Which hardware decoder did you use?
de WD7F
John in Tucson
----- Original Message -----
From: "Coy Hilton" <[EMAIL PROTECTED]>
To: <Repeater-Builder@yahoogroups.com>
Sent: Tuesday, July 27, 2004 6:37 PM
Subject: [Repeater-Builder] Re: Deviation Limiting/Linearity
I converted a MSR2000 VHF radio to repeater service. I did not have
the beloved Squelch Gate card. So I didn't use any cards. They are
always a source of problems in the audio path AND the card
connectors tend to get flaky. I used a few push-on jumpers on the
back plane to bring all of the necessary connections to one of the
card connectors in the shelf from the receiver and transmitter
exciter. I built a DB interface on a stripped card and did full
alignment of the transmitter and receiver. The deviation from input
to output is very nearly the same because we made the adjustments in
the controller that way, using a DTMF 3 It tracks very well. Some
like using all of the cards that they can find. I beleave in
KISS, "Keep It Simple & Sanitary".
As far as Echolink, IT is one of the BEST pieces of software EVER
WRITEN for the ham community, with 1 exception and it is not
Jonithans fault. The Software DTMF decoder doesn't work well, I
beleave this has to do with suttle deviations in clock frequency
from sound card to sound card. I added a hardware decoder after a
few weeks of fighting the software one. And have had NO problem with
it sence.
73 and good luck
AC0Y
--- In Repeater-Builder@yahoogroups.com, "WD7F - John in Tucson"
<[EMAIL PROTECTED]> wrote:
>
> Actually, I have two problems so it might take two threads. (Long-
winded too...no less)
>
> Repeater: MSR2000
> Controller: CAT250 interfaced via Squelch Gate card.
>
> I have been chasing my tail on two issues. One is deviation
limiting and the other is deviation linearity. It seems that if the
deviation is not linear when setting up IDC/Repeater Level and the
deviation limiting in the receiver, if has an adverse effect on the
DTMF decoding in the VA3TO interface that I use on Echolink. IRLP
and WIRES decoders work nearly flawlessly with the same audio. I
found that the 147 side of the keyboard would not perform well for a
lot of DTMF sources if the deviation didn't track pretty closely
from 0 to 3 K or so. We check it by putting in a 1K tone @ 1K
deviation, 2K deviation and 3K deviation, etc. There seems to be a
couple of schools of thought. One, adjust IDC/Repeater level so it
tracks 1:1, e.g., 1=1, 2=2, 3=3, 4=4, etc. The other is to check
the deviation with no input and adjust the deviation to compensate
for noise in the exciter, e.g., 1=1.2, 2=2.2, 3=3.2, etc.
>
> We have done it both ways. It's seems pretty tough to get the
linearity AND the deviation limiter in the receiver aligned so that
the deviaton is linear and limited to about 5K and see a nice
undistorted audio waveform. After we had done an alignment and was
fairly satisfied with the results, a month or so later, we began to
have what appeared to be an intermod or spur problem which would
break squelch and key the repeater. We thought SURE it was a noisy
rig somewhere or the TV Channel 11 spur we found a few months ago.
We chased it around several days. We re-soldered suspected back
plane pins on the R1 Audio and though we fixed it. Then it comes
back again. Changed out the R1 Audio card and it worked for a day
or two, and it's back again! Thought it was the Squelch Gate card
and checked every solder joint a few times. Used a scope to look at
everything. This morning at about 4 AM, I put my adjusting tool on
the L201 deviation limiting adjustment in the receiver and cracked
it a little CW (higher deviation allowed) and the problem went
away. I could see the audio noise waveform change on the scope at
the output of the receiver. I can easily find the ragged edge so I
know it's this adjustment. I even put the suspected R1 Audio card
back in and it works good. However, 147 won't work on K7IOUs
Kenwood (again) now....because the deviation is no longer linear.
>
> By the way, the repeater still sounds great even if the deviaton
is not linear...so long as the limiter is working.
>
> Can any of you "gurus" with lots of experience give me a hint on
the alignment? Or should I throw away the VA3TO interface? Skipp, I
have read your alignment procedure a hundred times, and it makes
sense on paper, but I'm not confident that I'm doing it right.
>
> I would think that the deviation limiting would not have an effect
on the linearity, but it seems that it does.
>
> de WD7F
> John in Tucson
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