Just was wondering if anybody might know what class this small amplifier might be by looking at it and why ? I was wondering what all those little coils were in the upper right hand side of the amplifier as well ? Thanks for your time. SK
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WHAT CLASS MIGHT THIS BE ?
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Broken bead on the transformer neeeds replacement
The upper coil and C print looks like an low pass filter.
Look at the basis of the transistors, in SSB there should be 0.6 to 0.7 volt there for thrre bias putting it in class AB
left is input, right with damaged bead is output.
I see an bigger resistor from the + going to an switch, guessing that will be the switch for AM/SSB and provides an form of bias.
The upper coil and C print looks like an low pass filter.
Look at the basis of the transistors, in SSB there should be 0.6 to 0.7 volt there for thrre bias putting it in class AB
left is input, right with damaged bead is output.
I see an bigger resistor from the + going to an switch, guessing that will be the switch for AM/SSB and provides an form of bias.
thanks for your time Justme , so your saying it's class AB ? please forgive me , my knowledge of amps are slow to go, I just use them . 
Good eye concerning the bead (as you put it) What kind of damage might that cause ? (if any ?) thanks for the reply here. SK ...............
also on this amp is a switch the reads RMS and PEP , IM not used to seeing these kind of switches on amps ? Could this also me explained to me ? thanks .....I do have a few more pic's if that can help ? IM guessing this amp is pushing 30 years old ? It just says 100 BiLinear (black face) with on/off switch , SSB / am,fm,cw switch and the RMS/PEP switch.
Good eye concerning the bead (as you put it) What kind of damage might that cause ? (if any ?) thanks for the reply here. SK ...............also on this amp is a switch the reads RMS and PEP , IM not used to seeing these kind of switches on amps ? Could this also me explained to me ? thanks .....I do have a few more pic's if that can help ? IM guessing this amp is pushing 30 years old ? It just says 100 BiLinear (black face) with on/off switch , SSB / am,fm,cw switch and the RMS/PEP switch.
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MRF 455 x 2 will be about 150 watts pep, driven hard an bit more.
The design is Motorola, 1980 era, then with the MRF 454.
Put it on the PSU, set on SSB and use an simple multimeter to meeasure on thee base of the transistors in respect to ground, you should see 0.6 to 0.7 volt there if it is truly an lineair amp.
The bias circuitry in these amps was extremely simple, big resistor from +12 volt feeding an diode to - with resistor over it to limit the current through the diode. and an C to keep rf from that point.
Then an rf choke feeding the bias to the basis of the transistors.
Not the best design, but it worked.
Looking at the in/output transformers it was made for 10/11 meters.
The transistors in this amp were made in 1991, week 33.
Looking at the piccies moleculo might have an point that this is an class C amp, not fit to be used for lineair modes (ssb)
Though it would not be an big problem to add an decent bias and make it an lineair mode PA.
The broken bead will cause inbalance in the transformer, leading to different loading of the transistors and not matching the output of the transistors to an 50 Ohm load, but it is easily fixed, though some soldering has to be done, and an similar bead as the rest must be found.
If you know the brand and model, an search with Google will find an schematic diagram floating on the net, with the correct name of the beads, so you can order one.
RMS = Root Mean Square, or PEP = Peak Enveloped Power.
Average and Peak power mostly in these amps has not much of an meaning, just switching an capacitor over the measuring bridge, levelling the read out power as in cheap power SWR meters.
Good accurate reading out in PEP can only be done by an outside powered circuit that has been calibrated.
Most metering gives average power in SSB since the analog meter cannot follow the peaks of your power.
My Sb-1000 gives on such cheap meter 800 watts out, measured on an real PEP meter it is 1200 watts.
The amp was probably sold as an 100 to 150 watts amp in the AM (FM europe) era.
I saw then worse, without low pass filter, so it is an nicee little amp.
Getting it biassed for SSB might be an good option, done by an qualified man.
73,
Cor
The design is Motorola, 1980 era, then with the MRF 454.
Put it on the PSU, set on SSB and use an simple multimeter to meeasure on thee base of the transistors in respect to ground, you should see 0.6 to 0.7 volt there if it is truly an lineair amp.
The bias circuitry in these amps was extremely simple, big resistor from +12 volt feeding an diode to - with resistor over it to limit the current through the diode. and an C to keep rf from that point.
Then an rf choke feeding the bias to the basis of the transistors.
Not the best design, but it worked.
Looking at the in/output transformers it was made for 10/11 meters.
The transistors in this amp were made in 1991, week 33.
Looking at the piccies moleculo might have an point that this is an class C amp, not fit to be used for lineair modes (ssb)
Though it would not be an big problem to add an decent bias and make it an lineair mode PA.
The broken bead will cause inbalance in the transformer, leading to different loading of the transistors and not matching the output of the transistors to an 50 Ohm load, but it is easily fixed, though some soldering has to be done, and an similar bead as the rest must be found.
If you know the brand and model, an search with Google will find an schematic diagram floating on the net, with the correct name of the beads, so you can order one.
RMS = Root Mean Square, or PEP = Peak Enveloped Power.
Average and Peak power mostly in these amps has not much of an meaning, just switching an capacitor over the measuring bridge, levelling the read out power as in cheap power SWR meters.
Good accurate reading out in PEP can only be done by an outside powered circuit that has been calibrated.
Most metering gives average power in SSB since the analog meter cannot follow the peaks of your power.
My Sb-1000 gives on such cheap meter 800 watts out, measured on an real PEP meter it is 1200 watts.
The amp was probably sold as an 100 to 150 watts amp in the AM (FM europe) era.
I saw then worse, without low pass filter, so it is an nicee little amp.
Getting it biassed for SSB might be an good option, done by an qualified man.
73,
Cor
Sounds like some good info here guys. Transistors have date code , 91 hmmm ,might mean they were changed once if the amp is from the 80s ?
You right Bob , this little guy does have a blue lid on it.
So the RMS/PEP switch acts like a hi/lo switch , that's good to know.
Now this "low pass filter" this amp has would make the amp a cleaner class C ? Would this make SSB sound cleaner on transmit , or just a cleaner class C amp ? This is interesting ? Has nothing to do with biasing ?
I've personally been looking for a small amp in the 100 watt pep range to work SSB , This is where the learning lesson for me has come in. I kind of talked to you about that Bob in the past.
I got this amp very cheap , when I saw all those little coils I was thinking (or hoping) this would be the filtering I needed to sound good on SSB , from what Im reading it doesn't look like this will work for clean SSB operations ?
So this filtering in this amp only makes it a "cleaner" Class C amp ? I learned something new here ? I always just thought Class C was Class C no matter how I looked at it ? So some are surely better "made" then others.
The bead or change out the transformer should not be a problem for me , I have some spare parts from a old Boomer 250. I guess it's back to the drawing board in search of a small clean Class AB or AB1 type amp for good Clean SSB operations.
Maybe with only looking for less then 100 watts is asking to much for something like this ? I do realize the Texas Star or Blue Face Palomar's will work cleanly on SSB , (and I could just use the power level gears on those) If I had some good directions I could clean up the SSB with the parts needed , I just don't have the know how when it comes to amps as you talked about "Justme" (I appreciate the time it took you to explain as you did and to eveybody else.)
Transistors have date code , 91 hmmm ,might mean they were changed once if the amp is from the 80s ? You right Bob , this little guy does have a blue lid on it.
So the RMS/PEP switch acts like a hi/lo switch , that's good to know.
Now this "low pass filter" this amp has would make the amp a cleaner class C ? Would this make SSB sound cleaner on transmit , or just a cleaner class C amp ? This is interesting ? Has nothing to do with biasing ?
I've personally been looking for a small amp in the 100 watt pep range to work SSB , This is where the learning lesson for me has come in. I kind of talked to you about that Bob in the past.
I got this amp very cheap , when I saw all those little coils I was thinking (or hoping) this would be the filtering I needed to sound good on SSB , from what Im reading it doesn't look like this will work for clean SSB operations ?
So this filtering in this amp only makes it a "cleaner" Class C amp ? I learned something new here ? I always just thought Class C was Class C no matter how I looked at it ? So some are surely better "made" then others.
The bead or change out the transformer should not be a problem for me , I have some spare parts from a old Boomer 250. I guess it's back to the drawing board in search of a small clean Class AB or AB1 type amp for good Clean SSB operations.
Maybe with only looking for less then 100 watts is asking to much for something like this ? I do realize the Texas Star or Blue Face Palomar's will work cleanly on SSB , (and I could just use the power level gears on those) If I had some good directions I could clean up the SSB with the parts needed , I just don't have the know how when it comes to amps as you talked about "Justme" (I appreciate the time it took you to explain as you did and to eveybody else.)
Here's another one , Siltronics 100 , would this be class c as well ? or is it more suitable for SSB ? Thanks
Class C has the highest efficiency, but due to the waveform also the most "dirty" specs.
The low pass filter will attenuate the harmonics generated from the amp, hence less harmonic output wich can fall in bands you do not want to put an signal in, police ambulance etc.....
http://hem.passagen.se/communication/clc.html
Explanation for class c
The original basic concept of these broadbanded amps was made by Motorola in the 80's, the transistors were produced in week 33 of the year 1991, basically the PA can have been produced somewhere near the end of 1991 or early 1992.
The broadbanded amp design only took care of the input/output impedance of the transistors to be matched to the 50 ohm input
The full output after the broadbanded transformer includes all harmonics......
The low pass filter has to take care of those, leaving an clean signal to be fed to the antenna.
Cheapo PA's simply omitted these low pass filters, wich led to many problems transmitting harmonics in higher bands, where police, or other services were disrupted.
Class C amps have an merit in frequency multiplier stages (lowlevel) where you want to make an oscillator with an xtal multiply to much higher frequencies, like in an transverter from 2 to 23 cm.
Looking at the prices of the current CB radio's i rather see an ham radio with standard 100 watt beeing used, cleaner output, more bands and relatively much better recievers.
I got free an Lincoln, and an Superstar 3900 F the lincoln has been altered extensively with extra xtal filtering in the 10.695 MF and different first stage transistor etc.
MRF 455 in the PA, 65 watts output, nice for in the car on 10 meters.
Even when tuned to the max, it is no match for the FT100 from yaesu, now 8 years old.
That one does over 100 watts from the factory, clean signal, DSP, and small.
Hope you find an good PA, and maybe use this one to upgrade in time to class AB1
73,
Cor
knowledge is power
The above amp does have an bias, and is capable of doing SSB
See the large 75 Ohm resistor and 4.7 Ohm resistor devider, rf choke feeding the basis of the transistors, for tracking it needs an bias diode on the transistors/heat sink.
And and form of regulating the bias setting the optimum bias.
This is the el cheapo methode
The low pass filter will attenuate the harmonics generated from the amp, hence less harmonic output wich can fall in bands you do not want to put an signal in, police ambulance etc.....
http://hem.passagen.se/communication/clc.html
Explanation for class c
The original basic concept of these broadbanded amps was made by Motorola in the 80's, the transistors were produced in week 33 of the year 1991, basically the PA can have been produced somewhere near the end of 1991 or early 1992.
The broadbanded amp design only took care of the input/output impedance of the transistors to be matched to the 50 ohm input
The full output after the broadbanded transformer includes all harmonics......
The low pass filter has to take care of those, leaving an clean signal to be fed to the antenna.
Cheapo PA's simply omitted these low pass filters, wich led to many problems transmitting harmonics in higher bands, where police, or other services were disrupted.
Class C amps have an merit in frequency multiplier stages (lowlevel) where you want to make an oscillator with an xtal multiply to much higher frequencies, like in an transverter from 2 to 23 cm.
Looking at the prices of the current CB radio's i rather see an ham radio with standard 100 watt beeing used, cleaner output, more bands and relatively much better recievers.
I got free an Lincoln, and an Superstar 3900 F the lincoln has been altered extensively with extra xtal filtering in the 10.695 MF and different first stage transistor etc.
MRF 455 in the PA, 65 watts output, nice for in the car on 10 meters.
Even when tuned to the max, it is no match for the FT100 from yaesu, now 8 years old.
That one does over 100 watts from the factory, clean signal, DSP, and small.
Hope you find an good PA, and maybe use this one to upgrade in time to class AB1
73,
Cor
knowledge is power
The above amp does have an bias, and is capable of doing SSB
See the large 75 Ohm resistor and 4.7 Ohm resistor devider, rf choke feeding the basis of the transistors, for tracking it needs an bias diode on the transistors/heat sink.
And and form of regulating the bias setting the optimum bias.
This is the el cheapo methode
Thanks Justme , that clears me up on dirty and cleaner Class C amplifiers , thank you .
I figured that 75 ohm resistor had something to do with "cleaner" SSB operations , but as you said , El Chepo.
That was a very good post there Justme for anybody at least trying to get a better understanding of class C . It isn't always easy from the get go when somebody is trying to explain it.....for me anyway.
Once upon a time ago , I wouldn't even give it a second thought concerning class c weather it was dirty or not , didn't have much of a understanding to begin with anyway. Lord knows I've had some dirty ones in my time ! Hence people moaning and groaning about bleed over .
I've grown up over the years to appreciate a good clean amplifier , although being 90% AM'er only , class c's worked for me or I just used AB or AB1 type amps on AM only . (I just didn't know what I didn't , I just used them as I did) now SSB after all these years has interested me very much, and I've learned (for me) that I don't need a lot of watts to do my thing there. But I want as clean as possible wattage that I can get.
IM now learning the differents. Even after having many good AB type amps over the years when using AM only for the most part. I've gone through amps and radios like tissue papers over the years. I must admit , having the knowledge to look at a box and know what it is and have a better then most understanding of given box can surely be a plus.
I figured that 75 ohm resistor had something to do with "cleaner" SSB operations , but as you said , El Chepo.
That was a very good post there Justme for anybody at least trying to get a better understanding of class C . It isn't always easy from the get go when somebody is trying to explain it.....for me anyway.
Once upon a time ago , I wouldn't even give it a second thought concerning class c weather it was dirty or not , didn't have much of a understanding to begin with anyway. Lord knows I've had some dirty ones in my time ! Hence people moaning and groaning about bleed over .
I've grown up over the years to appreciate a good clean amplifier , although being 90% AM'er only , class c's worked for me or I just used AB or AB1 type amps on AM only . (I just didn't know what I didn't , I just used them as I did) now SSB after all these years has interested me very much, and I've learned (for me) that I don't need a lot of watts to do my thing there. But I want as clean as possible wattage that I can get.
IM now learning the differents. Even after having many good AB type amps over the years when using AM only for the most part. I've gone through amps and radios like tissue papers over the years. I must admit , having the knowledge to look at a box and know what it is and have a better then most understanding of given box can surely be a plus.
Beeing almost 56 now, looking back at when i started building my 1st FM transmitter at the ripe age of 12
Tubes were the way to go then.
Fast forward after building some AM transmitters, some CB for an short period in the early 70's
Learning all the way, reading up, asking other peeps, etc.
Then became licensed in 1977
The most important thing in your station is your antenna system, not the big ass amp, or fancy transciever.
After you perfected your antenna system you can go forward and improve the station.
Running kilowatts has no other use as to blast another station from the frequency or show off you have the power.
For communication you have enough power running 100 watts into an good antenna system.
Most my DX the last 31 years was done with 100 watts, the 1000+ watt amp seldom sees power applied, it was more an project to restore an beautifull heathkit SB-1000 to pristine condition.
Beeing proud of your station/signal comes not from running power, but putting out an clean signal, and good modulation.
One reason my FT 100 has the Am xtal filter buildt in, running 25 watts carrier and 100 watts modulated it sounds great.
I let the smoke out many parts experimenting, the only way to find the real limits of some projects, making mistakes along the way too.
You're on the right way looks like it from your remarks
I do train new hams, write on several fora, and explaining something isn't hard and if it helps someone, even better.
In the process you get an cleaner signal, run lots less risk and people around you will be happy seeing an clean signal.
Take care, have fun beeing on the air, and most important, it is an hobby, not an pissing contest, that is better left to kids showing off.
I'm past that stage, i know what i can do, and what i cannot do, still learning
One reason i choose the login name...
Cor
Tubes were the way to go then.
Fast forward after building some AM transmitters, some CB for an short period in the early 70's
Learning all the way, reading up, asking other peeps, etc.
Then became licensed in 1977
The most important thing in your station is your antenna system, not the big ass amp, or fancy transciever.
After you perfected your antenna system you can go forward and improve the station.
Running kilowatts has no other use as to blast another station from the frequency or show off you have the power.
For communication you have enough power running 100 watts into an good antenna system.
Most my DX the last 31 years was done with 100 watts, the 1000+ watt amp seldom sees power applied, it was more an project to restore an beautifull heathkit SB-1000 to pristine condition.
Beeing proud of your station/signal comes not from running power, but putting out an clean signal, and good modulation.
One reason my FT 100 has the Am xtal filter buildt in, running 25 watts carrier and 100 watts modulated it sounds great.
I let the smoke out many parts experimenting, the only way to find the real limits of some projects, making mistakes along the way too.
You're on the right way looks like it from your remarks
I do train new hams, write on several fora, and explaining something isn't hard and if it helps someone, even better.
In the process you get an cleaner signal, run lots less risk and people around you will be happy seeing an clean signal.
Take care, have fun beeing on the air, and most important, it is an hobby, not an pissing contest, that is better left to kids showing off.
I'm past that stage, i know what i can do, and what i cannot do, still learning
One reason i choose the login name...
Cor
Well said about the antenna and feedline Justme , case in point , it was 1985 when I started this cb radio hobby , my first few years I talked on a Cobra 85 Dynascan crystal controlled 23 channel AM only that did about 5 watt DK with about a 15 watt pep swing.
I used plug in crystals to talk on the lower frequancies , on 5 watts on a very old 5/8s wave super penetrator (IM fairly sure that's what it was) I talked all over the world on those 5 little watts on AM only. I tell people today and they just think IM full of shit. But I did.
I've known for years it had to do with that antenna and feedline back then that was really getting the job done for me as well as the DX being a plus for me.
I still see the same things nowadays with the ego radios and amps on AM , X-Force / Dave Made and all of the rest of those Class C monsters ! I don't think I ever ran more then 500 watts pep (dirty or not) over the years. I used to think as AM only and DX (or not) that I had to have more to be apart of all of "it" , to be able to say that I did and I made the trip , it was surely a good feeling (ego) on my part but AM only became a challenge so to speak.
I've been there and done that at my degree of AM only communications and I don't personally knock these people for the simple fact I've been there to some degree. Now I just want to do the best I can with what I can afford up to this point .
Antenna and feedline being numeral uno again , we do the best we can with what we have to work with , the rest is up to me and being as clean as I possible can be , is very importent to me , especially where SSB is concerned . I pretty much new how to get the job done on AM (dirty or clean) now after all these years IM going to talk SSB and IM going to do whatever takes to sound the best and cleanest that I can. And I won't settle for less.
I used plug in crystals to talk on the lower frequancies , on 5 watts on a very old 5/8s wave super penetrator (IM fairly sure that's what it was) I talked all over the world on those 5 little watts on AM only. I tell people today and they just think IM full of shit. But I did.
I've known for years it had to do with that antenna and feedline back then that was really getting the job done for me as well as the DX being a plus for me.
I still see the same things nowadays with the ego radios and amps on AM , X-Force / Dave Made and all of the rest of those Class C monsters ! I don't think I ever ran more then 500 watts pep (dirty or not) over the years. I used to think as AM only and DX (or not) that I had to have more to be apart of all of "it" , to be able to say that I did and I made the trip , it was surely a good feeling (ego) on my part but AM only became a challenge so to speak.
I've been there and done that at my degree of AM only communications and I don't personally knock these people for the simple fact I've been there to some degree. Now I just want to do the best I can with what I can afford up to this point .
Antenna and feedline being numeral uno again , we do the best we can with what we have to work with , the rest is up to me and being as clean as I possible can be , is very importent to me , especially where SSB is concerned . I pretty much new how to get the job done on AM (dirty or clean) now after all these years IM going to talk SSB and IM going to do whatever takes to sound the best and cleanest that I can. And I won't settle for less.
Had my share of 23 channels in that time, Pony, European produced Blaupunkt, 6 channel Pony handy, even old tube gear...
Used to talk all over europe when the conditions were good with the Pony handheld one, it's still in an junkbox somewhere.
On 11 meters. or the same on 10, you can get away with the groundwavee, after that you need skip or sporadic E
Even now when the sun is letting us down, i work on 10 meters all over europe with sporadic E with an simple Imax 2000, or the FD-4
For 6 meters i have an 5 element beam, heard the USA very faint today.
This is more rewarding as going to 20 meters, put on the SB-1000 and work the USA, wich i can do here every day if i choose to.
Wishing you all the best in your quest for quality
If you need something i can tell, just ask.
cheers,
Cor
Used to talk all over europe when the conditions were good with the Pony handheld one, it's still in an junkbox somewhere.
On 11 meters. or the same on 10, you can get away with the groundwavee, after that you need skip or sporadic E
Even now when the sun is letting us down, i work on 10 meters all over europe with sporadic E with an simple Imax 2000, or the FD-4
For 6 meters i have an 5 element beam, heard the USA very faint today.
This is more rewarding as going to 20 meters, put on the SB-1000 and work the USA, wich i can do here every day if i choose to.
Wishing you all the best in your quest for quality
If you need something i can tell, just ask.
cheers,
Cor
Thank you Justme for taking all your time on this one for me and adding good info on this forum , much appreciated and Cheers to you and your's from me and mines via So.Cal. Thanks
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