MT1000 Low Band

[Stage 2]

I am looking for a second opinion. I am working with Low Band 42-50 Mhz MT1000's. While I can put any 6 meter freq. in, it appears that anything above 53 Mhz without the Mods described on the Repeater builder site to the VCO module cause the radio to not operate on channels with those frequencies even if it is just the RX side. Conversely , any channels where both RX/TX freq's are below 53 Mhz, the radio seems to work normally with no mods to the board. Is my experience typical? Also, can anyone tell me how much performance is affected in the apparently safe(un modified VCO) below 53 Mhz range. I did test an one of these against a 2 Meter MT1000 with a wideband antenna meaning 2 Meter Simplex versus 6 Meter simplex and both radios pretty much had the same range on Duck antennas inside a vehicle talking back to the same stationary base. Just looking for some input. Thanks

[PETNRDX]

Not sure I really understand the question.
But, I have had several of these low band radios, and some will go up to 53 mhz or so, and many won't even go that high.
Either the radio goes there or it won't.
Doesn't seem to have hurt the radios that I have used. Some longer than 20 years.
Range from inside a vehicle should be less on 6 meters just due to the antenna "efficiency".
But, get outside standing in the open should be pretty similar.
I would say that I have found more of the P200's that work OK higher up at 6 meters than the MT1000.
Don't know why though.
If the mod you are talking about is the one where you change several surface mount parts, I have not done the complete mod.
I have had the VCO out, and it is difficult.
Probably have about 8 of the radios right now, and about half will not work at 52.8 mhz.
I suppose I really should buy the parts from that article and try it on the ones what won't work.

[mike m]

as I mentioned at the end of my repeater builder document, I worked on a couple of radios that did not need any VCO mods and others that required full vco mods.

Since I no longer have the radios which were used for that document I failed to check revision numbers on the radios and the vco's; however, some were P200 low band while others were MT1000 6 and 99 channel and from what I remember the 99 channel MT1000's all tuned to ~53.3 without VCO mods while all P200LB's and all 6 channel MT1k's required full VCO mods.

Take your time and do the mods, you'll be happy with it. This past Tuesday I had BV2DQ in Taipei Taiwan on my 10 meter MT1000 from NORTHERN OREGON USING THE 11 INCH RUBBER DUCK.

It took my base radio with 60 watts on 29.6 simplex along with a hop over to our local portland, 29.68, repeater to complete a valid 2-way contact but still to hear China DFQ on a FM ht was fun.

Mike/ VLC

[Stage 2]

Thanks for the response, guys. Mike, Digikey is saying the capacitors are obsolete. Part target did have them but, wanted a minimum order of 10 pieces @ $85.00 each. Do you know where I can find these, or, a replacement for them without spending a small fortune?

Thanks,
Shaun

[mike m]

interesting on digikey, i'll check mouser but as long as you aren't operating over wide temperature extremes, +70 to -55C, I'd think any chip cap in the correct case size will work.

[mike m]

ok just checked digikey, looks like the 1276-1307-1-ND will work, it is 8.2 pF but it should be fine for C1.

For C2 the digikey 712-1380-1-ND or the -6-ND will work.

I need to revise the original document to say that any comparable NPO chip cap in a 0805 case with a capacitance between 6.8 to 9.1 pF for C1 and the same specs between 15 to 20 pF for C2 will work.

[Stage 2]

Awesome Mike. Thanks a lot. I will check those Capacitors out @ Digikey. All the way to Taiwan on an MT with a rubber duck! Wow! It doesn't matter that you got the bump from a repeater in my book. Hearing stuff like that just makes you want to do the work. Yeah, you could buy a 6 meter rig, but, I would rather have something different and, stay with the brand that this site is all about.
Regards,
Shaun

[mike m]

a few days after taiwan on the Portland repeater I had a kl7 in fairbanks alaska and zl2ok in Hastings New Zealand on 29.6 simplex with the 10 meter ht and then some 6 meter repeaters in Arizona with the 6 meter cousin a few days ago.

Most interesting is I have about 35 states on the 6 meter ht, many are duplicates over years, and ~ 15 states and several dx countries on the 10 meter model. Certainly less total contacts with my 10 meter model but longer distances on the 10 meter model also.

[PETNRDX]

That is pretty cool.
A friend and I just got back from doing P25 coverage mapping for the NPS in Yosemite.
I used a P200 on 52.525 and he used his Maxtrac with a cowl mount.
We had pretty good coordination with just that setup.
Who says low band is dead...

[mike m]

yep low band, especially 6 meters is alive and well judging by the record breaking east coast to Africa opening today on 6 meter ssb and cw, 6 meters especially is doing very well.

I just wish it would open up more up here in the Northwest US, it's depressing to see 10000 mile spots with hams using medium sized antennas into the South Atlantic and Central Africa all the time having only static in this part of the country.

[PETNRDX]

Yeah, I lived in Seattle for 50 years.
Was on 6M from abt 1975 til I left in 2004.
You are right, band openings pretty rare up there.
I did work Argentina late 70's tho.
I think I need to find an MT1000 or P200 for 10 to play with.
Got an old IC502 at SeaPac last year, but it has TX audio distortion BAD.

[mike m]

I may have to cheat and put up a 6 meter cw/ssb remote radio at my Arizona QTH at 5700 feet elevation with a 6 or 7 element stack.

With a cheap PC/UPS and basic Internet setup this may be what it takes to quench my 6 meter thirst.

10 meter mt1k/p200 splits are tough to find, I converted a mid split MT1k, 36-42 MHz, to 10 FM but it was a lot of parts changes to get it on 10FM.

Somewhere on the p25.ca group I have the conversion info.

[Stage 2]

Hi Mike and all. Finally after several months I had the time to take apart my 6 meter MT1000. When I read the article I missed the part about having to de-solder a second set of pins. Its a good thing I did because I would probably not have tried to do the mod. I made a mistake by de-soldering the wrong end of the second set of pins, but, it was not a problem as I was still able to get to the 2 capacitors and do the swap. Talk about tight soldering with tiny pieces! Yikes! Anyway, it was when I was reassembling the radio that I found my second problem. I hadn't noticed that one of the first set of 11 pins connecting to the main board had broken off. Frustrated after working for several hours at that point, I put all the parts of the disassembled radio into a Ziploc bag until today. Not wanting to give up, I guessed that I could make another "pin" out of a piece of small diameter speaker wire. It was a royal pain to solder this to the VCO board which was simply lying on my desk as I don't have any sort of holding device and just an ordinary 15 watt soldering pencil. My patience paid off though. After carefully soldering on end of the speaker wire and bending it to resemble the other pins next to it, I managed to guide it along with the other pins back into their places. After soldering the pins back to the main board and reassembling the rest of the radio, I reattached the battery. Finally, I closed my eyes, crossed my fingers and powered the radio up. Much to my relief, on a local 53MHz repeater where the processor wouldn't make a sound before the surgery, much to my delight it beeped normally. I tried this on all 6 channels as it would only do it on one that was below 53MHz before. It worked flawlessly on all 6. I got feedback from a local ham buddy who told me the radio has great booming audio. An adventure to be sure, Mike, but it was worth it. Now I know what you mean, and, even better, I have another Ham band to use while staying loyal to Motorola. I thought you, and others thinking about it might like to hear my story. It was certainly a learning adventure, but, well worth it.

73,
Shaun

[HTQ]

I may have to cheat and put up a 6 meter cw/ssb remote radio at my Arizona QTH at 5700 feet elevation with a 6 or 7 element stack.

With a cheap PC/UPS and basic Internet setup this may be what it takes to quench my 6 meter thirst.

10 meter mt1k/p200 splits are tough to find, I converted a mid split MT1k, 36-42 MHz, to 10 FM but it was a lot of parts changes to get it on 10FM.

Somewhere on the p25.ca group I have the conversion info.

Have any one had any luck on 6 meter FM with the Motorola MT1000 I was able to program up to 53.14 MHZ, and if so what antenna was used.

[PETNRDX]

Not sure what you mean by luck.
I have several P200's and a couple of MT1000's in use.
We run a pair of linked 6 meter repeaters at around 8000 ft, adding voted receivers to them right now.
I use the factory Motorola heliflex cut to 6 1/2 inches not counting the cap or the threads for center around 52.525.

[Stage 2]

Hi Mike. It's been a while since I did the conversion and also since I touched base with you on the results. I will try to cover everything that has happened since doing it. When I first tired looking up the Panasonic part numbers in your article at Digikey, I was unsuccessful as the part numbers were obsolete. After writing you explaining that I was not familiar with what I was looking for let alone what parameters I should look for, you kindly went to Digikey and gave me part numbers for both C1 ( 1276-1307-1-ND, 8.2 Pf ) and C2 ( 712-1380-1-ND, 18 Pf ). I ordered and installed them and then programmed the radio with the modified RSS.

Both good news and bad news here. The radio is awesome to about 53.500 Mhz. I say this as there is a repeater in my area that has 53.450 as one side of its split. My radio takes this, but, when I tried 53.500 Mhz, the vco locked and wouldn't accept it. You did tell me in a PM that based on a QTH @ 53.99 that C1 could drop to 4.7 to 5.2 Pf and C2 could go from 10 to 12 Pf. After getting the hang of Digikey's search parameters, I did locate 5 Pf ( 1276-2552-6-ND ) for C1 and 10 Pf ( 1276-2561-1-ND ) for C2. I did not get around to ordering them though.

Here is where it gets interesting. I decided to revisit your article as like most folks sometimes the next time around you pick up stuff you missed the first time through. There it was right in plain sight listed under parts needed. You clearly state that "Data taken after several conversions that C1= 7.5 Pf and C2= 16 Pf is perfect to cover the entire band".

I went back to Digikey and found the following for C1 # 712-1374-1-ND 7.5 Pf and for C2 # 399-8775-1-ND 16Pf. I think I used the correct parameters and, would like to try these. Mike, would you please take a look at these to confirm that I wouldn't be putting something into my radios that would brick them?

I hope that I didn't rattle on too long, but, wanted to include our discussion on this fun project for all to enjoy.

Thanks, Shaun