[time-nuts] HP-105B Battery Replacement?

Brooke Clarke brooke at pacific.net
Wed Sep 14 19:45:32 EDT 2016

Hi Jeremy:

It's a very bad idea to put any battery with acid in an enclosure that has electronics since if it vents the acid will 
etch the PCBs.
Guess how I learned this.  I got a great price on a Gibbs Frequency Standard because the oven no longer worked.

Modern Ni-Cad batteries have much more capacity than older ones and no longer have a memory effect.  They are also very 
easy to charge, so why not just replace the old cells?

Have Fun,

Brooke Clarke, N6GCE
The lesser of evils is still evil.

-------- Original Message --------
> I recently acquired a nice HP-105B, serial prefix 1240A, and like Perry Sandeen (posted here 10 May 2016) was 
> pleasantly surprised to find a 10811-type oscillator inside in place of the old blue oven. Well, the oscillator isn't 
> actually labelled "10811" but has a label "Serial No. 3010A62646 / Hewlett Packard / Made in U.S.A. / R11 147K." So, 
> this is essentially the same oscillator as Perry found in his 105B.
> The oscillator works well although the meter reading for the 5 MHz output is low, about 30 instead of the expected 80 
> (per the 105B manual for the 1240A series). The measured output is also low, about 1 Volt where 1.5 Volt is the 
> expected minimum. Might this be due to the change from the old 105 crystal oven to the 10811?
> What is the received wisdom on replacement of the previously-removed factory Ni-Cad pack? There are many small 12 Volt 
> batteries available, two of which would easily fit into the space available and some of which might not even catch 
> fire! Other options are an external battery+charger or even a UPS on the AC line. Opinions?
> Jeremy / N6WFO
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