[HATS] DTMF with ATV repeater

[Gene Harlan]

Looking to see if anyone has more ideas to help us out:

Equipment:     Intuitive Circuits ATVC-4 Plus repeater controller
                      Motorola Radius control receiver

Problem: Most of the time, we have a problem with the DTMF tones when pressing 2, 3, A, or B when trying to control the ATV
repeater.

Sometimes the #1 is a problem as well, and sometimes when I try everything (all DTMF) works. Now, you need to know this is the first
repeater that I have set up or worked on to any degree.

It does not seem to make a difference what radio is used to send the DTMF tones, although a few days ago several of us were at the
repeater site and had 4 radios to try. One work work quite well, and three would not (again, this is right at the site). Another
different radio, from home almost never workes with the DTMF mentioed above. So, I think we have ruled out the radio sending the
DTMF as a source of the problem since we have so many that it does not work with.

The Motorola receiver audio is connected to pin 11 out of the back of the radio (in case you are familiar with the Radius). What
little information I have on this radio says that this is the pin to use to get tones out if you are using 9600 baud packet. I would
think we would want that same condition. I took my scope to the site Monday and get 300 mv p-p out of the radio when the tones work
as well as when they do not work (decode properly). Touchtoning (is that a word?) any of the DTMF seems to give similar amplitude on
the scope. Yet, we only have trouble with DTMF tones that are higher (2, 3, A, or B mostly). When these tones stop being decoded,
the other tones still work. I also see that there appears to be noise, as if the squelch is always open, when it is not receiving
tones.

The ATVC-4 Plus has a place for a 100 ohm resistor across the control audio input and we had that in place to start, but now we have
it lifted and "maybe" it works a little more of the time. But, we need to have the tones work all the time.

Before moving to the repeater site, I had a different receiver hooked up and did see some similar problems, but intermittent, just
as it is now.

The good news is, I can always turn the repeater on and off. Doing that uses the 0 (zero), * and # keys (low tones).

You may reply direct at atvq@hampubs.com and if there any that want to hear the results, let me know and I will share what we learn.

Gene Harlan - WB9MMM
NEW - Name Tags by Gene
Harlan Technologies - publisher of Amateur Television Quarterly
ATVQ@hampubs.com
815-398-2683 - voice
815-398-2688 - fax
http://www.hampubs.com