[GreenKeys] Loop supplies/ST-6?

Tue Apr 9 08:15:23 EDT 2024

I'm blessed to have versions of the mailer and OS that don't have the 
auto correct.  I can take credit/blame for any and all of the mistakes.

Now understand the failure rate of many of my past projects.  No gray 
paint in the BOM.

On 4/9/2024 6:52 AM, Nick England wrote:
> Update. I know the difference between its and it’s but autocorrect 
> doesn’t.
>
> Nick England K4NYW
> www.navy-radio.com <http://www.navy-radio.com>
>
>
> On Tue, Apr 9, 2024 at 7:49 AM Nick England <navy.radio at gmail.com 
> <mailto:navy.radio at gmail.com>> wrote:
>
>     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 <http://www.navy-radio.com>
>
>
>     On Mon, Apr 8, 2024 at 7:45 PM W2HX <w2hx at w2hx.com
>     <mailto: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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>>>> Jordan Spencer Cunningham's GreenKeys Search Tool: https://teletype.net/gksearch
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The above comments or recommendations are SWAG. Use at your own risk.

John, W9DDD