Mocom 70 hookup

[Gocart878]

i just acquired a mocom 70 FM radio on Lowband, and im trying to find out how to hook it up, but im unsure becuase this radio has the 4 channel scan head on the top and there are more wires than holes in the back of the radio, also, i should be able to directly connect this to a 12 volt radio right? and on my wiring harness, i have a black and a red wire coming out of the harness, i take it that these arer for the electrical connections to the battery? and help would be appreciated

tyhanks
mike<>

[wb0qqk]

I have the Motorola manual for the T1159A 4 frequency
Channel Scan monitor. It works with both the Mocom 70
and later Motrac series. I can scan the CEPS-3178-A
installation detail and send it to you as a .jpeg if you'll
PM me with an email address where to send it.

Basically, control cable pins 6, 7, 8, 9, 10, 12, 13, 15, 16 & 19
go to the corresponding numbered recepticles on the monitor
unit chassis. Insert control cable pin 14 to recepticle 31 on the
control head. Insert numbered pins 7, 8, 9, 10, 12, 13, 14, 15,
16, 17, 22 & 30 from the monitor unit into the recepticles on
the control head. If a single frequency control head is used,
tape back pin 6. If this is the case, the transmitter frequency
selection is made by the monitor unit "receiver priority" switch.
If a four-frequency control head is being used, connect pin 6
from the monitor unit to recepticle 6 on the control head.
Transmit frequency selection is made from the control head
frequency select switch. Insert the remaining control cable pins
into the corresponding recepticles on the control head. Don't
forget that you'll need a fused (green) lead in 19 for receiver
power and another fused (orange) lead in 20 to key the transmitter.

The large red and black wires (separate from the multi-wire
control cable) are your 12vdc A+ and ground wire. The large
red wire goes to the battery. Be sure to use the appropriate
inline fuse in series with the battery. The large black wire can
be terminated to a good chassis ground.

[n5tbu]

It works with both the Mocom 70
and later Motrac series.


The motrac came first,then the mocom 70.
I just wanted to clear that up.
mod

[jcobb]

Regardless of where it is in the sentence, the scan head worked for the Mocom 70 series and the later series (as opposed to earlier versions of) Motrac.

And I believe they were still making the Motrac when the Mocom 70 was introduced. Or had just moved to the Motran.


Jack

[wb0qqk]

The diagram I sent Gocart878 from the Channel Scan
manual depicts a Motrac/Motran chassis instead of a
Mocom 70. I wanted him to know that the T1159A is
compatible with both models of radios. The Channel
Scan monitors only worked with the Motracs that used
Channel Elements and not the HHT series that used
crystal ovens.

BTW, I have a U73MHT drawer that is dated 1973.
I believe the Mocom 70 and Micor were both being
manufactured at that time.

[jcobb]

Wish I hadn't thrown out my 12 channel UHF Motran SP model. It cost a FORTUNE in xtals though. It had a double-thick control head for the switch for channel selection. I had 4 ch scan, and scrambler hooked up to it.

It was big and neat. Worked like a champ.

Oh, well. Not nearly enough room/time/money for ALL the toys....


Jack

[wb0qqk]

I have a 12 channel U44MST3100-SP1 Motran with an T1156B
scan head in the basement. It is a big unit and almost twice as
long as a standard Motrac/Motran. One channel was pinned for
priority receive and it allowed the operator to transmit & receive
on a second.

When the scan was on, it would automatically interrupt the
non-priority traffic and switch you back to the priority channel.
The Omaha Police used this model of radio for nearly 30 years,
while adding Micors, Syntors & Maratracs to the fleet until finally
going to their 800 mHz. Motorola P-25 system in January 2004.

I also have an 8 channel U44BBN3100-SP1 Mocom 70 that uses
a BCD decoder to change frequencies. It uses a standard 4 freq
cable and a special switch in the control head. I don't believe a
scan option was offered for this radio.

[Gocart878]

the channel scan unit i have for the mocom allows me to scan the radio frequencys

[giantcake]

Mike,

I'd setup without the scan head first to make sure the control head, the control cable, your power connections, and possibly mike hangup switch are all connected properly.

You have +12V for the radio itself (large red/black cables), then you also have a green and orange wire from the rear of the control head.

After you have it all up and working go ahead and integrate the scan head.

The reason I'd recommend this is that to make sure you have the right control cable and that it isn't broken inside, control head is OK, and all the DC power is going in the right direction. Following that, you'll need ovens or channel elements for all the channels (depending on your vintage).

-Steve

[wb0qqk]

Good advice, Steve. Always best to check the basic
functionality before adding a channel scan monitor.

Low band Mocom 70's use discrete, temperature compensated
(non-oven) crystals that plug into board mounted oscillators.
The radios came in the following ranges: 25-30, 30-36, 36-42
and 42-50 mHz.

VHF & UHF Mocom 70's use channel elements which Motorola
called resonators:
VHF: (T) K1017A (R) K1057A
UHF: (T) KXN1002A (R) K1018A

[Gocart878]

now ive got a problem, i cant seem to find the green or orange wires you guys are talking about and i cant get the radio to power up?

[wb0qqk]

Now it's time to get creative and make your own #19 & #20
wires or go to your local two-way shop and acquire the parts
for a TLN8427A installation kit.