Does anyone have an inside picture of the messenger 800 or a schematic for it. I have one that I would like to put back in original condition.
Thanks
Kruser
Thanks
Kruser
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Messenger 800 help
- Thread starter Kruser
- Start date
This question has been here a while without being addressed.
I don't have a picture from which you can follow but, there are Messenger Amplifier roadmaps on the CB Tricks web site; the amps are all built on the same principles, if you understand SS amps then you can apply what you need to your amplifier.
The 2 KW Solid State Messenger was nothing more than two 1 KW amps married together.
Take pictures of your amplifier and post them so that we can see what you have and, where your questions are, there are a lot of people here who can help you, is the amp dead?
.
Toll_Free
Well-Known Member
What exactly are you wanting to know... I have an M2000, an M1200, and a M4V that someone tried to convert to 2879s.
The m4v will NOT stand up to being converted, ESPECIALLY if it had the MRF455s in it in the first place. ENSURE you have an M800 (2290s) or M1200 (2879s) FIRST.... I got into an argument on CBTricks forum with someone connected to Messenger. I informed him he was full of crap. He argued. I took a picture of the damage to the inside of the converted 4V. The main output combiner was SMOKED, had cracked and heated SO bad it started the insulation on the wire in the combiner on fire. Fire spread to the rest of the amp. I have pix of it I can send ya if ya want...... BUT, it sure did make a MESS of a nice amp.
Oh, after pix where sent, he actually asked Sam about the 4V being converted. Sam agreed. The M4V, M800, M1200 and M2000 COMBINERS ARE ALL DIFFERENT!!!! The 455 / DS1446 / SRF3775 combiners are all designed for 600 watts PEP output. When you go up 1.5 times, they JUST can't handle it, the mix isn't correct for the flux density you have... CRACKAGE is the result.
CBTricks doesn't have ANYTHING newer than the 4V I could find. If you do need parts values for a Messenger, lemme know. I have a few of the originals around....
For the most part, the Texas Star line of amplifiers are pretty close. I've used their schematics when I've had to work on a "basic' amplifier, or one I don't have schematics for... They are BASIC amplifiers, and if you can't make it go with a TS schematic, ya got problems elsewhere...
ALSO, the BIGGEST problem Messenger amplifiers have (or the biggest plus, depending on who or how you ask) is the bias network. They run LOTS of bias, most have 1 volt or more. Makes for LOTS of CLEAN power, but REALLY inefficient amplifiers. I've modified ALL my 2879 and 2290 based amplifiers for .72 to .75 volts on the bases, and ALL are as clean as stock, a bit more efficient (which matters when you have 14+ 20 amp devices in your amplifier!)... Drive power goes up slightly, but I do NOT run ANY drivers in ANY of my amplifiers. They are ALL just straight amps, the Messengers ALL have drive sections pulled out. With the gain they have, it just INVITES oscillations!
--Toll_Free
The m4v will NOT stand up to being converted, ESPECIALLY if it had the MRF455s in it in the first place. ENSURE you have an M800 (2290s) or M1200 (2879s) FIRST.... I got into an argument on CBTricks forum with someone connected to Messenger. I informed him he was full of crap. He argued. I took a picture of the damage to the inside of the converted 4V. The main output combiner was SMOKED, had cracked and heated SO bad it started the insulation on the wire in the combiner on fire. Fire spread to the rest of the amp. I have pix of it I can send ya if ya want...... BUT, it sure did make a MESS of a nice amp.
Oh, after pix where sent, he actually asked Sam about the 4V being converted. Sam agreed. The M4V, M800, M1200 and M2000 COMBINERS ARE ALL DIFFERENT!!!! The 455 / DS1446 / SRF3775 combiners are all designed for 600 watts PEP output. When you go up 1.5 times, they JUST can't handle it, the mix isn't correct for the flux density you have... CRACKAGE is the result.
CBTricks doesn't have ANYTHING newer than the 4V I could find. If you do need parts values for a Messenger, lemme know. I have a few of the originals around....
For the most part, the Texas Star line of amplifiers are pretty close. I've used their schematics when I've had to work on a "basic' amplifier, or one I don't have schematics for... They are BASIC amplifiers, and if you can't make it go with a TS schematic, ya got problems elsewhere...
ALSO, the BIGGEST problem Messenger amplifiers have (or the biggest plus, depending on who or how you ask) is the bias network. They run LOTS of bias, most have 1 volt or more. Makes for LOTS of CLEAN power, but REALLY inefficient amplifiers. I've modified ALL my 2879 and 2290 based amplifiers for .72 to .75 volts on the bases, and ALL are as clean as stock, a bit more efficient (which matters when you have 14+ 20 amp devices in your amplifier!)... Drive power goes up slightly, but I do NOT run ANY drivers in ANY of my amplifiers. They are ALL just straight amps, the Messengers ALL have drive sections pulled out. With the gain they have, it just INVITES oscillations!
--Toll_Free
Well i can take pictures of my m400 which is basically half of the m800 if you want.
And Toll_Free, you just answered a few of my questions, and saved me some heart ache and pain.
thanks
And Toll_Free, you just answered a few of my questions, and saved me some heart ache and pain.
thanks
I dont understand it when people think they can just swap a lower power transistor with a big one because it fits in the old ones spot! Then they figur that was easy! Then figure thats all they need to do or worry about then poof goes a nice amplifier which those Messengers are very nice amplifers.
Toll_Free
Well-Known Member
Wile: The m800 IS NOT a pair of 4Vs... That was the M8V, and I don't think that ever went really to market. It was the M2000 boards, with MRF454s in it. Before Toshiba came out with theirs. My M2000 started out as a M8V, and one day Victor called up and said bring it down, I got an upgrade.
We went from 1400 watts to 2400++ in about 2 hours. Same cases, different boards. All where ready to go.
Tony: Most people got that idea because of RF Parts, I believe. For awhile in the 80s and early to mid 90s, while Motorola was getting OUT of the 12 volt and HF game, RF Parts saw the writing on the wall. They bought EVERY "double dot black cap" MRF device they could and rebranded them SRF devices. Yes, they put out about 10-25 percent more power... ESPECIALLY when you replaced the MRF455 with the SRF device... My Texas Star and Messenger 1 pill mod boxes went from 50 PEP to 75 PEP, NO changes other than the pill.
Well, that voodoo is behind us now. RF Parts snapped up everything, and they have the cache. Mot isn't really making 12 volt or HF bipolars now, they went to FETS when they got M/A COMM. Can't say I blame them, LOTS more profit margin in FETS vs bipolars! They blow more, too!
I miss the days of a single pill upgrade... Not having to rewind a transformer, throw an ARCO trimmer in, peak the circuit, pull the ARCO out, LC meter it, solder in the real RF rated cap, etc.
--Toll_Free
We went from 1400 watts to 2400++ in about 2 hours. Same cases, different boards. All where ready to go.
Tony: Most people got that idea because of RF Parts, I believe. For awhile in the 80s and early to mid 90s, while Motorola was getting OUT of the 12 volt and HF game, RF Parts saw the writing on the wall. They bought EVERY "double dot black cap" MRF device they could and rebranded them SRF devices. Yes, they put out about 10-25 percent more power... ESPECIALLY when you replaced the MRF455 with the SRF device... My Texas Star and Messenger 1 pill mod boxes went from 50 PEP to 75 PEP, NO changes other than the pill.
Well, that voodoo is behind us now. RF Parts snapped up everything, and they have the cache. Mot isn't really making 12 volt or HF bipolars now, they went to FETS when they got M/A COMM. Can't say I blame them, LOTS more profit margin in FETS vs bipolars! They blow more, too!
I miss the days of a single pill upgrade... Not having to rewind a transformer, throw an ARCO trimmer in, peak the circuit, pull the ARCO out, LC meter it, solder in the real RF rated cap, etc.
--Toll_Free
Toll Free, if I understand you right, you say the M800 should have the 2290 pills installed: is that right? This one has all 2879s. That is kind of why I wanted to see a picture of the inside to see if someone might have changed things around. This amp was working fine at one time then just quit putting out anything. It is just like someone put a wedding ring on the darn thing. (That might make a good signature: if your amp stops working, check to see if someone put a wedding ring on it so it would quit putting out). All the pills are good and I haven't found anything along the RF chain that appears to be broken or bad. The relays checked out on the ohm meter but I suppose that does not mean they will pass RF.
I did enjoy your information about RF Parts buying up the transistor cache. It explains what they told me about Motorola custom making transistors just for them. I have purchased a voocoo bunch of stuff from RF Parts in the past but lately their order department has went to H E double L. They never get my order right and then I have to pay to send it back and then wait two more weeks for the right part (hopefully) to arrive. Twice they have told me their employees have not shown up for work and there would be a delay. Then when I turn on the TV I hear about all the people out of work!! I have lost a couple of good customers because of them.
Back to the amp again. I had the same experience of a 500V Texas Star just having a heart attack and dying for no apparent reason. I went through it checking every component and found nothing bad. There was nothing left except the coax jumpers and I had already checked around the ends for melted insulation or stray wires. When I did an ohms check on one of them I found it was shorted. An autopsy revealed the short was mid-way between the ends from what looked like a flaw in the shield from the factory. I suppose the heat from using the amp was enough to allow the shield and center conductor to get together. I bet no one else has had that to happen.
I think I will just make a pot of coffee, lock the door and set down with the thing and use some brain power (hope I don't burn out my final) and see what I can find. The 800 has a small relay off the board that I can't remember right off what it does. That might be a place to start looking. I hope I am not just....:bdh:
Kruser
I did enjoy your information about RF Parts buying up the transistor cache. It explains what they told me about Motorola custom making transistors just for them. I have purchased a voocoo bunch of stuff from RF Parts in the past but lately their order department has went to H E double L. They never get my order right and then I have to pay to send it back and then wait two more weeks for the right part (hopefully) to arrive. Twice they have told me their employees have not shown up for work and there would be a delay. Then when I turn on the TV I hear about all the people out of work!! I have lost a couple of good customers because of them.
Back to the amp again. I had the same experience of a 500V Texas Star just having a heart attack and dying for no apparent reason. I went through it checking every component and found nothing bad. There was nothing left except the coax jumpers and I had already checked around the ends for melted insulation or stray wires. When I did an ohms check on one of them I found it was shorted. An autopsy revealed the short was mid-way between the ends from what looked like a flaw in the shield from the factory. I suppose the heat from using the amp was enough to allow the shield and center conductor to get together. I bet no one else has had that to happen.
I think I will just make a pot of coffee, lock the door and set down with the thing and use some brain power (hope I don't burn out my final) and see what I can find. The 800 has a small relay off the board that I can't remember right off what it does. That might be a place to start looking. I hope I am not just....:bdh:
Kruser
Toll_Free
Well-Known Member
Yup. The 800 is a 1200 with smaller transistors. Think it was ORIGINALLY designed around the MRF454... I STILL have a pair of boards with the 454s in them from a 16 pill amp 
The 1200 is the M2000, cut in half and using the basic board assy from the 4v, rather than the boards from the M2000. The earlier M800 and M1600 (which never really made it to production, I believe 6 to 10 where made of the M16, and they where ALL sold in San Diego to locals, at least that I know of. The FIRST M16 became the first M2000, and it's sitting 5 feet away, hence the reason I've got the M16 boards)
The small relay off to the side, so to speak, is for bias. Messenger uses a seperate relay to control the bias, as its MUCH MO BETTAH to ground the base of the transistors when you're NOT keyed up.... Reduces the chance of oscillation when the load is removed from the collectors (the relay unkeys), and reduces the change of 'white noise' being produced (another fancy name of a different type of oscillation, this one being broadband in nature) that you hear on receive.
I <<BELIEVE>> you're OK with the 2879 conversion. The problem with the M4V being converted to 2879s is with the output combiners. If you have ANY VSWR, you'll smoke them. I have a 4V that literally caught on fire after being converted. I've spoken with Sam about it indirectly (CB Doctor BDW argued with me on CB Tricks about this NOT being the case.... about 4 days later he confirmed that Sam concurred with my statements.... Stand up individual for admitting he was wrong like that, all other personal bullshit aside). The 2290 and 2879 boards differ only in the input and output xformer capacitors I think..... Anyway, for 2879s, 5 turns on the output with 1200 pf across it will get you 1200 watts or better The resistors in the hi / mid / low probably need to be changed to corrolate to the slightly different input impedance (if you want the ratios to remain the same.... I use high power, anything else is nothing but an SWR issue)
Lemme know how it goes.... Sounds like a good project, and sounds like bad xister in the drive section, or maybe a bad cap....
--Toll_Free
The 1200 is the M2000, cut in half and using the basic board assy from the 4v, rather than the boards from the M2000. The earlier M800 and M1600 (which never really made it to production, I believe 6 to 10 where made of the M16, and they where ALL sold in San Diego to locals, at least that I know of. The FIRST M16 became the first M2000, and it's sitting 5 feet away, hence the reason I've got the M16 boards)The small relay off to the side, so to speak, is for bias. Messenger uses a seperate relay to control the bias, as its MUCH MO BETTAH to ground the base of the transistors when you're NOT keyed up.... Reduces the chance of oscillation when the load is removed from the collectors (the relay unkeys), and reduces the change of 'white noise' being produced (another fancy name of a different type of oscillation, this one being broadband in nature) that you hear on receive.
I <<BELIEVE>> you're OK with the 2879 conversion. The problem with the M4V being converted to 2879s is with the output combiners. If you have ANY VSWR, you'll smoke them. I have a 4V that literally caught on fire after being converted. I've spoken with Sam about it indirectly (CB Doctor BDW argued with me on CB Tricks about this NOT being the case.... about 4 days later he confirmed that Sam concurred with my statements.... Stand up individual for admitting he was wrong like that, all other personal bullshit aside). The 2290 and 2879 boards differ only in the input and output xformer capacitors I think..... Anyway, for 2879s, 5 turns on the output with 1200 pf across it will get you 1200 watts or better
The resistors in the hi / mid / low probably need to be changed to corrolate to the slightly different input impedance (if you want the ratios to remain the same.... I use high power, anything else is nothing but an SWR issue)Lemme know how it goes.... Sounds like a good project, and sounds like bad xister in the drive section, or maybe a bad cap....
--Toll_Free
M800
I have the same amp, e-mail me for pictures, or anything I can do to help.
jharding437@hotmail.com
John
I have the same amp, e-mail me for pictures, or anything I can do to help.
jharding437@hotmail.com
John
Upgrade an M4V
I <<BELIEVE>> you're OK with the 2879 conversion. The problem with the M4V being converted to 2879s is with the output combiners. If you have ANY VSWR, you'll smoke them.
I have an M4V with MRF455 transistors that I would like to replace with a higher output device. Is this doable or should I look towards a newer amp?
I <<BELIEVE>> you're OK with the 2879 conversion. The problem with the M4V being converted to 2879s is with the output combiners. If you have ANY VSWR, you'll smoke them.
I have an M4V with MRF455 transistors that I would like to replace with a higher output device. Is this doable or should I look towards a newer amp?
You can..with some circuit changes depending on the device you want to use. Can you justdrop in different transistors...no. You need to match the input and output impedances of the circuit to match the devices and also make sure the idle current is correct. Also..while on subject...why? It is a lot of trouble for almost no noticable gain on the receiving end. Remember each time you multiply you output times 4 you only go up one S unit on the other end.
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