[GreenKeys] Mark Question

[Nick England]

Some TUs will automatically control TX/RX but they have a 7-10 second long
timeout. So you have that long to hit the next key.

Of course, if you are into RTTY contesting, then a 22 msec timeout is
probably overlong.

Nick K4NYW

On Sat, Jan 15, 2022 at 11:55 AM W2HX <w2hx at w2hx.com> wrote:

> Thanks to everyone for their input here. To clarify, the modem is a Harris
> RF-3466A. It has many options that are configurable. One option is a Mark
> Hold option. This option can be set to “OFF, ON, SWITCHED” switched means
> that the mark tone is produced whenever the RTS (request to send) signal is
> asserted. On means on all the time. The way I have this setup was an
> attempt to avoid needing to manually switch between TX and RX with some
> switch or some such.
>
>
>
> I set it up so that the exciter is set to VOX and the mark hold is set to
> SWITCHED. In this way the TX will automatically switch between RX and TX
> when the typing starts and stops and no other intervention is required.
> Kind of like a QSK for RTTY.
>
>
>
> In addition, there is a device (Black Box CAP) before the modem that does
> ascii-baudot conversion as well as 9600 bps to 45.45 baud conversion. This
> allows me to use a standard PC with a usb-serial dongle and a standard
> terminal program and not have to worry about getting down to 45.45 baud or
> using a terminal program that supports baudot. This also lets me connect
> this 9600 baud/ascii channel to my serial console server which allows me to
> telnet to any serial device in the shack – including this RTTY modem. Just
> very convenient.
>
>
>
> This Black Box CAP device will buffer the data coming in a 9600 and it is
> set up to assert the RTS line to the harris modem when there is data
> present. So whenever a character comes from the terminal program, the CAP
> asserts the RTS line and the modem produces audio for the character. When
> the character is done being sent, the audio drops and the transmitter
> reverts to receive mode (VOX). Works really well! But apparently won’t work
> for RTTY QSO (sad face).
>
>
>
> One current workaround is if I type faster than 45.45 baud. The CAP device
> will buffer up to (I think) 8K of data. As long as there is data flowing on
> the 45 baud side, RTS will stay asserted and the audio will flow as
> expected.
>
>
>
> If you want to see/hear how it is working currently, here is the end of a
> longer video showing it in operation:
>
> https://youtu.be/2qJhX7wah_Y?t=1069
>
>
>
> the whole Part 3 video that goes into the setup is
> https://youtu.be/2qJhX7wah_Y
>
> and there are two earlier parts of the project also available you in the
> link below if you’re interested.
>
>
>
> So, based on everyone’s feedback, it looks like I have to figure out a
> secondary, out-of-band method to manually initiate the RTS when starting a
> transmission and manually release the RTS line when ending my
> transmission.
>
>
>
> I have some ideas on this. But thanks everyone for their wisdom on this. I
> had a sneaking suspicion that my setup would not be good on the other side
> of the QSO.
>
>
>
>
>
> 73 Eugene W2HX
>
> Subscribe to my Youtube Channel:
> https://www.youtube.com/c/w2hx-channel/videos
>
>
>
>
>
>
>
> *From:* W2HX
> *Sent:* Friday, January 14, 2022 10:00 PM
> *To:* 'GreenKeys at mailman.qth.net' <GreenKeys at mailman.qth.net>
> *Subject:* Mark Question
>
>
>
> Hi all,
>
>
>
> I’m still working on getting set up for RTTY at my QTH. I am planning to
> start with a glass tty set up, then get my M28s wired into the set up. I am
> using a 1980’s vintage Harris modem that converts RS-232 to audio tones and
> vice versa. The way it is setup, when I type, I hear the mark/space
> transitions for each character. However, no audio is produced between the
> characters. Meaning no mark tone would be transmitted between characters.
>
>
>
> Question: How big of a deal is this when doing RTTY? I know that some TUs
> might not recognize that there is neither a space nor a mark audio
> frequency present, and may produce garbage on the screen/printer. Or, do
> most operators use a mark-hold function while receiving that would prevent
> (reduce) the garbage?
>
>
>
> Bottom line, should I go with what I have? Or work hard to make sure a
> mark tone is present at all times between characters?
>
>
>
> 73 Eugene W2HX
>
> Subscribe to my Youtube Channel:
> https://www.youtube.com/c/w2hx-channel/videos
>
>
>
>
>
>
>
>
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-- 
Nick England K4NYW
www.navy-radio.com
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