Rear Control Head Spectra

chiefhal3 · Post by **chiefhal3** » Mon Jul 12, 2004 3:25 pm

Is there any problem using an extension cable to hook up a rear control head on a spectra using two control heads. I am considering puting my A9 spectra in my office downstairs and the rear control head upstairs. I am needing about 50' of extra cable. I was thinking perhaps I could just get a DB25 male to DB25 female serial cable. Plus run appropriate wiring for 12v power coming from the same power supply as the one for the radio, which by the way is a deep cycle marine battery with an automatic tricle charger on it. This would give me control, listening, and transmitability both upstairs and downstairs.

Any comments? Particularly equipment and safety issues.

Mike B · Post by **Mike B** » Mon Jul 12, 2004 4:54 pm

Motorola made some Systems 9000 50 foot rear control head cables for the Syntor X 9000 (I think they were intended for large fire engine use). They used the X9k T connector.

On the Spectra, one of these rear cables would only work going from a Siren/PA or VRS cable (or with a new/custom DB-25 connector on the rear cable). However, these were not RS-232 cables. The Systems 9000 2 wire serial bus and busy line has its own shielding (it is even shielded from the other wires in the cable) and the serial data lines have the correct twist and impedance. You will not get this from any RS-232 cable. The microphone wire also requires its own shielding, especially on such a long run.

I do not remember, but is it possible the rear head might be able to get its power from the rear cable itslef.

In the past, I have seen some eBAY auctions for really long Motorola Systems 9000 remote control head cables. The cable, control head, speaker and microphone were all packaged in a suitecase.

Post by **wavetar** » Mon Jul 12, 2004 4:59 pm

Shouldn't be a problem at all, especially if you use a quality heavy duty cable with end-to-end shielding.

Todd

tvsjr · Post by **tvsjr** » Mon Jul 12, 2004 6:56 pm

We've done this in the past to run a radio in one room (where antenna and power supply was plentiful) to another.

A few notes:
Most DB25-DB25 serial cables do NOT have all of the pins run through. They commonly only run the pins necessary for serial communications through. As you can see from the model-specific page http://www.batlabs.com/spectra.html, you'll need more than that. Look for a printer extension cable (the DB-25/DB-25 models, not the DB-25/Centronics ones)- the good ones will boast having all the conductors run through, along with fancy shielding. If the cable is nice and small and flexible, it probably doesn't have all the lines you need, nor good shielding.

When we did it, we hand-wired an extension cable, but that's a fair amount of careful work.

Before you run it through walls/tight areas, I'd lay whatever cable you purchase out, cable it all up, and test it out. Then, if it doesn't work, it's an easier return.

chiefhal3 · Post by **chiefhal3** » Tue Jul 13, 2004 12:56 pm

Is there anything special about the cable for the rear control head? Can I just use two of the cables that go to the front control heads, pluging one in one of the DB25 plugs on the radio and the other into the second DB25 on the radio. This is a 110 watt VHF unit.

Mike B · Post by **Mike B** » Tue Jul 13, 2004 10:14 pm

I remember the rear control head cable has no orange ignition sense wire. I do not remember if it has a green power wire or not. I think there is also supposed to be a VIP relay pod with a pair of speaker connectors on the back of each control head. One relay pod connector goes to the control head cable speaker connector and the other goes to the speaker. These relays switch between the front and rear speaker as you select one of the control heads, when the VIP port is programmed correctly.

chiefhal3 · Post by **chiefhal3** » Wed Jul 14, 2004 4:40 am

I was under the impression that both control heads and speakers would be working simultaneously, as in you didn't have to switch between. Is this not the case?

chiefhal3 · Post by **chiefhal3** » Wed Jul 14, 2004 5:36 am

Can you also run two control heads on a 110 watt A7?

Mike B · Post by **Mike B** » Wed Jul 14, 2004 6:22 am

You can have two HSN4018 speakers at the same time. Their combined impedance should be about the same as a single HSN6001 speaker. The volume at BOTH your office and radio location will be set by whichever control head is active. The relay pods are simply a way of automatically switching the speaker audio to the active control head. You could add a manually adjusted 8 ohm L pad volume control at one of the speakers if you need to trim the audio "balance" for different room ambient noise levels / acoustics. You might also want to think about how to mute/adjust the volume in your office without messing up the speaker volume at the other radio location or vice-versa. Muting could be very important if you have "guests" in your office and your radio system uses encryption.

The rear A9 head is part number HCN1071. I do not know of any A7 rear control head part number. I have only seen the RSS rear control option show as available on S9000E (i.e. A9) control head radios. However, people have been successful at running two Syntor X 9000 front control heads in parallel. The A7 and A9 work a bit differently, so there is no grantee two front A7s will work together, but you might be able to get away with it. You might have to modify the power on/off switching jumpers on one A7 head.

chiefhal3 · Post by **chiefhal3** » Wed Jul 14, 2004 7:28 am

Ok, thanks to everyone for the help. I will have plenty to play around with later this week or this weekend. I plan to hool everything up and test it as suggested, then I get to have the fun of fishing the cables through the walls. I am considering putting flexible conduit in if I can find some big enough. Since I am dealing with all interior walls, I don't think insullation will be a problem plus I think I can get to the top plate above each wall in the attic. Just not sure about fire stops but I think they make a long drill bit if I can find one of a large enough diameter.

Boy, I wish I could have done that when the house was being built.

Big Blue TO/\/\ · Post by **Big Blue TO/\/\** » Tue Jul 27, 2004 9:43 pm

We have 2 of our ambulances with Spectra 110 watt setups, and both have front/rear heads.
*The relay pods make things nice.
*I have not had much issue just telling a head it is a rear or front via software. I never got hung up on using the 'actual' ones, and have had no problems
*there is specific software version for programming a front or rear head
*the rear head should not have any power leads, ignition sense, etc
Good luck, and keep us posted
Tom

Post by **alex** » Wed Jul 28, 2004 5:49 am

I believe that if you program the rear control head as front, you will discover that the control head in front and back will mirror themselves. I found this out once by accident. I haven't played with a dual head spectra setup in a while, but if I recall, this happened by accident, and I believe that is what caused it.

-Alex

60hzEE · Post by **60hzEE** » Thu Jul 29, 2004 10:51 am

I have a brand new rear mount cable that's about 20 feet long. If you would like to trade a front mount with the orange and green wires, I'll do it.

Or, I'll sell it.

PM me if interested.

Lee