[ARC5] Use of a Variac

[MICHAEL BITTNER]

Tim, the ZM-11B/U is a Bureau of Ships item. Good old Navy grey with rugged case and carry handle.  Most likely used in all places you listed, except R&D labs, along with similarly built items such as TV-7 and OS-8U.  Never fails every time I turn it on after decades of intermittent use although the 6E5 eye tube is starting to dim a little.  Mine came from a surplus store in San Diego and was built by Compudyne Corp.  Mike, W6MAB

> On April 24, 2020 at 2:19 PM Tim <timsamm at gmail.com> wrote:
> 
>     The ZM-11 looks to be a capable instrument - Is it "military"?  If so, I wonder where they were actually used.  Line Maintenence?  Organizational repair? Depot repair?  Depot overhaul?  Manufacturer component parts QA?  DOD R&D Labs?  Lot of capability, looks cool!
> 
>     Tim
>     N6CC
> 
>     On Fri, Apr 24, 2020 at 10:56 AM David Stinson < arc5 at ix.netcom.com mailto:arc5 at ix.netcom.com > wrote:
> 
>         > > 
> >         With the ZM-11, you set the internal DC supply to the operating voltage for the cap, i.e. 450VDC.  The DC supply is developed by a low-current RF flyback system which can deliver several mA without any trouble and will "live" if your cap is shorted. You don't usually have to "baby-sit" the process. Connect the cap.  The ZM will current-limit down to a lower voltage and start reforming.  Once the voltmeter makes it to operating Voltage (minus "normal" leakage, usually less than 1 mA) you're good to go.
> >         I've had a few that went ahead and shorted and many which can't "make the cut," but most are recoverable.  Don't remember ever having trouble with a cap after being acceptably reformed.
> >         That said, when more desirable and available, I will install new caps.
> >         73 Dave S.
> > 
> >         On 4/23/2020 6:25 PM, Mike Feher wrote:
> > 
> >             > > > 
> > >             Most of the reforming I did, I used my time. I would start at a low voltage at a comfortable current like about 5 ma and then wait and do something else. Come back to it and if the current went down I would increase the voltage for the same current, and so on. I kept it up till I reached rated voltage
> > > 
> > > 
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