multi radio band installs in trunk

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Screwed
Posts: 148
Joined: Wed Aug 06, 2003 12:47 pm

multi radio band installs in trunk

Post by Screwed »

right now i have a spectra vhf in my trunk with control head. since i dont have alot of room to mount up front i was wondering if they made a control head to be used multi band.

want to get a uhf spectra or two high/low and if possible run all off one remote head.

can it be done?

and say i needed a extra battery. would you cusomize a trunk mounted battery holder or do something different so i could get the power to run all the equipment?
Batwings21
Posts: 930
Joined: Fri Jun 23, 2006 11:21 am

Re: multi radio band installs in trunk

Post by Batwings21 »

It is possible, but not easy. Motorola made dual band single control head spectra's for the feds, the only ones i see are a3 hhch heads though. They require a special switching box to connect the radios. If your still interested I can see if I can find the correct part #'s for you, but I don't think it will be easy to find them.
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radiokid
Posts: 134
Joined: Tue Nov 09, 2004 1:06 pm

Re: multi radio band installs in trunk

Post by radiokid »

I have the parts at home from the A3 type system. I will try to get the parts # off them when I get home.
Jim202
Posts: 3610
Joined: Sun Sep 09, 2001 4:00 pm

Re: multi radio band installs in trunk

Post by Jim202 »

What your asking about is like has been said before, the Feds had a dual radio (VHF and UHF) trunk mount
Spectra radios using a HHCH (A3) (hand held control head) combo. As they came, there was an encryption
box attached to each radio. They also had a siren setup. There is a SIU (serial interface unit) that
interconnects all the pieces and cables. Both radios in this package are normally 100 watt units.

I have taken this combo, removed the siren package, removed the crypto packages and made new cables to
go between the radio and the SIU. The crypto package is normally wired between the SIU and the radio.

A couple of issues crop up with this combo package. First, you need to have the crypto package connected
in order to make a change to the codeplug to remove it. Next you need to delete the siren in the codeplug.
Once these two steps are done, the errors being displayed on the HHCH should go away.

Make sure you have a good ground on the case of the SIU. This box is extremely sensitive to static. I would
not be surprised if you go to use the radio one day and it won't turn on. This is due to a voltage monitoring
circuit that Motorola has in the SIU. Had several go bad on me over the years. Got ticked off one day and
dug into the problem. Found that by cutting one pin off of one of the surface mounted intergrated circuits,
I could get the system to power up normally. This fixed all the SIU boxes that had died on me.

I also made up new cables to go between the radio and the SIU. Took the cables from the crypto unit
and used them as the source of the cable I made up. This way I only had to put a DB25 connector on
one end of the cable.

Depending on how the SIU box is programmed, will determine what you get displayed on the HHCH. I use
to have the RSS to program the SIU, but it was on a 5.25 floppy and it got damaged. Since then I have
been unable to change any settings in the SIU. Have tried a number of copies of the RSS over the years
since then, but have not found one that works and lets me get inside the SIU to change the display for
the channels.

The UHF Spectra that you normally find with this combo is in the low split of 403 to 433 MHz. They are
not easy to modify to go into the ham band segment. There have been several threads here about the
mods needed to move these radios.

The other issue that will crop up with the Spectra radios is the leaky caps. I have been lucky on the ones
I have in service. So far they have been fine. But one of these days, I expect them to fail due to the caps
causing damage to the boards.

Hope this gives you some thoughts to ponder.

Jim
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