MAXAR 80 questions

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MAXAR 80 questions

Postby W8UU » Sun Mar 21, 2010 6:04 pm

I tried the search feature here and also looked around Batlans and repeater-builder.com. Still can't find a lot of information about the Motorola MAXAR 80 radio series. I realize they are rock bound, but does anyone have good luck using them as link radios or single channel monitors? Any known problems or situations to avoid? I know the original (white case) Maxar radios had a temperature compensation problem with the crystals in cold weather, but that was supposed to be resolved with the 80 series. Can you convert a carrier squelch MAXAR 80 to PL operation by adding reeds or do you need to add an after-market ComSpec board? How durable are these units, especially at remote locations? Any problems with base station use or in high RF environments? Csn you easily pair up a couple of radios with a controller and duplexer and make a repeater? I know a little about the Moxys and the original Maxars but nothing about the MAXAR 80.

Rick
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Re: MAXAR 80 questions

Postby Bill_G » Sun Mar 21, 2010 6:48 pm

They were an economical radio in their day. Small, easy to install, relatively easy to maintain. Fairly popular. In my opinion, not much difference between the Moxy, Maxar, and Maxar 80 except the housings. PL/DPL is done with a board that attached to the top of the frame behind the speaker. Though the model has a better preselector than most modern dash mount radios , it still isn't up for the task of a high rf environment. Not enough rejection. And like most dash mounts, there is no easy way to break out the rx path so you can add cavities or filters. As for reliability, MOT based the early Intrac series around the Maxar. They held up well. However, because of their age, and with narrowbanding impending, I'd avoid putting any effort into one except for purely educational purposes. I wouldn't build a link or a repeater just to have to replace it within a year.
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Re: MAXAR 80 questions

Postby W8UU » Sun Mar 21, 2010 7:48 pm

I'm looking at a 10 meter project. A guy on eBay has *SEVEN* brand new, still in the box Maxar 80s for sale. 2 frequency, carrier squelch, made in 1987. VHF low band 29.7-36 MHz split. Looks like they were crystalled for 31.90 MHz. Another guy from the local ham club suggested building the area's first 10 meter repeater. I couldn't find any information about the Maxar 80 anywhere, including Google and Bing searches. Your info was helpful!

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Re: MAXAR 80 questions

Postby firetech792 » Mon Mar 29, 2010 6:37 am

I've used them a lot over the years for links. They take a beating. Some of my Maxar pa's would get so hot you could probably fry an egg on them and they never burned out.
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Re: MAXAR 80 questions

Postby mfdeng5 » Wed Apr 07, 2010 6:49 pm

Hi Guys, i bought one of those NIB Maxar 80s on fleabay.....they are in sealed boxes!!! Could not believe it. Well anyway i made a mistake they are 31mhz split not 46mhz which i wanted (got caught up in moment and didnt read specs) Did anyone ever change a board out to get the higher split? I need it to receive only. Thanks Kevin
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Re: MAXAR 80 questions

Postby swg » Mon Apr 12, 2010 9:06 pm

mfdeng5 wrote:Hi Guys, i bought one of those NIB Maxar 80s on fleabay.....they are in sealed boxes!!! Could not believe it. Well anyway i made a mistake they are 31mhz split not 46mhz which i wanted (got caught up in moment and didnt read specs) Did anyone ever change a board out to get the higher split? I need it to receive only. Thanks Kevin


Kevin,
I've been thinking about pitching a best offer on one of those myself. The auction said it came with a service manual. You should be able to determine how much trouble moving it up will be with the SM. (prolly a lot, if at all!)

Depending on how tight you need a rx only unit, I'd look at hacking one of those 49 mhz "baby-com" receivers. Many of them were dual conversion, and you can find them at garage sales and resale shops for next to nothing. The 3357/disc stage is easy to add squelch function, and if ya need it a lil tighter, adding some add'l tuned circuits at the front end shouldnt be too difficult.

If that Maxar did come with a SM, take a look at the scematic for me and see if it has a 10.695/.455 IF scheme and post back if ya dont mind. If it doesnt come with a SM, that's a deal-breaker to me. In this vein of the hobby, ya got be able to self service your equipment.
tnx,
s.
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Re: MAXAR 80 questions

Postby KitN1MCC » Tue Apr 13, 2010 3:05 pm

if you were looking to build a 10meter rpt get a couple of micors. then set up the maxar 80s as the mobile and sell or give them to the club members
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Re: MAXAR 80 questions

Postby k2hz » Wed Apr 14, 2010 6:37 am

mfdeng5 wrote: Did anyone ever change a board out to get the higher split? I need it to receive only. Thanks Kevin


The whole radio except the TX PA is on the main board. The PA is also frequency specific. So, you would need to change everything but the plastic case to change frequency range out of band with a "board" swap. A frequency change of the unit would mean repalcing probably every tuned circuit. Both TX and RX have limited bandwidth even within the design range. They will not do a wide frequency split. Retuning is required to move as little as 1MHz in the designed bandsplit.
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Re: MAXAR 80 questions

Postby jackhackett » Wed Apr 14, 2010 7:34 am

I looked at the schematic for those, lowband came in 3 ranges, M, H and HH (why they didn't call them "L M and H" I don't know.. it's Moto, go figure) and there are a whole bunch of parts whose values change from one range to another... no way would it be worth trying to convert one.
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Re: MAXAR 80 questions

Postby escomm » Wed Apr 14, 2010 8:14 am

jackhackett wrote:I looked at the schematic for those, lowband came in 3 ranges, M, H and HH (why they didn't call them "L M and H" I don't know.. it's Moto, go figure) and there are a whole bunch of parts whose values change from one range to another... no way would it be worth trying to convert one.

Perhaps because of the fabled 25-30MHz units? Were those "L" ?
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Re: MAXAR 80 questions

Postby jackhackett » Wed Apr 14, 2010 11:38 am

escomm wrote:Perhaps because of the fabled 25-30MHz units? Were those "L" ?


Ah, that's it.... the "Maxar" manual shows 4 splits, L,M,H,HH, "Maxar 80" only shows the upper 3 splits.
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Re: MAXAR 80 questions

Postby swg » Wed Apr 14, 2010 3:10 pm

Jack, I dont have a SM or even a schematic for this series. If I could trouble you to enlighten me on few things I would appreciate it.
Gleening from the invoice of the radios mentioned by the OP , (apparently the "M" split), the high side injection for rx bears out a 10.7 mhz IF. The tx is derived by freq doubling.
So....
1- Is the 2nd mixer an MC3357/MC3361 or similar based design with a 455 khz disc stage?
2- Does the injection freq for the "HH" split unit rx revert to low side injection (10.7 mhz below desired rx freq?) (Midland's Syntech require a lowside injection kit modification)
3- Does the tx osc stay a doubler design or become a 3rd overtone design for the "HH"'s? (would make design/production sense, but then again we are talking about Motorola....lol)
4- What part of the M/N determines the split? (I'm fine to D(n)1TSA... but nada after that.)

I am curious because these (possibly the "HH") may work for a "mad scientist" 10/6 meter project I have in mind. Of course I'll have to spring for a SM if I persue this, but ATM I'm trying to cobble together a list of potential doners to the Franken-radio effort....lol

As the OP stated, not a lot of published info for these floating around the 'net. Any input from anyone would be greatly appreciated.

Denton is comming up this weekend and it would be nice to be better informed about these units when I get there.
tnx,
73
s.
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OOOOPS!

Postby swg » Wed Apr 14, 2010 6:18 pm

swg wrote:......
Denton is comming up this weekend and it would be nice to be better informed about these units when I get there.
tnx,
73
s.


OOOPS! No edit feature for moderated posts. That should be Belton, Tx (Spring Hamfest)
Dang oldtimers deezeez....lol
Now, what were we talkin about????
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Re: MAXAR 80 questions

Postby jackhackett » Thu Apr 15, 2010 7:40 am

Looks like a CA3089 based demodulator with no second IF, just the 10.7.
Receive appears to be low side injection for all splits, Fosc = Fc - 10.7
Transmit crystal freq is doubled in the M split, tripled in the H and HH splits.

And the model number gives no clue as to the split, just the number of channels, squelch type, and whether or not it has an extender.
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Re: MAXAR 80 questions

Postby swg » Thu Apr 15, 2010 4:30 pm

jackhackett wrote:Looks like a CA3089 based demodulator with no second IF, just the 10.7.
Receive appears to be low side injection for all splits, Fosc = Fc - 10.7
Transmit crystal freq is doubled in the M split, tripled in the H and HH splits.

And the model number gives no clue as to the split, just the number of channels, squelch type, and whether or not it has an extender.

Things that make ya go hmmmmm......lol
A long time ago somebody told me the Moxy was essentially an FM'd CB chassis, looks like this one doesnt even rate that with single conversion. Even the 49 mhz Maxon W/Ts had a 455 stage with a filter.....lol. Motorola MC33XX's in Midlands and Maxons, and Intersil's CA chips in a Motorola, go figure. Maybe it's true that M farmed out the deisgn/production of these low band dash mount unified chassis units to the "low band " dash mount unified chassis designs of the day ....aka CBs....lol. Doesnt take much rework to FM convert an AM rig and drive the PA to class C.
I read the rule on post of Fleabay links. I believe I'm covered since it is for reference, but I still tried to isolated the jpg only for reference. (I'll also code tag it to keep it "dead" too)
This is a pic of the invoice on the radios of the thread topic.
Code: Select all
http://i.ebayimg.com/18/!Bm0cJ2!CGk~$(KGrHqEH-EMEtqy4vs6OBLhClidp,g~~_3.JPG

If I'm reading this correctly, the rx crystal freq, Fosc is 10.7mhz above rx freq (Fc) and Fc being 31-32 mhz makes these at the low end of the low band spectrum, presumably "M" split.
interesting the SM doesnt account for that.
Even with the "HH" split being "low side" injection, the single conversion rx makes me shy away from using this series for my franken-radio. Perhaps with design spec for 20+khz spacing, add'l selectivity components were considered an unnecessary expense.
My research shows the LRA series Radius model # allows for one to determine the split, but the (nono-LRA series) Maxtracs do not. Apparently these follow that methodology.
Thanks for taking the time and effort to post the info Jack. It has been enlightening and very helpful.
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Re: MAXAR 80 questions

Postby mfdeng5 » Sun Apr 18, 2010 5:32 pm

I give up!!! It cant do what i want it to do...wrong split!!! Anyone want this? I got it from him on ebay for $45+shipping=$57.......Its new in the box!!!!
I will take $40 for it......
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Re: MAXAR 80 questions

Postby jackhackett » Mon Apr 19, 2010 7:33 am

swg wrote:A long time ago somebody told me the Moxy was essentially an FM'd CB chassis, looks like this one doesnt even rate that with single conversion.


The Moxy looks pretty close to the Maxar circuit, including being single conversion. Definitely not a modified CB chassis.
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Re: MAXAR 80 questions

Postby swg » Tue Apr 20, 2010 8:03 am

jackhackett wrote:
swg wrote:A long time ago somebody told me the Moxy was essentially an FM'd CB chassis, looks like this one doesnt even rate that with single conversion.


The Moxy looks pretty close to the Maxar circuit, including being single conversion. Definitely not a modified CB chassis.


LOL. Yeah, that was more of a poke at Moto for the engineering backslide compared to their previous philosophy of "over-engineering" everything. I think the only CBs from that era that were single conversion were those that processed ssb signals after the first injection. (AM usually went on to a 455 stage too)....not to mention frequency generation/systhisis design differences etc
I still run a DSR922 for my C Band sub and I try to kick them every chance I get for their tight control on DCII licensing, yet have no intrest in developing a "next-gen" IRD for consumer use.
We C Banders, especially the DCII subscribers have plenty of "Well if they wont die just kill them" mentality enemies as it is.....lol

Kevin - sorry to here about your failure to read the auction dilemma. I am sure that a lot of err.....umm.... people have done the same thing. Of course I have no personal experience with that, I mean, I'm just sayin'....lol
If you had only offered a 15-20 bucks take it or leave it, it wouldnt have stung so bad. I usually low-ball on "Best Offer" cause the seller either has no clue the true value (high or low) and/or will take just about anything offered for the item. Just like at the flea markets, you've got to be prepared to walk away......
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Re: MAXAR 80 questions

Postby Will » Tue Apr 20, 2010 12:45 pm

The Maxar 80 is much the same as the Maxar that it replaced in the '80s. With a few improvements one being higher transmitter power, the other a different power connector with larger pins for the battery input.

The Moxy was the less expensive Maxar with only one IF crystal filter stage.

I do have a low band Maxar 80 manual... somewhere!
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