[ARC5] Bucking transformer configurations.

[Geoff]

I dont know of any LV transformers that have an insulation issue, it doesnt 
matter which side of the primary the secondary is wound on.

 The same holds true when replacing a tube rectifier with SS diodes and 
using the rectifier filament winding to buck.
In a few cases of where the original 5V winding insulation was insufficient 
from day one as in the Hallicrafters HT-32 and 37's the only choice is to go 
SS and leave the 5R4 winding float.


----- Original Message ----- 
From: "Bill Cromwell" <wrcromwell at gmail.com>
To: "ARC-5MailList" <arc5 at mailman.qth.net>
Sent: Monday, December 10, 2012 8:03 AM
Subject: Re: [ARC5] Bucking transformer configurations.


> On Mon, 2012-12-10 at 20:11 +1100, Brian Clarke wrote:
>> Both diagrams assume the insulation of the secondary from the transformer
>> core is OK. In older transformers, that may not be the case. So, if you 
>> use
>> an older transformer, connect the secondary nearest neutral.
>>
>> 73 de Brian, VK2GCE.
>
> In my own case the older transformer is going to be the protected load
> and one of the newer transformers is likely going to be in the buck
> position. Insulation breakdown could be a problem but I think that's not
> very likely (in my applications) even with an older transformer. In any
> event - that's what fuses are for. You DO use those don't you? I'm
> pretty sure they have saved my hardware, my home, and possibly my life
> several times.
>
> John Forster made a usable diagram and it is exactly the picture I got
> from the description by John  WA4WDL. Somebody else referred to the two
> windings (bucking transformer) being in series aiding but my
> understanding is that it's series opposing. The distinction, at least in
> my easily confused mind, is not trivial. I often struggle to keep terms
> and what they describe straight so I may have it wrong. There is also a
> link to a PDF file and I am going to grab a copy of that. When I go on a
> trip I have paper maps, a printout from google maps, and a GPS device
> telling me when to turn left. It never hurts to compare what you see on
> the road (chassis) in front of you with the "maps" no matter you have
> been down the road before. I've used a bucking transformer a couple of
> times before. Not recently.
>
> 73,
>
> Bill  KU8H
>
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