M802 crystal heater

[a64pilot]

It’s my understanding the 802 has a heated crystal, while I assume this power draw is slight, but what is the life limit of the heater?
I ask as I was powering my 802 thru a CB and turning it off when in the off season, but now I have it connected to the battery bank directly. So it would be powered permanently.
Is this OK, or do I need to disconnect it during long periods when it won’t be used cause the heater only lasts so long, or does the heater last for decades?

[abarrow]

I doubt seriously that the crystal heater is active when the radio is turned off. One would have to look at the radio schematic to be absolutely sure, but it's highly unlikely. One thing you might do is just watch your current draw and then disconnect the power connector from the back of the radio and see if it drops.


Crystal heaters are there to prevent the radio from drifting in frequency when it is running. There's no real need to have them on when the radio is inactive.

[a64pilot]

Radio off there is a spark when you connect power.
Now that may be a cap charging I don’t know

[Jim Cate]

Don't know about the 802, but in my Icom746 ham rig with optional crystal oven, it is shut off when the power switch is turned off. One can observe this by listening to a signal immediately upon power up... it will drift a few cycles in the first ten seconds or so, and then lock in. And I'd guess the power level is < 1 watt, so virtually undetectable in use.

Jim

[a64pilot]

Found this in the manual

[Wotname]

The M802 does draw power paper when turned off, about 100 mA IIRC. I had always assumed it was for the oven and a64pilot's SM reference above confirms it.

I wired mine directly to the battery via it's own circuit breaker switch so I could remove power completely if/when required.

How long does the heater element last - dunno but I guess a very ling time decades but not centuries.

In the distant past (i.e. decades ago) I have very occasionally replaced heaters in other older transmitters but whether that experience is relevant to the M802 or not is unknown to me.