What voltage do you think the KX3 can tolerate?

During my activation of DM/BW-078, the setup went smoothly until I switched on the KX3. Then I saw a message on the dispaly, saying something like: 'above 15 V‘. The words took a second to sink in, then I immediately hit the buttons and switched the KX3 off.
By mistake, I connected a fully charged 4S Li-Ion battery to the KX3. The voltage reducer, which is mandatory when using this kind of battery, was missing. I knew it had to happen one day! The KX3 supply voltage was approx. 16.3 volts. :astonished:

When my blood pressure returned to normal, I plugged in the voltage reducer and turned the KX3 back on. Fortunately, there was no damage whatsoever. Thanks, Elecraft for the rugged design!

This mistake was possible because all my DC connectors are of the same type.
New task: change the 4S battery connector to a different type.

Answer to above question: The KX3 can tolerate up to 16.3 volts but I won’t try it again :sweat:

From https://ftp.elecraft.com/KX3/Manuals%20Downloads/E740163%20KX3%20Owner’s%20man%20Rev%20C5.pdf

Supply Voltage and Current:
8 V min, 15 V max. 1 to 2 A typical in transmit; 150 mA minimum receive, typical (backlight off, preamp off, no signal)

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I believe all the modern radios use a voltage regulator chip (for non RF power supply) that can handle 16VDC. Most radios I know state 13.8VDC ± 15% (which is 15.9 VDC). This confirms what the regulator chip can handle. Furthermore, from looking at a few datasheets most RF power MOSFETs and other such devices used in the RF amp sections can handle 20VDC (from what I have seen).

I do the same as you, using a fully charged 4C LiPO and a diode bridge to drop it from 16.8VDC to 15.4VDC. I once forgot my diode bridge and pumped 16.8VDC into my FTM-100DR. No problems. But I won’t do it again!

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