On Tue,12/29/2015 7:57 AM, John Macrae wrote:
I run /P on a 35aH lead acid battery. Whilst there is a noticeable voltage drop, I have worked dx till the battery voltage falls well below 11v without any noticeable effects on signal quality (I asked)!
It is well known that IMD (splatter, clicks) with a K3 is least with higher DC supply voltage, and increases as the supply voltage is lower. By 11V, it's increased a lot.
IMD is also reduced when the K3 operates at lower power. This is helpful when you're driving a power amp. The KPA500 needs about 25-30W for full power, my big 1.5kW tube amps need about 50W.
There is a menu setting for the DC voltage below which the K3 will not transmit. Check the manual.
I have also run from a battery in the shack with a charger connected. No problem.
I currently run from two big 6V golf cart batteries that are float-charged by a regulated DC supply. With the charger connected, I get about 13.4V on TX. Without the charger, the voltage falls below 11.5 V when the batteries are getting low. Because I'm usually driving an amp, I have my K3s set to cut off at 11V.
Clearly the larger the battery, the less problems you will have.
Yes, but the battery chemistry also matters. The "normal" operating voltage of LiFePO4 batteries is at least a volt higher than lead-acid, and the discharge curve is flatter. The problem is that LiFePO4 is currently a lot more expensive, and the chemistry requires a special charger. Prices are gradually dropping, and eventually that's likely where I'll end up.
73, Jim K9YC ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html Message delivered to [email protected]
