i29.net


Sent from my iPad

> On Jan 14, 2014, at 9:36 PM, Wayne Burdick <n6kr at elecraft.com> wrote:
> 
> Thanks for the report, Ken.
> 
> At lower voltages, especially in voice modes, you should consider dialing back power output to preserve the amplifier's "headroom." For example, if the supply is dipping below 11 V, I back the power down to about 50 W, just to be safe. This is only a 3-dB drop in power but it'll be a little easier on the gear. For higher/lower voltages, adjust accordingly.
> 
> Of course the amp and radio will protect themselves if, due to reduced voltage, you exceed a threshold of current drain, temperature, or other parameters.
> 
> 73,
> Wayne
> N6KR
> 
> 
>> On Jan 14, 2014, at 6:11 PM, Kenneth A Christiansen <w0cz at i29.net> wrote:
>> 
>> I brought up my old deep discharge battery and am extremely please with the way it now works with the KX3 and the KXPA100. The KX3 was going down to 10.7 volts at 100 watts with about .9 volts of cable voltage loss. My digital meter was going down to 11.6 volts at the battery…
> 
> 
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