[GreenKeys] Loop supplies/ST-6?

[Nick England]

Do I understand you are using your ST-6 in series with your CV-2460 and TTY
machines?
Then your problem getting 60ma isn’t the ST-6 current capability but having
enough voltage to overcome all the serial loop resistance. That may be way
too much voltage. See #2 below

1) Standard practice is to have multiple loops driven by a single loop
supply. Each loop has only one TU or CV with jacks/patch cords to insert a
TTY into the desired loop. The 1000ma loop supply is so you can supply a
dozen parallel loops. No one runs a single 1000ma loop!

2) IIRC, the CV-2460 has a low current mark-hold where it inserts an
additional 2K resistor into the loop. That’s sufficient to hold the
selector magnets in, but it’ll obviously cause a low current issue if you
are using the ST-6.

I highly recommend configuration #1. Don’t modify your ST-6, just make it’s
loop separate from all the other loops driven by the Navy supply. Navy TTY
patch panels include jumper posts so that any of the 6 (or 24) loops can be
powered either by that loop’s TU or by the large common supply.

Works good, works fine, paint it gray, lasts a long time.

Nick England K4NYW
www.navy-radio.com


On Mon, Apr 8, 2024 at 7:45 PM W2HX <w2hx at w2hx.com> wrote:

> Hi all
>
>
>
> For many years, I’ve used my ST-6 as my TU with its built-in loop supply.
> These days as I am using a different TU for the 850 shift stuff. I still
> use my ST-6 but in STDBY (mark hold) mode just to have it supply loop
> current to the equipment as my CV-2460 expects and external loop supply
> (but not use the ST-6 as a TU for 850 Hz).
>
>
>
> The number of machines on the loop has grown and therefore has been
> reducing the current that is able to be supplied by the ST-6 as I don’t
> think it was meant to handle more than a few devices. I have maxed out the
> rheostat in the ST6 (or minimized it as is the case). So I acquired a navy
> loop supply, designation PP-3495A (attached) that can supply 120VDC at a
> full 1A output.
>
>
>
> I was wondering if anyone has modified an ST-6 to disable its internal
> loop supply and allow it to be used with an external supply? This way I can
> use one loop supply regardless of which TU/CV I am using to drive the loop
> (of course, the unused TU/CV would have to be in bypass/standby/mark-hold
> mode).
>
>
>
> Thanks
>
>
>
>
>
> 73 Eugene W2HX
> My Youtube Channel: https://www.youtube.com/@w2hx/videos
>
>
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