MTS (Mobile telephone system) Oldie
Moderator: Queue Moderator
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Glen W Christen
- Posts: 203
- Joined: Sun Sep 09, 2001 4:00 pm
Anybody else work on the very early mobile telephone? Used a modified Motrac with a special pushbutton control head. Dialing selected a series of capacitors to determine frequency, pulsed by a rotating cam. Three tones in sequence for each digit. Off-hook for connect was a single tone (If you didn't get dial tone, a variable-pitch whistle in the handset would bring up dial tone). Dialing at the CO was by a pair of stroger (multi-element) tubes in series. Mobile ringing was two simultaneous tones beat with the CO ring frequency 20,30,40,50,60 Hz. There were three ring generators referenced to tip and ring so one channel could support an absolute max of 30 customers. Individual control heads had a pair of the old copper vibrasponders on special tones to match the appropriate number. Rates were very pricy - $125/mo in 1965 dollars but it worked.
Hi:
Yes !!
We remember the hours and hours of nightmares
trying to work on the old Pulsars. Finally
they went to the stars, and I was able to
sleep once again.
Gone are all the Rotory Test Boxes, Channel
Elements ( Ovens ) and the Build on top design.
Only thing nice about the UHF ones is they had Duplexer which was great for the experimentor ( ham ).
If you could fix a IFR1000, you could fix
a Pulasar.
Only thing we have left of them are memeories,4" thick manuals and a few Brand
New Pulasr Control head interface Cables
Monty
Yes !!
We remember the hours and hours of nightmares
trying to work on the old Pulsars. Finally
they went to the stars, and I was able to
sleep once again.
Gone are all the Rotory Test Boxes, Channel
Elements ( Ovens ) and the Build on top design.
Only thing nice about the UHF ones is they had Duplexer which was great for the experimentor ( ham ).
If you could fix a IFR1000, you could fix
a Pulasar.
Only thing we have left of them are memeories,4" thick manuals and a few Brand
New Pulasr Control head interface Cables
Monty
Monty,
Hey, the Pulsar is a modern Johnny-come-lately compared to what Glen is talking about. They are all in the trash now & that makes you think - I was a Beta tester for Pulsar. Had a hell of a desense problem - of course the factory didn't believe it (some things never change) They ended up completely redesigning the interface box to fix it.
I still remember standing there wondering how it was possible the first time I saw a direct dial IMTS phone ring when you dialed a seven digit number. That was 10 years before Pulsar ....
Then somebody showed you how it was possible - opened up that black TLD1470 drawer unit and folded out the supervisory package. Wowwwww.
At the time I thought I must surely be looking at the most complicated piece of technology in existence!
Hey, the Pulsar is a modern Johnny-come-lately compared to what Glen is talking about. They are all in the trash now & that makes you think - I was a Beta tester for Pulsar. Had a hell of a desense problem - of course the factory didn't believe it (some things never change) They ended up completely redesigning the interface box to fix it.
I still remember standing there wondering how it was possible the first time I saw a direct dial IMTS phone ring when you dialed a seven digit number. That was 10 years before Pulsar ....
Then somebody showed you how it was possible - opened up that black TLD1470 drawer unit and folded out the supervisory package. Wowwwww.
At the time I thought I must surely be looking at the most complicated piece of technology in existence!
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raymond345
- Posts: 268
- Joined: Sat Sep 22, 2001 4:00 pm
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Glen W Christen
- Posts: 203
- Joined: Sun Sep 09, 2001 4:00 pm
If what I remember was a Pulsar, the logic board was completely discrete transistors. At the time I didn't know enough about them to work on them, but we had one that kept killing the battery. Found the power supply wasn't shutting off and would run the vehicle dead overnight.
The MTS was the predecessor to IMTS by a generation.
The MTS was the predecessor to IMTS by a generation.
IMTS = Intermittant Mobile Telephone Service 
Remember Digital Selectors, TLD1100 radios, and "operator this is JL3 3333 I would like to call......"
The Bell System called the lowband stuff (ZX) the 'highway service' and the VHF/UHF (JX-YX/QX) the 'urban system'.
What I can't figure out is that the cellular folks decided that we wern't smart enough to do cell phones. A radio guy for a major communications company and I somehow missed the 'wireless revolution'.
Remember Digital Selectors, TLD1100 radios, and "operator this is JL3 3333 I would like to call......"
The Bell System called the lowband stuff (ZX) the 'highway service' and the VHF/UHF (JX-YX/QX) the 'urban system'.
What I can't figure out is that the cellular folks decided that we wern't smart enough to do cell phones. A radio guy for a major communications company and I somehow missed the 'wireless revolution'.
I think I may have several UHF Pulsar radios in the garage. They weigh about 40 pounds each. Think they still work. If I dig around enough, may even find all the parts. The manual for them is almost as thick as the radio.
As for the IMTS systems, I can still hear the idle tone singing through the shop. Made some notch filters so you could listen to the channels and not go batty with the idle tone always on the channel.
Show me a bench tech that could trouble shoot the IMTS mobile and I will show you a tech that knew his radio repairing. This separated the boys from the good techs.
Kind of miss those days where you could change a part and actually fix the problems at a reasonable cost.
Jim
As for the IMTS systems, I can still hear the idle tone singing through the shop. Made some notch filters so you could listen to the channels and not go batty with the idle tone always on the channel.
Show me a bench tech that could trouble shoot the IMTS mobile and I will show you a tech that knew his radio repairing. This separated the boys from the good techs.
Kind of miss those days where you could change a part and actually fix the problems at a reasonable cost.
Jim
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raymond345
- Posts: 268
- Joined: Sat Sep 22, 2001 4:00 pm
Hi there from Canada. I come out of school
30 years ago where we replaced components.
It was cheap to repair. Going back to school today on surface mount parts is just as easy.
BUT the trick to-day is to have the tools to remove the diffrent parts and it is very easy also. These tools cost big bucks. The
overhead is greater than in the past.We got
service manuals with the radios. NOW it is buy/buy/buy. IMTS was very important here
because we were so remote.It is still here beside cell phones because Cells only work
near the cities.
My two pennies from Canada.
30 years ago where we replaced components.
It was cheap to repair. Going back to school today on surface mount parts is just as easy.
BUT the trick to-day is to have the tools to remove the diffrent parts and it is very easy also. These tools cost big bucks. The
overhead is greater than in the past.We got
service manuals with the radios. NOW it is buy/buy/buy. IMTS was very important here
because we were so remote.It is still here beside cell phones because Cells only work
near the cities.
My two pennies from Canada.