apcor questions

JOHN 1807 · Post by **JOHN 1807** » Wed Oct 08, 2003 6:47 am

I finally got my employer to give me a high power apcor that I have been eyeing for a couple of years ( I finally convinced him that cellular is here to stay

) I have read the threads on converting these units for ham and gmrs use in repeat mode but didn`t get a whole lot of info, does anyone have any detailed information on how to do this? specifically what needs to be done to enable a simple repeater for gmrs frequencies? where are crystals available? and how does this "reverse frequency" in the apcor pose a problem? thanks

TomSlick · Post by **TomSlick** » Wed Oct 08, 2003 7:44 am

Disregarding the technical challenges, to be legal the unit would have to be FCC type-accepted for use in GMRS. I doubt it is, though I don't know for sure.

Still, an interesting project.

JOHN 1807 · Post by **JOHN 1807** » Wed Oct 08, 2003 7:51 am

well, I`m not really clear on the legalities, I wouldn`t put anything on the air without regard for the laws, I`m just interested in the challenge of if it can be done. I have an "unhealthy" obscesion with this particular radio, I remember seeing it for the first time back in the eighties before I became a medic myself, I thought it was the most incredible piece of electronic I`d ever seen, after I became a medic in the early nineties it was on its way out the door and several of them have been sitting around work, now I have the opportunity to have it and its rekindled my interest

PropellorHead · Post by **PropellorHead** » Wed Oct 08, 2003 7:57 am

I'd be curious as well. I have a high powered UHF apcor. Is it programmable via an RSS of sorts? Where would the data cable plug in? ANy info at all would be great. Thanx.

Louie

FFParamedic571 · Post by **FFParamedic571** » Wed Oct 08, 2003 8:15 am

From what I remember they were Heavy ... Other than that I believe they used MX or MT 500 Elements for TX and RX..

kc7gr · Post by **kc7gr** » Wed Oct 08, 2003 8:36 am

LACityFD wrote:I'd be curious as well. I have a high powered UHF apcor. Is it programmable via an RSS of sorts? Where would the data cable plug in? ANy info at all would be great. Thanx.

Louie

I used to maintain the APCOR sets for the San Francisco Fire Department's paramedics, so I can speak with some authority on this.

APCORs have MX300 series RF boards at their core, specially modified to handle a large (for a crystal controlled radio) number of channels (up to 12). They were made in two output levels: 2 watt and 12 watt.

Many (not all) contain a duplexer that allows simultaneous TX/RX. They were designed to work through repeaters, and to be able to transmit voice or EKG telemetry at the flip of a switch.

Service manuals for both APCOR radios were, the last time I checked, still available from Motorola. The part numbers are:

68-81021C05 (for the 1 watt)
68-81021C10 (for the 12 watt)

In the physical sense, they'd make a superb (if heavy) field radio for, say, amateur radio emergency services. They are incredibly durable, built like the proverbial tank. Some have said that nothing short of being run over by said tank would kill one.

The only kickers are that you would, for any frequency change, need to have the channel elements (they use the same ones as standard MX portables) recrystalled by someone like ICM, and that you would almost certainly need to re-tune the duplexer (if present) for anything other than the original channels. The rocks would run about $50 per element. There is probably enough space in the case to design and install a frequency synthesizer, especially if you remove the EKG telemetry hardware, but I've not tried it (yet!)

Hope that helps. If you have any specific questions, I'll try to provide answers.

73 de KC7GR

ASTROMODAT · Post by **ASTROMODAT** » Wed Oct 08, 2003 11:31 am

There were two versions of the APCOR radio---1 watt, and 12 watt. The 12 watt used the PA deck from the UHF 40 watt Maxar 80. The 12 watt had repeat capability, the 1 watt had no repeat capability. I would recommend that you get the operator's and detailed service manuals. The duplexer was made by Sinclair Labs, and it involves 7 cavities. 2 on RX, with 5 on the TX side. The UHF MX transmitter generated a relatively high level of broadband sideband noise, thus the need for 5 cavities on the transmit side. These will need to be retuned. The 5 MHz offset rock, that is "reversed," can be changed to +5 MHz via a jumper setting.

Larry

JOHN 1807 · Post by **JOHN 1807** » Wed Oct 08, 2003 11:50 am

Thanks Bruce and Larry, I`m going to try and obtain a service manual then look at my options, I am interested in the idea of a frequency synthesizer, thats not something I would have thought of- Thank heavens for this board! John

RADIOMAN2002 · Post by **RADIOMAN2002** » Wed Oct 08, 2003 12:07 pm

I have a few of the hi-power APCORS, it's been a project for me for some time. The comment about 12 watt doing repeat and 1 watt not is not true, it just doesn't have a repeater button. The 1 watt is still full duplex, it just talks to the accessory receiver, located in the Ambulance, on a highway callbox channel (457.???) I have successfully converted the suitcase repeaters to MX-S boards, lowering the cost of having to recrysatal the unit, and I don't see any difference, in doing it with the APCOR. As far as type acceptance, it is still Part 90, so that should also not be a problem.

ASTROMODAT · Post by **ASTROMODAT** » Wed Oct 08, 2003 1:23 pm

My point is that when someone is hunting around for an APCOR, the 1 watt version did not include repeat capability, while the 12 watt version did. Of course anything can be field modified to do most anything you might like. With the 12 watt APCOR, you dial up "REPEAT," and let 'er rip!

Larry

JOHN 1807 · Post by **JOHN 1807** » Mon Nov 10, 2003 3:15 pm

Larry, I was re-reading my post and realized that you said there is a jumper wire to "reverse" the -5 to +5 mhz offset, did I understand that right? I was going to order a 16.4 offset element but now I`m gonna hold on for a second, I finally had a chance to talk with my friend from, biomedical who, well- totally confused me saying that no matter what this will not work and that the high power apcor will ALWAYS funtion as a "base" and that by attempting to make this a gmrs repeater- I will set up a repeater "chain reaction" I think I`m about to abandon this project, Anyone with any thoughts, Please help

thanks, John

richyradio · Post by **richyradio** » Wed Nov 12, 2003 11:48 am

Hmmm...from what I remember, as stated above, it's just two MX's stuffed under metal housings w/ feedthru's....the rx unit should have no tx modules in it (no offset, either) the tx one would have a 21.4 meg offset,so you would simply order your channel element for your desired tx frequency...if by chance it has a 26.4 offset, you could order your element 5 meg lower than your tx freq...I believe I have one of those assemblys lying around..I should take a look at it and see if I am crazy or not...

JOHN 1807 · Post by **JOHN 1807** » Wed Nov 12, 2003 12:20 pm

Wow, I never thought about it that way, but I`m getting confused, would that (ordering rx element 5 meg lower) acheive the correct gmrs split?- I talked with a guy from biomedical engineering who used to service those things and he said it would be difficult to do what I wanted to do (make a gmrs repeater) Honestly even though I`m not that knowlegable-I still dont see why? It just seems like a waste to toss the thing when it was designed to be a repeater. Thanks for your reply- John Actually you are right, it does have a 26-4 offset in the tx but my problem is that I need it to be the opposite of what it is, I cant recall if it currently receives high and transmits low or vise-versa but whichever it is I need to reverse that because I know that Grms repeater frequencies work the other way around

Thanks again, John

richyradio · Post by **richyradio** » Wed Nov 12, 2003 12:44 pm

Hi...let me look at the assembly that I have to make sure we're on the same page- I'm going under the assumption the tx and rx units do not share anything in common, i.e. the elements in the rx unit being fed to the tx- and even if they are, that could be simply undone...(one would think they would, to save on the amount of elements to make that thing fly...but Motorola was never one to try to bring the cost down...) I'm trying to remember if there was a 5 or a 10meg offset between rx and tx in that thing...(The hospital operated 463/468 meg but the apcor talked thru a micor mobile- I have the aux. rcvr that the apcor talked to and I believe it was on 458 something or another) so duplexer spacing might be a problem...also, I seem to remember "repeat" was not much of a repeat at all... I think it just put the thing in tx and passed audio... you might have to make a cor/ audio gate...nice esoteric project, not sure if it's worth the effort...let me gather a little info and get back to you...either way, I think getting the radios on freq pose no big problem....p.s. gmrs- 462.xxx rptr tx, 467.xxx rptr rx ppss I'm beginning to think the 1 watt apcor did the repeat-thru- the -mobile thing where as possibly the 12 watter talked direct to the hosp 463/468 ? what do the elements say (freq) in the rx? how about tx? that'll explain alot.....wow.. just jogged my brain...does anybody w/ the apcors have the touch tone pad lower right near the handle? the big M's dope-up to make the amb. micor change channels-( via the apcor) what a horror show- those system 90 touch tone decoders were AWFUL !!! Ugh...I think I'm getting ill.....

JOHN 1807 · Post by **JOHN 1807** » Thu Nov 13, 2003 8:05 am

Thanks for taking the time to look into it, I have the high power (12 watt) version which I believe bypassed the micor altogether, It has a "repeat" mode position and from what I know that function was used to enable a handheld portable to be used in the field as the high power apcor would remain in the ambulance functioning as a stand-alone repeater, As far as whats inside I found 10 complete receive elements on the respective "med channels" on the transmit board I find only one 26.4 offset element and possibly a filter, Now from what other board members have told me the apcor acheived a 5meg transmit difference by running this 26-4 element against the selected receive element, The high power apcor respectively served as the "mobile" in place of thr micor/low power apcor setup. Basically I`m not sure what is needed to get the 5mhz split in the OTHER direction as needed for a gmrs repeater pair, Thanks again richyradio and others here at batlabs, Any further thoughts would be greatly appreciated, John- Maywood

richyradio · Post by **richyradio** » Thu Nov 13, 2003 11:13 am

Hi John, I'm going to type this in bits 'cause if I take more than 5 mins or so the thing times out and my posting goes away!! this drives me absolutely insane sometimes!!!!! I looked at the ass'y I have, it is only a 4 ch version, and each board has it's own set of elements...what they did in yours makes sense...why have twice as many elements when you can get the LO from the rx unit...your original post of changing the offset to 16.4 would do the trick, but I'm not sure if the element will go that low in freq...there's still ways out, though...I'm looking at a mx 300 manual as I type, bet there's a little white coax cable between pin 7 on the "presel 32" module (on the rx) going to pin 12 of u102 pll proc on the tx unit...I think simply eliminating this coax, installing another presel 32 in the tx unit (unfortunately there's a x3 multiplier needed by the tx in that module) and then installing a 21.4 offset , ordering correct freq channel element, and you'll be good to go (or using the 26.4 and ordering your tx 5 meg lower in freq) So..you'll need a 467.xxx element for the rx, a 462.xxx (or 457 w/26.4 offset) element for the tx unit- I'd go w/ International Crystal Mfg. Co as they do a good job on these- they even have the right flux to solder the element closed as it is stainless steel...

richyradio · Post by **richyradio** » Thu Nov 13, 2003 11:50 am

DAMN!!! dumped me twice again!!! arrgh.. time is getting shorter..let's see if this works at all at this point...I hate this- send post, tells me to sign in again and looses the post... I keep on loosing my train of thought when this happens....to make a long story short, I think I may be able to help you out if you determine it's worth the effort (try pricing that battery!) I have a large box 'o mx stuff- manuals, radios, and what looks like hundreds of new modules in boxes (I wonder at this time in my life why I pack ratted this stuff-(SH*T dumped again..) maybe 'cause it was for free and I could'nt bear to see it go in the dumpster...so if everything else is ok w/ your unit, and you want to go ahead with your project I can send you whatever you need to make it fly - (who knows, if there ever was a "official" 16.4 offset, I may have one, but I doubt it..) for free, at least some of this stuff could go to good use rather than me eventually dumping it...

"last edited by richyradio thurs 3:05 5000 times in total...."

JOHN 1807 · Post by **JOHN 1807** » Thu Nov 13, 2003 6:45 pm

thank you for so much for the information. i am a bit lost regarding the coax at the pins you mentioned as that i am not that savvy. i spoke to ICM who told me there is a 16.4 offset crystal available. so i think at this point i am going to order the 16.4 and the appropriate receive crystal and attempt to make this work.
if you get a chance, seeing as i do not have a service manual, would it be possible for you to elaborate a little bit regarding the location and repeat what i would do with this particular cable in question? from your profile i see you are local to me within 10 miles - if you do not have any objections, could i "pm" you with my cell number in the event i have difficulty understanding the process via post?

thanks!

john

richyradio · Post by **richyradio** » Fri Nov 14, 2003 2:43 pm

Hi! I noticed you put "Maywood" at the end of your post...if ICM can do the offset element, you can leave everything as is .... (I know the people at ICM, been there, very nice people from the midwest, unlike I the cynical dickhead that I am

I work in the city, drive down RT4/208 but...I stop at KIKU restuarant often, right at spring valley road! ok, let me send this before i get dumped...

richyradio · Post by **richyradio** » Fri Nov 14, 2003 2:54 pm

richyradio wrote:Hi! I noticed you put "Maywood" at the end of your post...if ICM can do the offset element, you can leave everything as is .... (I know the people at ICM, been there, very nice people from the midwest, unlike I the cynical dickhead that I am I work in the city, drive down RT4/208 but...I stop at KIKU restuarant often, right at spring valley road! ok, let me send this before i get dumped...

and I did get dumped!!!!geez, my fingerprints are probably on the unit you have in your possesion! Do you know Tom H @ Hackensack Hosp? oops, got to run...got to put out a "fire' here @ work...

JOHN 1807 · Post by **JOHN 1807** » Sat Nov 15, 2003 2:12 pm

Yep, I know who Tom H. is, didn`t know him well- he retired about the same time I began work for the same organization, Tony and TJ are there still (if you might know them) and are usually very helpfull but very busy! Yes, been to kiku also, I`m literally 5 min from there and its funny because your paw prints probably are on my apcor !!! The only thing I don`t understand is what you said about leaving the offset the way it is, won`t that put my repeater split in the wrong 5mhz split direction? John

richyradio · Post by **richyradio** » Mon Nov 17, 2003 12:39 pm

Hi John, to sum it all up, you have 2 choices: (1) leave the radio as is, and get a 16.4 mhz offset (2) do not use the rx unit as the reference for the tx unit, get both a "channel" element and an offset element for the transmitter (this requires getting rid of whatever rf cabling is going between units) I usually like keeping things "stock" but on something like this it's guaranteed to work 1st time if you just divorce the two units from each other and treat them as seperate radios...not to mention the fact that they will then use standard offset elements.....(again, I may be able to help you out w/ offsets, etc...wow...Tom retired...I know T.J. - matter of fact, he was the one who worked on apcors along w/ his partner Mike when we worked for Henry Bros. Elect. in Paramus ( by far the best radio shop on the east coast at the time- we got the esoteric work Motorola would'nt dare send to their own MSS's) .... you work w/ him in bio-med? If so, tell him Richie from "the pager room" says hi....(if he remembers 20 years ago!) Ever go to Kiku and hang out @ the bar in the back? I am a regular there in the evening some nights as I head home from work- the bartender "Johnson" (yes, that's his real first name) is a mental patient...quite entertaining...

JOHN 1807 · Post by **JOHN 1807** » Tue Nov 18, 2003 5:52 am

Hi, Thank you for your response once again! I`m a bit confused as to "divorcing" the tx and rx- I wasn`t aware I could put a regular channel element in the transmit radio as opposed to an offset- which would "play" off of the receive radio, Would that still give me the ability to use the apcor in the repeat mode? I hope I didn`t mislead you- I`m not a biomed guy (would like to be) I`m a Paramedic at the same place where TJ works (radio is my hobby) And oddly enough I think I just met the Mike you are refering to just this week (from Roch. Pk. ? ) This is a small world! I haven`t been to kiku in some time but maybe I`ll take the wife there one night and run into you! Richie- one dumb question but if I follow choice #1 and get a 16.4 offset doesn`t that mean I will still have to transmit input to the apcor on a "med channel"?-----that would not be good

Thanks again- I`ll tell TJ you said hello- John

richyradio · Post by **richyradio** » Fri Nov 21, 2003 2:56 pm

Hi John, was busy @ Empire doing finishing touches on our new "tower of power" for my employer, so did'nt get back to you sooner...basically, both the "receiver" and "transmitter" are identical radios-2 MX 300 walkie talkies stuffed under tin cans-the receive element is the "main" frequency determining device, if you will, and the thing that determines what you transmit is the offset element- a 21.4 element is basically no offset- whatever the rx element says, that's what it is going to tx on...if you move 5 meg up on the offset to 26.4, you move your tx up
5 mhz..so on the "tx" radio, if you left everything as is, and put in a 16.4 offset, your tx would go down 5 meg compared to the rx...but who knows if the radio would work w/ a 16.4- I've never tried it- hence my suggestion of "divorcing" the 2 radios...so, even though it's the "transmit" radio you would still need to order a recieve element @ 462.xxx, (and stick it in the transmit radio) along w a 21.4 offset, which would make it tx on 462.xxx(or doing the oddity of keeping your 26.4 offset and getting a 457.xxx, which, on the surface might look a little confusing...) well, got to run again..my parking garage (Lincoln Center) is $8.00 a day,
(pretty good deal) but if I stay past 7:00 pm it goes up to $33.00! so, my car is about to turn into a $33.00 pumpkin! talk to you later- Rich

JOHN 1807 · Post by **JOHN 1807** » Sat Nov 22, 2003 6:23 am

Thanks rich, I think I`m gonna give it a whirl and see what happens! Thanks again, John

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