ang@Su-Dsn (12/22/82)
Here's a digest of the responses I got to my recent request for information on
the Racal-Vadic Triple Modem :
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From: clark.wbst at PARC-MAXC
The 3451P(A?) is a very good modem, but it can only pulse dial. I know
people who have uucp up through it, no complaints. Once I saw someone
complaining that they had a big cap hanging on the rs232 line causing it
to not run over very long distances [to the computer], but noone
I know has had and problems. I would buy one but I need tone dialing
for my internal phone system.
Would you please send me a copy of your replies after you collect them?
I will not get them, as I have asked to be removed from the list. I just
can't handle the load (50-100 letters a day, sometimes more) and have
to cut down.
Thanx alot.
--Ray
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From: Bob Clements <CLEMENTS@BBNA>
In response to your message of 18 Dec 1982 1931-EST
I can't give you much comparison info, but in an absolute sense
the Racal-Vadic triple modem works very well. I use a VA3451 which,
fortunately, my employer paid for. The acoustically coupled version
doesn't make it. Many errors. I think that's beyond the state of
the art. The Vadic is quite expensive, though - like 750 to 1000
bucks, depending on features. If someone else is paying, or if you're
richer than I am, go for it.
It doesn't have a dialer or a lot of bells and whistles. It's
just a good modem. I'm not up on the competition,
either. When I got this one about two years ago, there was none.
Maybe there is now.
/Rcc
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From: Bob <Carter at RUTGERS>
Hi,
I am transmitting this to my host on a Racal-Vadic VA3451PA (the
triple, with retrofitted auto-dialer). This unit has been in
service for two years. Aside from necessity for one repair, it
has been very satisfactory under @i(heavy) usage.
The bulk of my work is at 1200 Vadic protocol (else why spend the
money for this unit?) although there has been a fair amount of use
at Bell 300. I have used it only occasionally at Bell 212A 1200.
I have heard rumors that the 1200 baud Bell protocol setup on this
unit is 'delicate' but have not had any malfunction in the limited
use I have made of it.
Vadic 1200 seems solid. Some the connections are @i(long) distance,
often through third-party carriers, but the error rate has been
low, and confined to an occasional 'y' or '|' (these characters
appear to be the unit's way of handling random noise.)
The @i(only) time the unit failed to give satisfactory service was
over a very long hop inside what must be the world's flakiest
university PBX. It has always been satisfactory on public lines.
For the first year I had it, I left the unit plugged in all the
time. At about the end of that first year, it failed, going
irreversibly into test mode. Vadic's East Coast service facility
put it right in about two weeks, portal to portal. The price was
in the high reasonable range.
During repair, I had Vadic install the autodialer. It is a convenience,
but it could be a much greater one, had it been better designed. Its
defects, in descending order of seriousness:
a. The memory is volatile. Unless you
leave it plugged in always (and thus
on), it forgets all stored numbers.
I now switch it on and off with every
use, since I am convinced that leaving
the unit on constantly caused the one
previous failure. I got Speed-Calling
and let the TelCo do the remembering.
b. The autodialer will only transmit pulse,
not tones. I think this is a major misfeature.
The doc (minimal) hints at a later conversion
to tone. Vadic tells me by phone that no
implementation is planned. They will be happy
to send me a separate tone autodialer for
more than some micros cost. *Sigh*
c. The autodial function is @i(slow).
In particular, you cannot transmit commands
to the auto-dialer at normal typing speeds.
If you try, all commands after the first
get discarded. The solution:
I wait. It beats flogging my finger.
d. It prompts with cutesy-poo messages.
My characteristic use sequence is shown.
Me: 3451PA:
^E<cr> HELLO, I'M READY...
*
d<cr> *NUMBER?
2<cr> 2
<cr> DIALING...
[There is now a @i(long) (well, about two-second)
delay. Part of that is the dialer, part of it is
TelCo, because Speed-Calling is very slow if the
number code is entered alone, without a confirming
# tone. Of course, the fact that there is no # tone
is the dialer's fault, too.]
ON LINE.
In summary: The basic VA3451 seems a very satisfactory (if quite
expensive) unit. I am convinced that it should be switched on and
off between the power transformer and the AC line, despite the fact
that the method of construction invites you to do otherwise. My
unit has been satisfactory through several thousand of hours service
per year.
The autodialer is very idea, desultorily implemented. I use it, but
it pulse-only design and slow speed remain a constant annoyance.
I'd buy the unit again. Hope this helps.
_Bob
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From: Leonard N. Foner <TK.FONER @ MIT-OZ>
I have a VA3451 trisexual type which works very well. I got it
secondhand because it supposedly had problems, but it's worked
flawlessly for a long time. Every so often it goes ino diagnostic
modes (like for a week at a time every six months) for no discernable
reason. This was why I got it cheaply. I haven't heard of any other
units doing this, though.
It gives me rock solid communication to anyplace I call (all local).
In general, a good buy, if you can take the roughly $850 list price.
Have fun.
<LNF>
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