[time-nuts] HP 5065 Rb update

[Bob kb8tq]

Hi

What we are dealing with here is a transistor circuit that 
does indeed need the low value pot. It also needs to beL
*very* stable. Lots of details on just how stable at:

HP5065A <http://phk.freebsd.dk/hacks/HP5065A/>

Bob

> On Dec 5, 2020, at 4:37 PM, ed breya <eb at telight.com> wrote:
> 
> Paul, if the pot is 1 k, set up as a DC divider from a low-Z reference voltage, and only lightly loaded by an amplifier circuit, you could try upping it to a 2 k or 5 k, possibly 10 k, and get an immediate resolution/set-ability boost, with little effect on the rest, and no other part changes (except for whatever you need to get that nominal C-field current in the right range - a separate issue).
> 
> An easy way to assess the pot capability in-circuit, is to put a high resolution (5 or 6 digits) DVM on the wiper or amplifier output, and just pick some values of voltage, and see how closely you can tweak it to any particular value. You can also observe the discreteness of the steps, the lash, and maybe some interpolation ripple (non-monotonic behavior), by very slowly rotating it while watching the DVM values. This will of course also show if there are any bad spots on the pot, due to wear, corrosion, dirt, deteriorated grease, etc.
> 
> Ed
> 
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