[GreenKeys] TTY loop jack boxes - SET, LPG, MISC

Mon Aug 16 05:03:19 EDT 2021

OK.  More grist, thank you :->.  I found the following diagram in another document last night.  It just seems weird to me.  Can you explain?

I read it to mean that:

1.     SET (via patch cord) brings equipment hard-wired as EQUIP SIDE out to another channel (leaving the original channel uninterrupted).

2.     LOOP (via patch cord) acts like LOOPING but also disconnects equipment hard-wired as EQUIP SIDE.

It seems to me that LOOP is functionally equivalent to LOOPING if a dummy plug is simultaneously inserted into SET.  Is that savings of a dummy plug (and remembering to use it!) the rationale for the LOOP jack?

And then, how is the SB-1210 handier in practice for having two SET jacks?  How might that, for example, apply to my scenario?

From: Nick England [mailto:navy.radio at gmail.com] 
Sent: Sunday, August 15, 2021 8:59 AM
To: Paul Birkel
Cc: Greenkeys
Subject: Re: TTY loop jack boxes - SET, LPG, MISC

Oh yes one more comment about wiring your TD to the SET jack of another channel. That would be fine. Or you could just leave the TD on a MISC jack and jumper the SET connection on that extra channel (assuming it has a loop supply). Then you could plug in whatever equipment you wanted to the LPG jacks of that dummy loop. 

On Sun, Aug 15, 2021 at 8:38 AM Nick England <navy.radio at gmail.com> wrote:

Sounds like you have got it pretty much figured out.

Usually LINE (TB-101) was connected to a keyer or converter and SET to a printer or reperf or TD. 

None of the Navy RATT/RTTY keyers, converters, or TUs had an internal loop supply - so the standard installation was a single loop supply that was used for all six channels. The default shows that. 

IF your TU supplies loop current, then change the strapping to REMOTE for that channel, maintaining polarity. See https://www.navy-radio.com/rtty/patch/1203a-man-05.JPG - you still hook up that TU to TB-101 and TB-102 is still available for SET use.

A keyer or converter would be wired to the LINE terminals on TB-101. If no keyer or converter is used for that channel you could connect a TD, reperf, printer, or just a strap. BUT note that piece of equipment would always be connected to that channel - you could not patch it elsewhere.

Some of the converters had the minus line connected to ground so that would be wired to TB-101/1 for example. Don't try to put one of these converters on a MISC jack and then plug it into a loop - it'll just short out the loop before it gets to the SET.

Printers were often polarity sensitive so the plus lead would go to TIP. 

Patch cords were wired TIP-TIP and SHELL-SHELL - All 60ma loop panels used TS jacks and plugs.The Navy later used TRS for low-level (+/-6v) panels.

I'd agree with John that putting the ROTR on a SET connection might be nicer so that it wouldn't run open. Otherwise put it on a MISC jack and leave it patched into a LPG jack on some channel.

The SB-1210 version is a little more handy in that it has two SET jacks and two LPG jacks (and it is bright CRYPTO red)......

Nick England K4NYW
www.navy-radio.com

On Sun, Aug 15, 2021 at 6:21 AM Paul Birkel <pbirkel at gmail.com> wrote:

So … I’m still not the “sharpest crayon in the box” on this topic.  Let me use the SB-1203/UG as my example (documented online at: https://www.navy-radio.com/rtty/sb1203.htm).  It has six identical circuits (“channels”) – one example diagrammed at:  https://www.navy-radio.com/rtty/patch/1203a-man-07.JPG

Inside the unit there are several sets of terminal strips (see: https://www.navy-radio.com/rtty/patch/1203a-man-01.JPG) establishing pairs of permanent connections corresponding to the TB-* appearing at the bottom of the example schematic diagram.

TB-101 would normally connect to some equipment  (this is, I think, “(LINE LPG)” in the terminal strip diagram) that is _always_ in that particular channel (examples from that terminal strip diagram are “RADIO ADAPTERS, FREQUENCY SHIFT KEYERS, LINE MODULATORS”), and may optionally supply loop-current, correct?

Alternatively TB-101 could be strapped closed under the assumption that there is a SET connected to TB-102 and there is a loop-supply established via TB-104 and the default strapping?

The distinction between TB-101 and TB-102 seems to be whether the SET supplies loop-current or not, correct?

TB-102 (SET jack) would connect to some equipment that is normally in that channel, but can be either:

    (1) removed from that channel by inserting some sort of “dummy” plug (has no internal wiring)? … or

    (2) removed from that channel and connected into some other channel using a patch cord

            that establishes a connection between two plugs where the second plug is then inserted into

            a LPG jack on another channel?

TB-103 (MISC jack) would connect some equipment that is not in any channel, to some channel using a patch cord  to a LPG jack?

(The documentation for this unit is quite good; my comments above attempt to summarize my functional understanding of how it is intended to be employed as an exemplar of what I assume is a pretty standard approach to loop jack boxes.)

Is “patch cord” the correct terminology?  Is it just wired tip-to-tip and ring-to-ring (or shell-to-shell if two-wire)?  Are they normally TRS (shell left unconnected?) or TS?

Now, for a use-case, if my source were a self-powered loop from a Flesher TU-170 (which incorporates a loop supply and 0.125A fuse) it seems to me that I’d:

1.     Strap the SB-1203/UG for REMOTE internally (rather than use the default strapping for a TB-104-connected loop supply).

2.     Connect the TU-170 to TB-101.

3.     Connect a (for example) M15 to TB-102 (SET jack).

4.     Connect a (for example) M14 ROTR to TB-103 (MISC jack).

5.     Connect a (for example) M14 TD to a different TB-103 (some other MISC jack)

6.     Optionally add a loop-cable from MISC to an JPG jack to use the M14 ROTR to generate a paper tape of traffic between the TU-170 and M15.

7.     Optionally add a loop-cable from other-MISC to an JPG jack to use the M14 TD to read a paper tape “into” traffic between the TU-170 and M15.

8.     Optionally add a loop-cable from SET to an JPG jack in some _other_ channel to move the M15 to that other channel (which would need to have at least loop supply established).

Would this be a reasonable approach?  Would it be a _good_ approach if these were the four items to be co-employed in this use-case :->?

Would it, in fact, be better to treat the M14 TD as a SET in a different (powered) loop in which case I could then either:

A.    cross-connect the M15 there, or

B.    cross-connect the M14 ROTR there, or

C.    cross-connect the M14 TD into the TU-170 loop?

This seems like a more flexible approach assuming that there is available a separate loop supply for the second loop.

Am I thinking about all of this “right”?  Inquiring minds want to know!

Thank you,

paul

(A long message, but I’ve not gleaned enough specificity from GK traffic archives.  Hopefully by being pedantic here … we’ll avoid more “dull crayons” in the future :->)

From: greenkeys-bounces at mailman.qth.net [mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of Nick England
Sent: Sunday, August 08, 2021 3:33 PM
To: Greenkeys
Subject: [GreenKeys] Fwd: TTY loop jack boxes - eBay

Argghh - I forgot to include the link to my page with schematic and explanation

https://www.navy-radio.com/rtty-patch.htm

In the schematic for this type of box, you will see that the LPG jacks are shorted when nothing is plugged in. When nothing is plugged into the SET jack, the associated equipment is in the loop. When you plug a cable into into the SET jack, the equipment is taken out of the loop onto the cable and the loop is shorted. This is so you can plug the equipment normally in Loop 1 into Loop 2 for example and vice-versa (jumper SET-1 to LPG-2 and jumper SET-2 to LPG-1).

"NOTE: Anyone patching or unpatching circuits from a TTY panel must be sure to pull the plug from the looping jack (LPG) before removing the other plug from the SET (machine) jack. Pulling the SET jack first interrupts all TTY message traffic on that channel. IT ALSO PRODUCES A DANGEROUS DC VOLTAGE ON THE EXPOSED PLUG!" 

Nick England K4NYW
www.navy-radio.com

-- 

Nick England K4NYW
www.navy-radio.com

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