Repairing the Maxar 80, need some help

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Repairing the Maxar 80, need some help

Postby jimhondo » Fri Dec 02, 2011 7:55 am

"hello..I am new here and I have a problem. I bought a place and there were a
BUNCH[16] of Maxar 80s here and I am trying to get them all running. I got
about 6 running fine, but the rest would start smoking on power up. The
SAME component is failing on all, and on checking the ones that work, it
looks like an orange drop capacitor with markings 47 and 25vdv best I can
determine.[very difficult to read because it's behind a little aluminum bar]
Looking down on the radio from the top the component is on the lower main board,
about an inch from the heatsink, diagonal from the speaker and very close to the
side chassis wall with a structural bar going over the top of it. There is a
small copper wire wound inductor right next to it. It is not a ceramic, but
looks to be a orange drop type...I am wondering also, what TYPE and the true
value of the component, so I can substitute.
Is this component failing because of age, or is something else making it burn
up?
I would like to fix these radios, but I don't have a schematic [someone
know where online?] and it's a bummer for me because I am in Honduras and
ebay is NOT an option...
Can anyone give me some direction regarding this?

Thanks Much
jim
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Re: Repairing the Maxar 80, need some help

Postby jackhackett » Mon Dec 05, 2011 1:46 pm

Sounds more like it may be a tantalum cap. Do a google image search for both tantalum and orange drop capacitors, see if it looks like on of those.

If you could tell us the model number of the radio it would help a lot.
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Re: Repairing the Maxar 80, need some help

Postby WB6NVH » Thu Dec 08, 2011 2:28 am

That should be a dip tantalum type and they fail by shorting out and burning up. They mainly do that when equipment which has been in storage a long time is powered up again. You would expect that from an electrolytic but these tantalums seem to be worse. I think you will want a 47 mf 25V as exact replacement although if they burned up, a 47 mf 35V will be longer-lived. Remember these have polarity and if installed backwards, there will be immediate smoke.

I replace hundreds of them a year. There seems to be no published information on why this happens or how to prevent it, other than replacing them with higher voltage versions. I have been pondering bringing up equipment slowly with a variable power supply to see if that re-conditions these capacitors, but it seems like when they want to go, they go regardless.

In the USA, these Maxar 80 radios, other than the low band ones, will be almost worthless doorstops in 12 months when narrowband becomes mandatory.
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Re: Repairing the Maxar 80, need some help

Postby jimhondo » Sat Dec 10, 2011 3:45 pm

Ok, sorry about the delay...I have been checking but saw lots of no responses and thought I was wasting time.
Thanks to both of you for your concern and help.
WB6NVH:
Regarding the caps....yes..I looked up orange drops and they are longer and narrower....so I will order some tantalums and take the chance, but I am sure you would know having worked on them. It's funny you mention bringing them up slow...I WOULD have, but I don't have a variable supply here...just a few 12vdc fixed types and car batteries...and YES, these were sitting around since 2005 from what I learned...and not the best environment...the tropics!..I am lucky they didn't have termites in them...as they seem to nest everywhere!
As far as the rules on narrowband...I am in Honduras and who knows...basically it's just me and a bunch of expat gringos who are going to use them...sort of a pirate radio club...strictly for emergency use if there is a hurricane or such...because things can get iffy in places like this and if the cell phones quit working[very possible] we would have a backup. I know that monitoring the radios for a couple of days...there was ZERO traffic...I mean...ZERO....I don't think anyone is even using the frequencies where we are...
As far as model and serial numbers...here they are:

3000CKD43TSA 475FMY1502
D43TSA3000CK 475FMY1501
D33TAS3300AK 240FD01004
D33TAS3300AK 240FD01010
D33TAS3300AK 240FD01005
D33TAS3300AK 475FFQ1716
D33TAS3300AK 240FD01003
D33TAS3300AK 475FFQ01709
D33TAS3300CK 475FXC0---numbers unreadable
D33TAS3300AK 240FD01007
D33TAS3300AK 240F---------numbers unreadable
D33TAS3300AK 240FD01013
D33TAS3300AK 240FEJ2609
D33TAS3300AK 240FDQ1008
D33TAS3300AK 240FD01011
D33TAS3300AK 475FF01708

I am still a bit puzzled about the actual frequency they operate at, but I am assuming
151 Mhz or thereabouts[ i have very little test gear here] but the mobile whip antennas, that were
with them are Motorola units for roof mount and are 17.5" from base to tip. It seems to me when I first got
here, the previous guy said 151 and I have been sticking to it. I know that they all talk to each other
on channel 1, both send and receive. We are cobbling up 3 base setups and the rest are mobile. I found 2 Ringo Rangers
here and 1 AEA Monopole...all I have adjusted for 151 Mhz according to the manuals I found online.
I have been trying to find out what the exact frequency IS, but after hours and hours of search on Maxars
I can't seem to determine it. I DID find the product codes saying they were the VHF band...so assuming
the antennas that were here, belonged to the batch...it has to be VHF and approximately 150 Mhz...I think.
Anything you can do to clarify that would help me tune my base antennas. One guy here says he has a field
strength meter, and and SWR meter, so I suppose the thing would be to tune the antennas that way...he
still has them packed and is trying to find them. [he is ex air force radio comms from the 60s and was part
of his base amateur club] One of the guys is some hot shot Canadian who has set up commercial radio all over
the world, so I am waiting for him to take a look too...and all these guys are coming on this pirate net so
there should be some brains...more than ME for sure..hahahah.
I also found 10 Maxtracs here as well, which also talk to the Maxars on Channel 1.
Right now, I have 15 operation units and a body for each of them, but I have the 10 maxar smokers
that I would like to repairs and get them to more guys in the group...So I will order the caps and have
then sent to me through my mail guy...I figure DigiKey should have the caps.

Thanks much guys and anything else you can suggest would be mightily appreciated!

Merry Christmas

Jim in Bananaland
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Re: Repairing the Maxar 80, need some help

Postby jimhondo » Sat Dec 10, 2011 3:58 pm

Oh..one other thing...the caps...

I am going to order THIS cap....do you think it is the correct choice?

http://search.digikey.com/us/en/product ... -ND/564017

I hate to spend 60 bucks and have the wrong cap...hahahah

thanks!

Jim
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Re: Repairing the Maxar 80, need some help

Postby jackhackett » Sun Dec 11, 2011 9:09 am

Assuming we've got the value correct that should work. I can try to find which cap it is the service manual now that I have the model numbers just to be sure, but I won't have access to those until Monday.

If you want to go with something a bit less expensive you might try this one:

http://www.jameco.com/webapp/wcs/stores ... CID=pdfSKU

it's 25v instead of 35v, but that's what the original one was anyway, and I don't think you're going to gain much by going with the higher voltage... either should last longer than you'll use the radios, so a couple extra years life on a cap won't matter.

Of course you'll also have to look at shipping costs, I don't know how much difference there is between Mouser and Jameco for international orders.
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Re: Repairing the Maxar 80, need some help

Postby WB6NVH » Sun Dec 11, 2011 2:53 pm

Yeah, same deal here, I can't verify that value without pulling the manual and I don't know where it is at the moment. The highest voltage any component sees inside that radio is approx. 13 Volts or whatever DC you are running it from. The 25 Volt version will work for you as long as you will likely have the radios. The idea of the 35 Volt rating is part of a theory that the higher the rating, the less likely they are to burn up someday, but I haven't seen anything in print saying this. Technically 25V should be more than enough, but you can see that whatever happens in storage negates this theory. I can't say that a 35V wouldn't have burned up as well. This failure mode is not well understood at the moment.

Tantalum capacitors are quite expensive now due to some materials shortage issues. If I were doing it I would just get the 25 Volt ones. You may actually find that the radio will function just fine without it. I can't recall why it's used but I think it's just a filter on one of the power feed rails.

You may be able to calculate the operating channel by looking at the crystals but you will need know which one is the transmitter crystal and then multiply the frequency on it by whatever the multiple is for that radio. Motorola seemed to avoid stamping the operating frequency on their crystals but International and Sentry (aftermarket) usually did. Those are high band radios so it's probably something between about 150-160, more or less.
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Re: Repairing the Maxar 80, need some help

Postby k2hz » Sun Dec 11, 2011 3:25 pm

I have the manual in front of me and I think I found the part in question:

c168 23-84538G06 47uF +/- 20% 20V

It is on the line from the collector of Power Control Driver Q 802 to the output of the Exciter Power Amp through L124. The collector of the Amp Q122 goes through L123 to the junction of L123, L124 and C163 with the other side of C163 being the output to the PA.
Last edited by k2hz on Sun Dec 11, 2011 4:22 pm, edited 1 time in total.
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Re: Repairing the Maxar 80, need some help

Postby Will » Sun Dec 11, 2011 3:57 pm

jimhondo wrote:Oh..one other thing...the caps...

I am going to order THIS cap....do you think it is the correct choice?

http://search.digikey.com/us/en/product ... -ND/564017

I hate to spend 60 bucks and have the wrong cap...hahahah

thanks!

Jim


A good electrolytic capacitor should work fine, and save you a lot of money too....
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Re: Repairing the Maxar 80, need some help

Postby jimhondo » Sun Dec 11, 2011 5:41 pm

Wow..you guys have be great in helping me out and I will wait till you get that manual jackhacket. I have a little window here[about a week] before I order anything. Shipping cost isn't too bad because I have it sent to a pal in the states and he remails it for me with other stuff I need from up there...so it works out cheap..just takes weeks to get here. I think I WILL get the cheaper cap...at 25volts because the whole issue is...they are old radios and I already have a couple weeks of time checking them, making up mobile whips, and basically entire kits for the guys to install with...and I will be helping with most of the installs because some of the guys are all thumbs...grin...
The guy I mentioned earlier, who was the air force tech volunteered today to do the repairs, so that took some load off me on this project. But I still need to get him the caps.
The primary thing I am concerned about is the polarity, unless I tear one of the good ones apart..and believe me...that sucker is buried way down in there...the only way we could read it was enlisting a young local guy with good eyes...hahaha...us old geezers couldn't even read it...but with some verification I will order.
I am going to try to photograph the thing or it's location...but I lost my camera software to a lightning strike on my puter and haven't reloaded it yet, but if there is any confusion or questions, I will take a pic. Please ask for details if there is a question.
I tell you guys...you never really appreciate how easy it is to do something in the USA, until you live in some 3rd world deal like this...they have SOME stuff...and sometimes stuff you wouldn't think they would have, but overall, it's a major pain to get anything done past cement, rebar and angle iron. What is TRULY amazing though, is that sometimes you find stuff so cheap you can't believe it. For instance...I lost my stereo speakers to a line surge[frequent] and I ended up having to replace a total of NINE speakers...ya know..tweeters, mid range, woofers etc....I replaced ALL of them, for 46 bucks...and the stuff sounds great and has a higher power rating....crazy!...BTW...I have line conditioners on EVERYTHING now...even my refrigerator....because you drop outs, surges, complete outages...I mean...ALL THE TIME...so it's tough on everything. And I am about a quarter mile from the ocean, so everything rusts...IMMEDIATELY...
Overall, it's a LOT cheaper to live, and I come from Wisconsin originally, so I don't miss the snow and high taxes...but it sure is a paradigm shift living here...pheww..
Anyway...Thanks again guys...you are saving my butt on this situation and I truly appreciate it!

Jim in Honduras...murder capital of the Western Hemisphere{seriously :/]
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Re: Repairing the Maxar 80, need some help

Postby jackhackett » Mon Dec 12, 2011 10:17 am

Yeah, looks like k2hz has it, C168. Go ahead and order, good luck with your project.
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Re: Repairing the Maxar 80, need some help

Postby CircleBat » Mon Dec 12, 2011 10:36 am

it will be cheaper to pickup a motorola maxtrac than ordering the caps... Spend the money on a used radio instead...Those Maxar 80's are just not worth repairing and are problematic radios!!!
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Re: Repairing the Maxar 80, need some help

Postby jimhondo » Mon Dec 12, 2011 3:33 pm

Jackhackett...ok..will do...thanks Much!

Circlebat...I have 9 Maxtracs already, but I have like 10 repairable Maxars...and 6 working ones...and I live in Honduras, I may be able to BUY them cheap THERE, but shipping would be insane...besides, one of the guy's in the net wants to repair them..so..a few bucks for the caps and maybe we can get some going...the ones that work now seem ok....this is a very low budget situation and we are doing this for fun...the whole idea is just about hooking up some of the guys in case we have an emergency here...and right now I have 2 spare maxtracs, but the network may expand past 15 guys and if it gets really serious, I will let them buy their own radios...right now...I am just passing these out for free and one guy has the smarts to fix them...so it's just a fun thing...shrug...
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Re: Repairing the Maxar 80, need some help

Postby CircleBat » Tue Dec 13, 2011 1:12 am

what frequency is this maxtrac? might have a service manual here still before it hits the recycling bin

Circlebat...
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Re: Repairing the Maxar 80, need some help

Postby jimhondo » Sun Dec 18, 2011 2:04 pm

Circlebat..sorry about the delay...busy with other work.
I am not sure exactly, but they talk to the Maxars and I think they are 151Mhz...
The model number code says the "middle" frequencies, which are apparently 136- to 174 Mhz

That helps any?
Jim
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Re: Repairing the Maxar 80, need some help

Postby k2hz » Mon Dec 19, 2011 7:16 am

jimhondo wrote:Circlebat..sorry about the delay...busy with other work.
I am not sure exactly, but they talk to the Maxars and I think they are 151Mhz...
The model number code says the "middle" frequencies, which are apparently 136- to 174 Mhz

That helps any?
Jim

The manual for the D33TSA3300 is 68P81037E95 "MAXAR-80 Two-Way FM Radio 136-174 MHz"

Have you looked at the frequency of the crystals to see what frequency they are on?
If they are not all on the same frequency or they are different Tx/RX frequencies you have a problem given the cost of new crystals and the need to realign the radio if the frequency is changed more that a few MHz.

If the channel frequency is not marked the crystal formulas are:

RX = (F-10.7)/3 TX= F/9
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Re: Repairing the Maxar 80, need some help

Postby jimhondo » Tue Dec 20, 2011 7:00 pm

K2HZ...We are ok with frequency..in that the radios all talk to each other just fine...apparently they all came from one fleet or public service. I tested them all and they all talked to each other just fine....I just wanted to know because I wanted to make some dipoles for them.
The latest news on this project, is that we have just started our "real life" tests. I mounted an AEA Monopole on the top of my shop here, at about 20 feet above the ground, and my buddy in the net put up a Ringo that was here, plus he set up one in his truck. He is about 2-3 miles down the road and the signal is PERFECT...honestly..better than most cell phones. And today, he went into the nearest town about 4-5 miles away from my Monopole, and him mobile with the 18" whip mounted on his truck rack. Again...great signal and clarity....so the system is starting out well. As the weeks progress, we should be getting more guys on board across a larger area, so it will be interesting to see what results we get..so far so good though.
The first units in this test were the Maxtracs, so we haven't tried the Maxars in real life, other than the bench tests to determine if they work and work together. The ones that smoked will be repaired after the new year as soon as my partner on the net gets the parts.
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Re: Repairing the Maxar 80, need some help

Postby kcbooboo » Tue May 08, 2012 11:52 am

Just a quick addition to this post.

I acquired three VHF (150.8-162 MHz) 55w Maxar-80 radios. One worked fine. One had low TX output and poor sensitivity. One received fine but was drawing over 2 amps all the time, would not transmit, and a power transistor in the front right corner got hot enough to burn me. I bought a manual; an absolute necessity.

The one with low TX output and poor sensitivity also had a damaged UHF connector. I removed the PA circuit board and the connector, straightened everything else, reassembled it, and tweaked the PA tuning and the front-end tuning. That got the radio back to spec.

The one drawing over 2 amps had a shorted C168: 47uF 25V tantalum (orange) capacitor. As noted, it's in an impossible spot to get to: under a front end mounting boss. I tried removing the front end; no go. I ended up removing the main board from the chassis, which is a lot of work. Unsoldering the old cap was easy; getting to it was the hard part. I replaced the cap (which measured 0.0 ohms) with a 47uF 25V aluminum electrolytic, bent towards the front of the radio so it would clear that front end mounting boss, put everything back together, tuned the PA, and the radio is now making 55 watts. All of this took me 2 hours, most of which was spent trying to get the main board unsoldered from the chassis.

As Murphy's Law states: the part that's in the hardest spot to get to, is the one that will need to be replaced. It was.

Bob M.
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Re: Repairing the Maxar 80, need some help

Postby Will » Tue May 08, 2012 3:12 pm

Bob,

Now you know what we went thru back when these were new and for years afterwords repairing them. But they worked well.

Did not have programmable radios then.
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Re: Repairing the Maxar 80, need some help

Postby kcbooboo » Wed May 09, 2012 4:12 am

The Maxar was just another case of a radio that was never intended to be repaired, or at least the designers never had to see what was involved in getting to all those parts. I've built dozens of Heathkits and all were easier to work on than this radio. Six pounds of crap in a five pound box. What a P.I.T.A. Even after getting the board unsoldered from the chassis, it still only moved about 1/2 inch. I wonder what kinds of laborers they used to assemble them. At least all the parts are BIG; no SMD stuff.

The ones I have work surprisingly well. Sensitivity is around 0.4uV for no crackles (about 20dB quieting) and they go right up to 55 watts as rated, but the PA gets hot very fast. Certainly a lot less heat-sinking than in a MaxTrac. Unfortunately they only cover 150.8 to 162 MHz so I can't move them into the ham-band nor up to the weather channels, although they'll probably receive weather if I pushed them there. And with narrow-banding, they'll become cheap paper weights by the end of the year.

Bob M.
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Re: Repairing the Maxar 80, need some help

Postby RFguy » Wed May 09, 2012 5:57 am

The Maxar 80 was a great radio. The last good radio with a decent front end. The helical resonator made it a good radio for RF congested areas. I remember the first few time we put in the brand new Maxtrac 300’s in place of the Maxar 80’s. Customers complained of range loss. Turned out the lack of selectivity of the Maxtrac's resulted in increased desense.

I know a few Hams using Maxar and Maxar 80's as packet radios at solar powered sites. They have very low standby current.
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Re: Repairing the Maxar 80, need some help

Postby kcbooboo » Wed May 09, 2012 2:45 pm

Yes, I noticed the low standby current, especially with non-functioning pilot lamps (which shall be fixed later tonight). As only a handful of transistors are used in the receiver, it's a gutless wonder, but the tight front end is probably as good as what you'd find in a Micor. The lack of a microprocessor and synthesizer also contribute to the low input current. Any radio with a tuned front end will outperform a MaxTrac, but you trade the labor required to tune everything for the wide-band operation of the MaxTrac.

Bob M.
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Re: Repairing the Maxar 80, need some help

Postby KitN1MCC » Wed May 09, 2012 5:20 pm

bob what freq you gonna put it on
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Re: Repairing the Maxar 80, need some help

Postby kcbooboo » Thu May 10, 2012 1:51 am

Since the radios won't go into the ham-band or up to the weather freqs, I have absolutely no use for these radios. All are 55 watt, single freq (but have two-freq main boards), with DPL squelch. Currently on 150.860 MHz. All have bent/mis-shaped UHF connectors but they're still functional; they just aren't completely round. The three hand mikes are in horrible shape and need new cables and connectors.

They're yours for a great price: the amount it cost me to fix them up (so far, $12)!

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