CDM-1250 as Train Cab Radio

[RADIOMAN2002]

Let's just say that I am responsible for about 2000 train radios, (no name or locations please) and are in the middle of narrow banding our fleet. We are changing out analog Spectra's for GE Transportation (not Harris/GE)12R's. We ordered 250 of the 12R II radios, and they at this point have been a nightmare, everything from up to 10 seconds for power up, to intermittant transmit due to ID board problems. I am toying with the idea of placing a CDM-1250 in the Spectra rack, which contains the 32/72 volt to 12 volt power supply, and the AAR interface board. Our requirements are pretty simple, with only 4 frequencies. I was wondering has anybody done anything similar, I do know that there is an outfit in Memphis that has a locomotive solution using the CDM-1250.

[Will]

The CDM series has much the same input/output inter face as the Spectra radios and should connect and work OK.

[Bill_G]

I have several standard, plain old CDM1250's in trains successfully, but the customer has made the decision to go 100% Kenwood following another class 1's lead even though no one is considering going digital. It will be 12.5kc analog service. However, the CDM's have been bulletproof after 18 months of service.

[RADIOMAN2002]

Yea, it's been a piece of cake, I didn't even need to use the Spectra interface board. In 2 hours I have the power on/off control, 4 frequency control, and TX audio all working. Tomorrow, I work on the receive audio. Now that is the easy one, after I successfully set up this group, I have to make it work to replace Mitreks.

[Tom in D.C.]

I've always thought that railroad service radios were built like tanks to withstand rough usage, vibration, etc. Do you think a CDM will stand up over the long term under such conditions? I have no opinion on the question but I'm still wondering what the true answer is. Is it possible that building the old radios with such bulletproof cases and chassis was a case of overkill?

[Bill_G]

Power is nuthin but knockin metal.

But, so far modern manufacturing techniques seem to be holding up for both Mot and Ken. How long they will last is another question. They may become "consumables". Wear parts.

[KitN1MCC]

i used to be the radio Maintainer (volunteer) for the valley railraod in essex ct. i am no longer there due to some issues with new managment and "delay" from mdc-1200 that i fixed but ohh well here is a cdm in a steam locomotive

[jackhackett]

One thing you might want to do is pop off the plastic cover and check that the chassis screws are tight, and then recheck them when you PM the units as they'll probably loosen up with vibration. You can get noisy transmit audio if they get loose.

[RADIOMAN2002]

The old style radios starting with the Motrac and earlier were based on bigger is better, they were HEAVY, and the radios most often were mounted in the trunk along with all the other junk that might be carried, and would bang around into the radio box. In the nearly 40 years I have been in 2-way radio, I have only installed ONE front mount Mocom 70, because they were soooo big. The first front mount Motorola radios were Mocom35 Business Dispatcher(mainly designed for fork trucks and the like), which were also metal cased, then came the Maxar's which were plastic cased. Since those radio's was usually mounted in the passenger compartment, they didn't need as much protection, as is the CDM series.
Thanks, I may go one better and re-seat them with red Locktite. We have CDM's in all of our hi-railer vehicles for years and have never had a problem. The Mitrek replacements are in revenue cab cars, as are the Spectra's, our newest cab cars have GE/Harris Orions and P7100 series radios with dual heads. We have never had a trouble call with the Orions except when the operator leaves the cab window open and the radio gets drowned in the cab wash. So I suspect that the CDM's will do fine. I did a little more checking and the Mitrek replacement will be even easier than the Spectra. The original radios before the Mitrek were Aerotron Omega's. So all I need to do is run speaker audio from the CDM at full boat and then run it into the control head which has an 8 ohm pad. I believe I can even create a default programming file that will allow any radio in any combination, mobile, old cab and new cab car.
As far as the manufactured replacement radios, like the R12II or Gem,they are just repackaging standard mobile radio chassis's with a power supply for RR use.
I like the Steam locomotive install, the weather tight box will protect the radio well. Considering the steam engine noise, did you use an amplified speaker?

[KitN1MCC]

actually just used an external speaker. the speaker is mounted right above the engineer. i do want to get back into RR Radio work just looking for some place new to volunteer my time

[Bill_G]

Your install is nicely done. I like the box though it looks too shallow for a dash mount. Where did you put the trunk unit?

[RADIOMAN2002]

Well the boss just threw a curve ball into the whole process. Now he wants the capability of up to 16 or 32 channels. Has anybody made the CDM1250 or maybe PM400 or even a CM300 remotely control 16 channels? I have seen some tone remote control boards use BCD control line to control radios, does the CDM or others have this BCD channel select available on the accy connector?

[com501]

The CDM does have binary capability outputs on the programmable connector. I know the CDM1550 does, and I am fairly certain the CDM1250 does also. I think though its only 4 lines, (ABCD) so you might only get 16 channels on the 1250.

I have been running 1550s in several Fairbanks-Morse diesels (and one Baldwin 4-4-0) in regular freight and passenger excursion for 10 years now, no issues.

This is the same radio I will be putting in both my private varnish AND my GP38 once they are repaired, welded, and inspected....

[KitN1MCC]

would the cars they be going in start with the m1/m2/m3/m4/m6 and the radio and PA are intergated into one unit

[Bill_G]

Excellent. Good job.

[RADIOMAN2002]

Older than that, they are cars we inherited from another line. They have been totally refurbished and now need radio replacements because of narrow banding for the original Aerotron Mega and Motorola Mitrek radios. They use either Midwest heads or Comtelco's, which is the same company but with a later design(now named Lintronix of L.I. New York). There were some Spectra's in the mix too, but we don't know where those came from since they didn't work with the Midwest heads.
Making just about any Motorola mobile work on 4 frequencies is easy, I even was able to program a CM200 for 4 frequency, and install it inside the cab car version (no display, just AAR connecctors)of the Spectra Clean Cab power supply casing after removing the mobile chassis. I just don't know about the binary coding on the back plug of the CDM 1250. More research is needed. I also have a call into ICOM for their new 5000 series radio, the base/repeaters (FR5000) will do 16 channel binary coded, the mobiles(F5061) just don't seem to have that capability.
Nice install, I love those bulletproof razor back antenna's, though I have seen some of them on cars with pantagraphs get twisted up pretty good.

[com501]

Binary coding on CDMs is easy. Just don't accidentally blow up the input on a new radio. It took me three tries with Mexirola to get them to understand that NO, the radio wasn't programmed wrong, the INPUTS on the binary didn't work, and that funny continuous boop is what you get from the radio when it is programmed for binary channel control and the inputs are floating...

[KitN1MCC]

could also try a pm-1500

[Will]

I know the RR folks like standardization for the radio controls/control heads.

How about remoting the control head near the operator?

[com501]

You would have to use the CDM remote kit, I think remoting a Marlin would not be trivial.

[RADIOMAN2002]

com501:Please explain how you made the CDM work in binary, I do not see anything that would allow more than 4 select channels in the accy programming.
We cannot use the CDM head in the cab cars. The control heads are standard AAR wiring,(the PA goes through it too) it doesn't matter which radio or head you put on either, if it's set up for AAR they are supposed to work. There are 2 types we use, both binary and individual line select. I am trying to get a CDM or PM or any of the other current generation of Motorola's to work with the binary head. I know the accy connector ports can be programmed for hi or low detect, I just need to know which ones ( the numbers of the accy pins)they are and how it's programmed(what accy they are labeled) there is no description in the help menu's.
I don't see how the remote kit would make any difference, there is no mention of programming the radio for remote control. Any accy pin programming would reflect in front or rear mount configurations.

[com501]

Telex-Vega does this all the time with the CDM platform. Please review this document for details: http://www.telex.com/UserFiles/Download ... CH-009.pdf


The CDM does 16 channels, we have done many. The only caveat with the CDM when in remote mode is programming cannot normally be done through the front mike connector, it tends to fritz the radios randomly, you either need to install the head on the radio package or use the rear 20 pin programming/flash cable.

[Bill_G]

He's going to use a dash mount that is remote controlled by an AAR head through the CDM accy plug.

The Telex suggestion was good. They document interfacing to many, many models of radio which can be useful info even if you don't use a Telex console.

[com501]

It should work for him without a hitch, provided the AAR head has a binary output. If not, a simple a/d converter would do the trick.

[RADIOMAN2002]

That information is exactly what I need! Thank you very much, will post my results so that other RR's could possibly reuse the analog Spectra setup instead of buying a complete new radio. The Spectra power supply is bulletproof, so has the interface been, we have never had any problems with them, other than ones caused by water intrusion. I am using a SM50 for testing but if this all works out we will order PM300's for this job.

[RADIOMAN2002]

An update for all that have helped this project along. I used a sm120 radio, and installed in the place of where the Spectra radio chassis was in the clean cab unit. I wired it up to the existing harness and reassembled it, then tested it on our AAR test unit. Everything works fine, TX and RX audio are clean and sound excellent, frequency control for 4 frequencies is perfect. I just now need to modify the control head for more than 4 frequencies to test that portion of it. The head has to be reconfigured with jumpers that are under humiseal, that's going to have to wait until next week sometime.

[com501]

Did you actually mean an SM120? That is a DOS radio, and I am pretty darn sure it doesn't to binary channel control....

[RADIOMAN2002]

The SM was a test radio for size placement, before the powers to be will order any other radios I need to show them a working prototype and that this application will work. I was thinking of using CM series, they are about the same size and I can get either a four channel or 16 channel.

[com501]

Yup, that will work.

[RADIOMAN2002]

Now here is a wild thought, can the Clean Cab Spectra head ( basically an A-7 head ) be hooked up to say a CDM or CM radio and work? I suspect that Motorola uses the same data stream across all of their products. I might try and see what happens.

[sataraid1]

I have a stupid question ...

Does the CDM series support the 7.5 kHz channel spacing for the new AAR narrow band channel allocations? All the documentation I've seen says it only supports 12.5 and 25.

[escomm]

I have a stupid question ...

Does the CDM series support the 7.5 kHz channel spacing for the new AAR narrow band channel allocations? All the documentation I've seen says it only supports 12.5 and 25.

You mean 6.25KHz NXDN? No, it does not support this technology. Last I checked AAR had decided not to move forward with NXDN conversion immediately, if ever.

[sataraid1]

You mean 6.25KHz NXDN? No, it does not support this technology. Last I checked AAR had decided not to move forward with NXDN conversion immediately, if ever.

No, just the analog 12.5 wide/7.5 spacing in the new AAR plan. I knew they wouldn't do digital.

[escomm]

It will support 2.5KHz splinter channels, if that's what you're wondering, so yes it will be able to handle channels spaced 7.5KHz apart

[KitN1MCC]

i heard that amtrak and a few others were all getting ready for NXDN

[grump]

Amtrak has started issuing Icom F3161 portables in the field in place of Motorola HT1250s... At NJ Transit, the latest seried of radios to be issued have been Icom F50s(non NXDN) which have been falling apart on the railroad. A supervisor was recently issued an F3161 to "test" it out...
Long live my personal HT1000 that I use.

[RADIOMAN2002]

The AAR has been forcing? Well at least mandating that any new frequencies they allot are to be 6.25 ONLY. We got 18 pairs, but we are probably not going to use them. The ICOM's have not been doing well with the troops. They are 0 for 3 right now, one supervisor came back within a day and told us to remove that POS radio from his truck and put back the CDM-1250. The portables havn't fared much better also 0 for 3. Now mind you this is in analog mode too.
The ICOM base/repeaters are killer, they have worked flawlessly for over 6 months now in analog mode. They only complaint has been by the higher ups that they don't have an intergrated tone remote board. The wired in one is kinda cheezy, but looks like no more Harris MIII bases. We can put 6-8 ICOM bases in a cabinet that used to hold only 2 MIII's.

[Bill_G]

What were the troops complaints about the Icom radios?

[grump]

By far the biggest issue at NJ Transit with the F50s is that the accy/programming connector board becomes damaged from even light strain with everyday speaker mic use...
Mine went bad after a few months and many others did too. I sent mine back to the shop and it got fixed and lasted another few months before it happened again. This was despite me babying the radio and leaving a bit of slack in the cord. As a result, there aren't alot of people who use the mics for that reason.
I was talking with one of the radio techs several months back who was in the field reprogramming radios for a new channel, and he told me that there is such a backlog of radios in the shop for that very reason and that the Icom units were not recommended by the radio department due to fears of durability issues. But like any other big company, someone who had nothing to do with communications made the final decision based on the initial cost to purchase them. The radio department had recommended either Kenwood or Motorola models...
Myself, along with a few others, have our own personal(we and our bosses know its technically against the rules, so save the flames) HT1000s that were once standard issue within the railroad that we use and can count on in critical situations...

[RADIOMAN2002]

Poor RX audio, low RX audio. Poor TX range. We are trying to come up with a side by side way of comparing the radios at the same time. With the portables, I have seen that the HT-1250 will pick up a transmission while the Icom misses it. Our next test will be to install 2 radios in a test vehicle and actually have them use both for comparison.

[tvsjr]

What were the troops complaints about the Icom radios?

From my experience with the Kenwood NXDN radios, they suffer from the same issue as the Astro 25 radios - they just don't have quite as hot of a receiver. Also, the squelch tends to be significantly tighter. Sit an MT2000 and an XTS5000 side by side and you'll see similar issues.

As for the audio... that's an ICOM problem - the Kenwood radios don't have that issue. Poor TX range sounds like an alignment issue or a bad antenna.

[KE7JFF]

Interesting that Amtrak is using Kenwoodout east...out here in the conductors & everyone have XTS2500s...

[RADIOMAN2002]

OK, something you need to check,especially if you have hot key type radio operators. What I mean is people who start talking before they push the PTT. I found this to be an issue with the HT and CDM radios after I enabled MDC decode. The radio has a DOS(digital operated squelch) setting, that will blank out the first few sylables of a transmission. This offset is to prevent the MDC squawk from making it to the speaker. That's about 1/2 second, and with these hot key operators they complain of missing transmissions. Not good if you are on the right of way working. I disabled the DOS and the radio appears to be working better, but need to do some more testing. As far as the mobile installation, we reused the same antenna, so that's not an issue.We do need to install another speaker the one in the radio is crap, worse than the CDM. The Icoms do have an issue with mixed wide/narrow transmissions. They don't like them, so my suggestion is to program them wide and turn down the TX deviation, until all of our other equipment is changed over. Then go back and reprogram at our leisure, if at all to true narrow.
The XTS radios maybe leftovers, the AAR is forcing everybody to 6.25kc whether they like or not so those may be on the way out like the HT-1250's they have, since they both don't do 6.25. Because of this issue with the AAR, we actually went out and got non railroad channels for our use of non RTC operations.

[com501]

My company has been installing and repairing KW Nxdn radios for UP MOW since the summer. Every UP vehicle out here when upgraded gets the NXDN radio, even the PD. Probably haven't done much with actual road power yet, that's a lot of radios.