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What good 10 meter amps with SSB Biasing are ones to look for?

D

doffo

Well-Known Member
Oct 14, 2012
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Hello,

Lately been thinking about picking up a good 10 meter amp. Got an older Realistic HTX-100 id like to use with it. I am just not familiar with which amps that one could still buy good/used that have proper SSB biasing. Cobra XL 350 is one that comes to mind, but isn't that amp based off a Palomar? I would like to keep it a 2 transistor amp. Any brand recommendations appreciated. I also seen a Boomer Deluxe 250, but unsure if that has SSB Biasing.

Thanks for reading and hope everyone has a great day.
 

I recommend the TX 250 or Tx350. Built by Steve Canfield back in the 80s. Hard to find, and not cheap if you do find one. But great amps and bulletproof. First set of amps with the heat sink on top where it should have always been, they used 2879 and RF120 transistors (RF120s the best)

IMG_20200807_130409.jpg


250bias.png
 
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unit_399 said:
I recommend the TX 250 or Tx350. Built by Steve Canfield back in the 80s. Hard to find, and not cheap if you do find one. But great amps and bulletproof. First set of amps with the heat sink on top where it should have always been, they used 2879 and RF120 transistors (RF120s the best)

View attachment 74439

View attachment 74441
Click to expand...
Man... That looks great! One could only hope to get one for a good deal. :) Thanks for chiming in.
 
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The used amplifier market has gotten ridiculous as far as prices. A good class AB or even B amplifier for SSB use is getting hard to find for a fair price. I would watch the for sale section of this forum. Facebook market place in your local area or a local ham fest are also options. You might just consider having one built carlbuilt used to be X-Force amplifiers.

carlbuilt.net

Custom CB Amplifiers - Carl Built

Built delivers high-quality products with a 2-3 week shipping time. Get custom-built CB amplifiers today.
carlbuilt.net carlbuilt.net

donkeystomper.com

Donkey Stomper

Upgrade your CB radio experience with our top-of-the-line CW amplifiers. Our products are powered by the latest HG-2879 transistors for unmatched performance.
donkeystomper.com donkeystomper.com
 
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9C1Driver said:
The used amplifier market has gotten ridiculous as far as prices. A good class AB or even B amplifier for SSB use is getting hard to find for a fair price. I would watch the for sale section of this forum. Facebook market place in your local area or a local ham fest are also options. You might just consider having one built carlbuilt used to be X-Force amplifiers.

carlbuilt.net

Custom CB Amplifiers - Carl Built

Built delivers high-quality products with a 2-3 week shipping time. Get custom-built CB amplifiers today.
carlbuilt.net carlbuilt.net

donkeystomper.com

Donkey Stomper

Upgrade your CB radio experience with our top-of-the-line CW amplifiers. Our products are powered by the latest HG-2879 transistors for unmatched performance.
donkeystomper.com donkeystomper.com
Click to expand...
That what I was probably thinking what may happen if an amp doesn't turn up by the time im ready to put some money towards one. Appreciate the links.
 
Ranch55 said:
Or even a Texas Star......
I have been using a Texas Star DX500V in my mobile on 10 meters for years.....
Performs pretty well.....
Click to expand...
To be sure, wasn't there a difference in the Texas Star DX500v amps like the new vs old? I suppose the build quality or maybe the newer ones werent quite as good? Just making sure if that was ever a thing on the Texas Star amps.
 
Yes, the build quality did change.......
I have some DX350's and DX500's a little older that are in "like new condition" that I have upgraded and do have original Toshiba 2SC2879 transistors......
They perform quite well on 10 meters.....
 
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Ranch55 said:
Yes, the build quality did change.......
I have some DX350's and DX500's a little older that are in "like new condition" that I have upgraded and do have original Toshiba 2SC2879 transistors......
They perform quite well on 10 meters.....
Click to expand...
My 500 has been on 10/12 for almost a half a century, never had a issue with signal quality if you keep drive levels low.
I recommend the older TS's if you can get a unmolested one

73
Jeff
 
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unit_399 said:
I agree with Jeff. The early Texas Stars (unmolested) with 2879s are excellent. Also Boomer 250s (yellow face) also had 2879s and active biasing and were high quality amps. I still prefer the TX amps, but I haven't seen one for sale in like forever.

J.J. 399
Click to expand...
Crap....

I missed the Yellow Face detail about the Boomer Deluxe 250 amps.... I just bought
one, but it has a black face. :( Ugh... Should I return the amp before it gets shipped to me?

Looking through some pictures online, I do see some of the Yellow Face amps having 3749 transistors.

If the amp did have 3749 transistors, how hard are they to come by if the amp ever needed to be repaired later? Hoping it isnt difficult to source parts or to repair it.
 
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The majority of "cb" amplifiers are class C splatter boxes. There are a small number of nice AB amplifiers that were made. The Palomar tx amps from the 80's, The blue face Cobra xl and Magnum amps, a small number of blue face amps that say Palomar or Galaxy, The bulletproof line that are silver with wrap around heat sink. Messenger amplifiers were also very nice. Every black face amplifier that says Boomer, Gray, or Palomar that I have seen were all class C.
 
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9C1Driver said:
The majority of "cb" amplifiers are class C splatter boxes. There are a small number of nice AB amplifiers that were made. The Palomar tx amps from the 80's, The blue face Cobra xl and Magnum amps, a small number of blue face amps that say Palomar or Galaxy, The bulletproof line that are silver with wrap around heat sink. Messenger amplifiers were also very nice. Every black face amplifier that says Boomer, Gray, or Palomar that I have seen were all class C.
Click to expand...
Damn.. I mighta pulled the trigger too early. :( This isnt it, but the yellow colored one. No sign of it being a Class AB1?

boomer 250 yellow.webp
 
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I am just going to see if I can get a refund if it hasnt already been shipped out. Otherwise, ill just bite the bullet and keep it... Maybe ill try my luck next year... :)
------------
Update:

Order was cancelled in time. It wasnt shipped out yet. All is well.
 
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doffo said:
Damn.. I mighta pulled the trigger too early. :( This isnt it, but the yellow colored one. No sign of it being a Class AB1?

View attachment 74879
Click to expand...
This is one of many vertical transformer amps built that has a simple bias on the board that has been disabled.
If you look at the input you will see a choke from the top of the input transformer to ground, effectively killing the bias.
This was done because when building them they found that the amp was very unstable.
If they would have fixed the bias and added negative feedback to help lower the gain a little bit they would have been a decent amp.
They made a lot of 4 transistor amps like this as well....

73
Jeff
 
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