[time-nuts] Re: Z3801A questions

[Mahlon Haunschild]

Well, as expected, when connected across my 48VDC infinite current source (e.g. golf car battery) the Z3801A booted right up.  

Now all I need is a 48VDC 5A unregulated power supply.  Decades ago, these things were a dime a dozen.  Now they cost hundreds of dollars.

Or maybe a suitable step-start or ICR between the Vicor SMPS and the Z3801A.  After all, the Z3801A only draws roughly 500 mA, steady-state, while the Vicor can source 2.9A.  Plenty of room for that sort of thing.

Thanks for your support.

Best regards

Mahlon - N4ZK

> On May 22, 2023, at 6:26 PM, Mahlon Haunschild <k4oq.radio at gmail.com> wrote:
> 
> Ed,
> 
> I think my 48V golf car battery bank is stiff enough for this :)
> 
> Seriously, that is what I always intended to try first.  Fed through a suitable fuse/circuit breaker, of course.  Will give it a go and report back later.
> 
> Best regards
> 
> Mahlon -N4ZK
> 
>> On May 22, 2023, at 2:19 PM, ed breya via time-nuts <time-nuts at lists.febo.com> wrote:
>> 
>> Before doing a bunch of mods to the Z3801A PS, it would be wise to try running it from a linear supply with enough V and A to launch. SMPSs usually have a hard time with load startup surges. In PS experimenting on my 24V unit, I found that SMPS units of seemingly adequate size - even two paralleled - could not fire it up from cold. Neither could a linear one, unless rated for much higher output current - it would fold-back and stall.
>> 
>> The bottom line is that you need substantially more than nameplate current to get these puppies up and running. They were built to run from telecom battery bus supplies, which can handle those critical few
>> seconds at startup.
>> 
>> An old-school unregulated transformer/rectifier/capacitor supply is the closest match. This kind of setup can be sized (VA-wise) close to the normal running power needed, but is forgiving enough to handle the startup surge - use a slow fuse sized about right for steady-state VA.
>> 
>> Ed
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