[TenTec] Paragon 2 Memory Battery Back-up

[Dr. Gerald N. Johnson]

It would make more sense to find an original Motorola data sheet on the 
part. It might well be that if the circuit pulled reset to ground (as it 
would if the diode was in the right place) that the chip current would 
be very low. Anyway, it would be little trouble these days to have 1 
amperhour of NiCaD at 6 volts (dropping to 4.8 under time and load) 
charged at maybe 50 milliamps when the rig was powered. Many a 
computer's CMOS memory has been powered that way for decades.

I did find a "replacement" chip data sheet but it didn't mention memory 
backup. I might look more in my databooks, but a big bunch of them have 
been packed and moved and not yet unpacked and probably won't be 
unpacked for a while.

Seems to me I saw mention on this forum that there two versions, some 
with external battery backup all ready in place. Maybe that was another 
TT radio.

73, Jerry, K0CQ

On 5/30/2010 4:00 PM, LEE BAHR wrote:
> Jerry:
>
> Thanks for the input. This makes sense. My concern is for a Paragon 2. I
> don't have one yet but plan to buy one if/when I can find one to my
> liking. Maybe there is someone on here who actually did this. I would
> suspect it has been done many times since the manual says the "cell"
> within the microprocessor chip will maintain memory and work for around
> 10 years. These cells must all be dead bye now. I have never had a radio
> without a small outboard battery which could be slipped in and out of
> it's holder. For those radios I routinely change them after a few years
> of service. That is easy and fast. This idea of having an internal
> "cell" good for 10 years being built into a microprocessor mystifies me.
> I can't imagine why this would be done. I have not heard of anyone being
> annoyed by this, so there must be some remedy for the problem.
>
> Lee, w0vt
> Houston, Tx
>
>
>
>>
>> Without having done it, I suppose one would cut the 5.6 volt power to
>> the processor chip pin 40, insert a schottky diode for minimal voltage
>> drop, then hook up a 6 volt chargeable battery (charged from the
>> unregulated 13 volts) through a plain silicon diode to that same pin 40.
>> 4 NiCad cells should hold the micro for a long time, might not need to
>> be chargeable, just a couple 3 volt Li Cells, like 2032 in series to
>> make 6 volts. When power was on the battery diode would be reverse
>> biased, when power was off the schottky diode would be reverse biased
>> and the battery would keep the processor supplied with power. Likely it
>> takes a lot more power to hold up the processor than the processor's
>> memory alone. I can't tell from the schematic what the processor number
>> is, it shows the same MC146803EP2 part on a 40 pin and a 16 pin package.
>> What is it really (Paragon II)?
>>
>> 73, Jerry, K0CQ
>>
>
>