[GreenKeys] newbe asking about HAL ST800a's on ebay

[eugene at hertzmail.com]

Thanks, John. Does seem to be a little limiting without a demodulator in
it. Drift isn't very attractive either, hi hi
I do see there is a spare socket for a crystal for another center
frequency. Wonder if that could be useful.

Did TMC make a demodulator to match?
Eugene


-----Original Message-----
From: John Vendely [mailto:jvendely at cfl.rr.com] 
Sent: Friday, January 02, 2009 4:03 PM
To: eugene at hertzmail.com; GREENKEYS
Cc: weather
Subject: Re: [GreenKeys] newbe asking about HAL ST800a's on ebay

The TMC TIS  (Tone Intelligence System) is strictly an audio tone 
keyer/modulator, with no demodulation capability.  It uses a reactance
tube 
arrangement to frequency shift an RF oscillator, which mixes with a
second 
oscillator to produce the audio output.  Frequency shift is set by a 
counter-type pot on the front panel, but the shift setting is not too 
accurate by modern standards, which can be a problem with narrow shifts.

The unit does exhibit some frequency drift.  It uses current loop or
high 
voltage keying.   The 2 kc tone center frequency is common in military 
equipment, but considered non-standard amongst amateurs.

73,

John K9WT


----- Original Message ----- 
From: <eugene at hertzmail.com>
To: "GREENKEYS" <greenkeys at mailman.qth.net>
Cc: "weather" <weather at surfsouth.com>
Sent: Friday, January 02, 2009 3:23 PM
Subject: RE: [GreenKeys] newbe asking about HAL ST800a's on ebay


While we're on the subject.

Can someone describe the major differences between the ST8000 and
ST8000A? I am sure this topic has come up before, so feel free to direct
me to an existing answer.


Also, anyone play with a TMC TIS-3A? Is this only a modulator (ie
creates a shifting audio signal in response to loop keying)? No
demodulation in it? Seems it is centered on 2000Hz with shifts on either
side. Doesn't seem to quite match the amateur high or low tones, but I
guess one could just detune the transmitter to get the tones matching
(or let the guy receiving move his dial)

Eugene





-----Original Message-----
From: greenkeys-bounces at mailman.qth.net
[mailto:greenkeys-bounces at mailman.qth.net] On Behalf Of weather
Sent: Friday, January 02, 2009 2:48 PM
To: GREENKEYS
Subject: [GreenKeys] newbe asking about HAL ST800a's on ebay

There have been several used ST800a's and several new ones as well on
ebay.
Will these units fire the old teletypes 15's. 19's & 28's?  Do these
units supply loop current so that it can be adjusted to 60ma?  Will
these units also run multiple machines, as in have several machines
copying the same signal at the same time? (I am aware there is not much
out there to copy, but I still wanted to have something fairly
dependable to use when I want to.  I understand there is still some
weather to copy from Canada, US Coast Guardn and German Weather, some
strong signals even 24/7 @ 75 baud?)
Here is ebay link to the new one:
http://cgi.ebay.com/HAL-COMMUNICATIONS-ST-8000A-RTTY-HAM-RADIO-HF-MODEM-
NEW_W0QQitemZ130278669243QQcmdZViewItemQQptZLH_DefaultDomain_0?hash=item
130278669243&_trksid=p3286.c0.m14&_trkparms=72%3A1234%7C66%3A2%7C65%3A12
%7C39%3A1%7C240%3A1318%7C301%3A1%7C293%3A1%7C294%3A50

ebay item # 130278669243
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