Batboard

Ok, I know that before the clean-cab radio standard was adopted by the AAR and stuff, that railroads had stuff crammed everywhere and usually in limited channel quantities (like a 4 channel Micor for instance).

Now, I have an old WABCO branded base radio at home that I guess "works" but I've never done anything with it the past 7 years I've had it, but the other day I got one of those fun Railroad FM Micors, low and behold, it has the exact same 23 pin round connector that the WABCO model has on it...

So, the question for you old-tyme railroad radio folks out there, that can predate the clean-cab, what is the pinout on this?

I'd like to be able to either hook up a regular micor head to it, or a jury-rigged one with an RJ-45 in order to put a standard hand-mic on it.

Or at the very very least, get it powered up with 12v with a speaker so I can listen to stuff.

This is the information I recovered from decoding the model number.

MICOR|Railroad FM Radio Model: R43RTB1190BA

R= Railroad
4= 40 Watts
3= VHF
RTB=Micor intermittent duty base
1= csq (NO PL!)
1= Narrowband (5khz)
90 = Four frequency transmit, four frequency receieve


It isn't worth much more to me than another fun project to tide me over during the lulls in my week.

-Josh

R43RTB is a 120V AC powered radio. There is a noisy switching converter inside which powers it from regular AC power.

The original head is a heavy cast aluminum thing which has a 4-channel plus scan feature.

Unfortunately I gave away my manuals and radios years ago so can't help you there. The switching power supply is so noisy that it will drive you nuts if you try to listen to it at home...

really?

I don't see anything that resembles a power supply in there.

Maybe I should look closer? I see a lot of empty space unless of course, it's right down the middle, but I'm not familar with micor radios at all, but KC8RYW is (because he's such a fan of old crystal crap) I'll run it by him.

I'll judge for myself the noisiness of the power supply, and then see what I can do, maybe I can leave it out in the garage and just pipe the audio into my radio room lol.

-Josh

The micor, motran, wabco and other locomotive radios with the 23 pin connector used a special AAR 4 or 8 channel control head. The volume and squelch controls are inside the radio so a regular mobile head will not work.

The pinout on the 23 pin AAR connector is:

1. negative 12V or 120V neutral
2. 12 or 72 volt positive
3. negative 72v or 120V hot
4. A+
5. ground
6. audio ground
7. Mic
8. spkr hi
9. PTT

10 ch1
11 ch2
12 ch3
13 ch4

17 squelch ind
18 ch select return

21 A+
22 PL
EDITED & CORRECTED 10/3

CH SEL return is 18 not 16 as previously listed.

There is a local volume control for the speaker in the control head.

The best way to check a RR micor or motran on the bench without an AAR control head is to just find the 13.8V power supply output point in the radio and connect your bench supply, use a Motorola test set on the TX and RX test connectors for your audio and locate and ground the ch1 select line.

I may be able to get my manual in a few days if someone else can not confirm the pinout before then.

The radio should have either a 120VAC supply or a 12/72 DC supply board. If that is missing, you can connect a 13.8V supply to the power supply output point as I mentioned for bench testing.

Wabco had a radio? That's interesting. The original WABCO facility is 1/2 mile from here.

yes they did...

I think Harmon was in on it too, I have a wabco from the seaboard railroad (13.8vdc unit) and a Harmon unit with a 120v transformer and base (with disconnected wiring) netiher radio has a control head, both were 4 channel units, I've only gotten the Harmon (Chessie radio) to power up and tx by crossing lines, but never bothered to get to work properly since it didn't really matter.

This micor is just a fun experiment... for fun!

-Josh

The "B" in the Micor model # indicates it has the 120V supply board. Of course you could also use 13V DC directly, but that creates somewhat of a kludge setup.

WABCO made quite a few radios, primarily (exclusively ?) for the railroad industry. It appears that their radio engineering staff consisted of people who had come from RCA. The WABCO radios look very much like RCA 700/1000 mobiles, both physically and electrically. Such radios are pretty rare today. I believe they also re-labeled some hand-helds with the WABCo name, specifically those modular Repco/Tek style things from 1970 which must have been bought by over a dozen different names...

Back in 1998, we began changing-out all of our old Wabco, Micor, & Motran base radios to RR Spectra's (minus the control head) with the AAR 23 pin connector. The Spectras ran strictly off of 13.8 volts DC.

Ironically we removed the preselector cavities from the old Wabcos, and installed them between the receiver and the antenna connector of the Spectras. It seems that our base RR Spectras were just getting terrible de-sense in the larger metro areas like Chicago & Rockford. The old Wabco preselector had sharp 'skirts' that all but eliminated the offending sources of interference.

I still have a Wabco radio key laying around in the shop somewhere. All the old Wabcos have since been trashed. Hard to forget the polished aluminum front & blue boxed radio. They were a real workhorse in their day.

Josh,

I have my Micor and Motran RR manuals and I made a correction and some additions to the pinouts on my previous post.

You can PM me if you need any more info.

Thanks, I'll give them a looking over. I may try and get something hooked up/figured on Thursday night/Friday.

-Josh

There was a later generation of radios with the 23 pin connector that used the AAR12-10 control head standard. This provided for either a 12 channel radio by use of the 4 channels select lines with either 0, low or high on the individual select line or logic signaling on the 4 channel lines plus the return line for 99 channels.

Both the analog RR Spectra and the Aerotron clean cab radios were available with the option to omit the control panel and replace it with an adapter board and a blank panel with the 23 pin connector. The radio was mounted on an adapter plate for the standard old AAR radio remote mount.

I have a "SP" RR Spectra that had a 36V only power supply and the AAR-12-10 adapter and it was programed for only 4 channels to work with an old control head for a transit system MU rebuild program. I put a standard clean cab control head on it and rewired the power supply for 12/36V.

Leave it to a government agency to buy a state of the art 99 channel radio and have it modified to work with an old 4 ch control head.

What do the RR spectras look like that are meant to operate with just a control head? I was on a train with a buddy (yes, he works there) and I was staring at one of the new Astro models but when he opened up the back of the stand it was just a control head. He was surprised as I was being used to the 'lunchbox' with the handle on it. We looked around for a minute but never saw it. That was the same day I found out that there were crappers built in to the nose of the train. That was a surprise too...

Anyway i'm wondering if they are a regular Astro Spectra deck with special firmware and a special cable to hook to the clean cab control head or what.

I have not seen one but the remote control head option was available for the original analog Spectra RR radio as well as the Astro.

There were 3 options available for the analog Spectra:

MBW496 - Single Remote - replaces the front panel with a blank panel and adds a remote 19 pin connector on the rear panel to support a remote mounted version of the standard front panel control head.

MBW654 - Dual Remote -replaces the front panel with a blank panel and adds a remote 19 pin connector on the rear panel to support the secondary remote mounted version of the standard front panel control head. A new 19 pin auxillary connector (replacing the standard AAR accessory connector) is installed on the side near the antenna connector for the primary remote control head.

MBW892 (Local & Remote) keeps the front panel control head but adds the remote rear panel 19 pin connector for a remote head like the MBW496 option.

The remote head is the standard VLN1219C front panel control head with a hardware and connector kit to mount in the standard AAR12-2 control stand opening.

Yay it works...

question...

what does the squlch ind do? power a lightbulb?

-Josh

In case anyone was wondering-
WABCO = Westinghouse Air Brake Company

Josh wrote:Yay it works...

question...

what does the squlch ind do? power a lightbulb?

-Josh

Its a COR logic output from the audio/squelch board but I can't find any version of control head where it was actually used.