On Sat, 23 Feb 2019 15:21:49 -0500, wrote:

SNIP
John-

I have a Radio Shack HTX-10 transceiver with that problem. When
disconnected from any power source, memory contents were maintained by
the charge on a 220 Microfarad capacitor. Over a month, memory contents
were lost due to leakage.

I installed a 3.6 Volt Lithium battery, isolated by a 1N4004 diode,
across the capacitor. This approach may work for you if the operating
memory voltage is higher than 3.6 Volts.

Last time I checked, memory contents were still good after ten years!

Fred

Hi Fred and others,

I forgot to mention that I was unable to identify the "unique capacitor"
by visual examination of the circuit board. I do not see any "out of the
ordinary" capacitors.

John
They are usually .47F to 1F and are normally short and squat.