Random Question...

Jonathan KC8RYW · Post by **Jonathan KC8RYW** » Sat Jan 26, 2002 11:16 pm

Why does Motorola show the control-head connected directly to this Motrac?
<img src="http://141.209.214.215/ham_radio/Motorola_Motrac.jpg">

Who ever connected the control-head DIRECTLY to the rig? Wouldn't the PL-259 connector get in the way, being connected on the front?

Is my observation valid?

Post by **HumHead** » Sat Jan 26, 2002 11:39 pm

Got me. I was wondering the exact same thing about a Mocom 10 with the same configuration that was on ebay the other day.

Monty · Post by **Monty** » Sun Jan 27, 2002 12:07 am

Hi:

In the earlier days of Mobile Radios, they
had a Control Head, Control Cable, and the
radio was mounted in the trunk.

When a Technician wanted to service the
Radio, it was sometimes much more practical
to use the Control Head that could be mounted
directly to the radio while it was on the
Service Bench, and not fixing in the trunk
of the vehical.

This was especially helpfull if one could
not aford the more elabroate Test bench
Set up with all the cables and meters.

Monty

PETNRDX · Post by **PETNRDX** » Sun Jan 27, 2002 12:29 am

They also made a "front mount" cable for those things.

I have actually seen them like that photo, only with the power cable coming out between the head and chassis, installed in logging trucks and heavy equip.

VERY old.

Jonathan KC8RYW · Post by **Jonathan KC8RYW** » Sun Jan 27, 2002 12:53 am

On 2002-01-27 03:29, PETNRDX wrote:
VERY old.

I wouldn't say "old." I mean, the Earth is old.

I think the correct term is "vintage."

_________________
Jonathan KC8RYW

<small style="color: springgreen; ">I'm voting Green in 2004! <a href="http://www.takethepledge.com/">www.take ... /a></small>

<font size=-1>[ This Message was edited by: KC8RYW on 2002-01-27 03:55 ]</font>

Jonathan KC8RYW · Post by **Jonathan KC8RYW** » Sun Jan 27, 2002 1:01 am

Another question while we're walking down "memory lane" : why the heck did every trunk-mount mobile have a keylock? What purpose do/did these have with a radio?

Wes · Post by **Wes** » Sun Jan 27, 2002 2:07 am

I have seen both the Motrac and Mocom 70 made like this and mounted as single piece radios under the dash of a vehicle.

Imagine trying to fit one of those things under the dash of one of todays vehicles.

Wes

kd6kml · Post by **kd6kml** » Sun Jan 27, 2002 8:34 am

This configuration is dash mount 1960's style. In a large truck in those days it was easy to mount a radio like this. We had a low band Motran dash mounted in a late 60's International Loadstar. No problem fitting it in, and its size went well with the 32" or so diameter steering wheel (no power steering).

The lock on the radios is to prevent tampering more than to prevent theft. The idea was to keep the end user from playing with the internal adjustments.

Jonathan KC8RYW · Post by **Jonathan KC8RYW** » Sun Jan 27, 2002 3:02 pm

On 2002-01-27 11:34, kd6kml wrote:
The lock on the radios is to prevent tampering more than to prevent theft. The idea was to keep the end user from playing with the internal adjustments.

I suppose that is a good way to prevent radios from "mysteriously" becoming mis-aligned, or from "mysteriously" over-deviating with a quiet whisper.

April · Post by **April** » Wed Jan 30, 2002 1:04 am

The lock IS to keep unauthorized personel out of the radio as the radio had a very leatal voltage in the transmitter upwards of 800 volts!!!!!

I learned from one of the best MOTRAC techs.

Jonathan KC8RYW · Post by **Jonathan KC8RYW** » Wed Jan 30, 2002 11:37 am

On 2002-01-30 04:04, April wrote:
The lock IS to keep unauthorized personel out of the radio as the radio had a very leatal voltage in the transmitter upwards of 800 volts!!!!!

I learned from one of the best MOTRAC techs.

Really?! 800 Volts!?

Note to self, avoid MOTRAC's. Are there any other radios from that decade that I should avoid without electrical line-man's gloves?

kd6kml · Post by **kd6kml** » Wed Jan 30, 2002 12:11 pm

You might want to steer clear of the big tube type PA units that Motorola and GE made in the 60's and 70's. The plate voltage on my 1/3KW General Electric low band station is 2000 volts. (It's even old enough the the freq range is listed as 42-54)

There's no band like low band...
More signal, less noise...

Josh

R F Burns · Post by **R F Burns** » Fri Feb 01, 2002 5:25 am

On 2002-01-30 04:04, April wrote:
The lock IS to keep unauthorized personel out of the radio as the radio had a very leatal voltage in the transmitter upwards of 800 volts!!!!!

I learned from one of the best MOTRAC techs.

I learned from a Motorola T-Power's final as I was tuning it. Fingers slipped and ZAP!! -got to know what a few hundred volts feels like. Hey, I was young (18). Thank gooodness it was at idle current. That's what I mean by "once bitten..."

-RF Burns

perthcom · Post by **perthcom** » Fri Feb 01, 2002 4:00 pm

When I started, there was a local cabbie that had 2 Motorola Twin V's (6V or 12V).
It used a motor/generator set for the high voltage. It was all tube.
I can't remember how many amps this thing took, but he couldn't run it at all without the engine running to get the voltage high enough to get it working. It took about 10mins warmup to get it on-channel and stable..lol

Bruce

Tom in D.C. · Post by **Tom in D.C.** » Fri Feb 01, 2002 4:24 pm

Bruce: Don't forget GE coffin boxes, circa 1946. I remember when the taxicabs in DC got them right after THE war. I wonder if the weight of radios such as these cut the car's gas mileage!(G)

Tom, W2NJS
...in D.C.

R2670 · Post by **R2670** » Fri Feb 01, 2002 4:42 pm

back to the topic, I installed many of these
in farm equipment in 70's,some was setup as
phones with addon two-tone decoders for incomming calls. To make a call,pick up the mike and call for an operator.....and call ...........and call...... I think PCS was a drug back then.

radioconsult · Post by **radioconsult** » Fri Feb 01, 2002 6:41 pm

OK all you radio newbee's. If you never took a brand new Motrac U43MHT out of the box for the first time along with a new manual and two 2135 keys, then you are still wet behind the ears when it comes to real radios. Yes Motorola made a control head for front mounting the radios under the dash.
The good old days! Now for the brain teaser, how come we use 50 ohm coax as a standard for radio communications. Any guesses.

RC

techie · Post by **techie** » Fri Feb 01, 2002 11:58 pm

I cheated.. (google search)

It's a compromise between maximum voltage transfer (60 ohms), and maximum current transfer (30 ohms).

As always, devised and speced by the US military.

http://lists.contesting.com/_towertalk/199906/0185.html

Paul · Post by **Paul** » Sat Feb 02, 2002 1:41 am

FYR, while in my mil service, I also met a lo band Motrac (F1=40.00) of this configuration.
It was wall mounted(!) in a small Police station ,in a remote location, somewhere in north Greece.
I've been told that this radio was being serviced by V.O.A. technicians of the near-by radio station.
The PD now gone VHF hi; they installed a bunch of repeaters to do the same job...

Post by **firemed9** » Sat Feb 02, 2002 3:23 am

i used to have two of these radios in this configuration. I sold one on ebay, and sold one to a guy around the corner from me. This was back when I was collecting and not really knowing what I had. (I am kicking myself in the a$$ right now). I was wondering back then why I got so much for this configuration radio

SD70MAC · Post by **SD70MAC** » Sat Feb 02, 2002 5:05 am

This set up is semilar to radios used by railroads(years ago).The railroad radios are called MOTRAN.You could take this radio out of a locomotive and put it in a caboose.If i had a scanner i could shoe you a picture because i have the service manual and radio.These radios worked on 12v/64v.

Jonathan KC8RYW · Post by **Jonathan KC8RYW** » Sat Feb 02, 2002 11:51 am

On 2002-02-02 08:05, SD70MAC wrote:
This set up is semilar to radios used by railroads(years ago).The railroad radios are called MOTRAN.You could take this radio out of a locomotive and put it in a caboose.If i had a scanner i could shoe you a picture because i have the service manual and radio.These radios worked on 12v/64v.

I've always wondered why trains use 64 volts. Any rhyme or reason behind this?

Will · Post by **Will** » Sat Feb 02, 2002 8:33 pm

The Motrac was also available in 64-72 volt for the Railroads.

BTW Motran, is pronounced MoTrain !

Ray D. O'Mann #2 · Post by **Ray D. O'Mann #2** » Sun Feb 24, 2002 9:16 pm

Boy, there's some old fossils in here, and I'm not just talking about Motracs ;.)

Cowthief · Post by **Cowthief** » Tue Feb 26, 2002 4:03 pm

Hello.

SMTL 44.34 MC

Try Indust comm, in San Antonio, TX.

Trade-in on dash mounts a few months ago.

Most were mounted in transtar 9600s, would not fit in the modern truck-tractors.

Thank You.