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Pride KW-one
- Thread starter TIN_CAN
- Start date
The price is good if it works but, keep in mind Pride was really a CB amp company. This "KW One", uses a single 4CX250B tube that has a plate dissipation of 250 watts. That tube runs comfortably around 500 watts PEP. With enough cooling and power supply, they can do about 1KW PEP, but it will cut tube life way down and runs the risk of internal tube arcs. This unit also has the input set up to take a high drive level from a 100 watt PEP radio to make it more "hammy".
Thanks for the info Shockwave, Like i said I have no experience with tube amps but this came up on local classifieds and seems like a decent price, exterior looks clean but no pics of inside Waiting to hear back from the guy with more info on the amp. Chances are it needs works for the price.
You're welcome. If it needs work, it will likely take someone with decent skills. This amplifier was a bit more complicated than most triode tube amplifiers. The 4CX tetrode tube needs additional screen and bias power supplies and this one has some electronic protection too. Some people that can fix a triode tube amp, may not understand a problem in the control / protection, or bias circuits used here.
You don't need to be a rocket scientist to service this amplifier, just don't expect it to be as simple or straight forward as a Heathkit SB-220 inside.
I should also add that if you buy it and it needs work, if you can safely work on tube equipment with lethal voltages inside, there are many members on this forum that can walk you through a repair. The test meter, a few pictures and soldering skills, have fixed many broken pieces of equipment through this forum. You don't need to know how to fix it yet, you can learn that as you go here.
Just know it can kill you if you don't know how to insure the filter caps are discharged or you work on it while powered up. The electric chair uses 2,000 volts and so does this! It's nothing to be afraid of, but it does require learning a few basic rules that must always be respected with HV equipment.
Just know it can kill you if you don't know how to insure the filter caps are discharged or you work on it while powered up. The electric chair uses 2,000 volts and so does this! It's nothing to be afraid of, but it does require learning a few basic rules that must always be respected with HV equipment.
Every KW-one I have ever seen was beaten to death. Literally.
The tube it uses requires less than 2 Watts to drive it to full bore. The DX300 model is a version of the same amplifier meant to use with a barefoot CB. It uses resistors in the input circuit to lose about 9/10 of the radio's drive power and feed the remaining 10 percent of that power to the tube.
The KW-one uses a 100-Watt dummy load made from 2-Watt resistors to make it a "high drive" amplifier. Ideally those resistors will now take 98 percent of the drive power, feeding only 2% of it to the tube. The tap-off point from these resistors can be changed. This will configure it for more or less max drive power. Seems inevitable that someone moves this tap point higher and higher until the tube gets a fatal overdrive level, trying to get "just a little more" from the wattmeter. What comes next is an even bigger driver until the resistor string gets burned from the excess heat.
By the time I see one of these several unsuccessful repair attempts have already been made.
If you can see it demonstrated and it works, it should be worth $400.
But sight unseen, make sure the seller is trustworthy if he says it's in good working condition. It's been about 44 years since that model hit the market. Consider that even if it's "all original" that means it is years overdue for new electrolytic caps.
The high voltage power supply is famous for self-immolation.
Color me skeptical.
Full disclosure: My company sells upgraded replacements for the exploding power supply circuit boards. They're on Ebay.
One last thought. If you're planning to have this thing shipped, the plastic blower should be unhooked from its metal mount flange and laid intake-down against the chassis deck. A layer of bubble wrap will cushion the plastic against the metal. A length of 2-inch wide fiberglass-filament strapping tape should get stuck to the front face of the lower chassis, and stretched diagonally across the blower motor, and lapped to the rear panel at the opposite corner. Another piece of strapping tape goes diagonally across the blower to the other two corners. Leaving the blower mounted to its flange will probably destroy it in transit.
73
The tube it uses requires less than 2 Watts to drive it to full bore. The DX300 model is a version of the same amplifier meant to use with a barefoot CB. It uses resistors in the input circuit to lose about 9/10 of the radio's drive power and feed the remaining 10 percent of that power to the tube.
The KW-one uses a 100-Watt dummy load made from 2-Watt resistors to make it a "high drive" amplifier. Ideally those resistors will now take 98 percent of the drive power, feeding only 2% of it to the tube. The tap-off point from these resistors can be changed. This will configure it for more or less max drive power. Seems inevitable that someone moves this tap point higher and higher until the tube gets a fatal overdrive level, trying to get "just a little more" from the wattmeter. What comes next is an even bigger driver until the resistor string gets burned from the excess heat.
By the time I see one of these several unsuccessful repair attempts have already been made.
If you can see it demonstrated and it works, it should be worth $400.
But sight unseen, make sure the seller is trustworthy if he says it's in good working condition. It's been about 44 years since that model hit the market. Consider that even if it's "all original" that means it is years overdue for new electrolytic caps.
The high voltage power supply is famous for self-immolation.
Color me skeptical.
Full disclosure: My company sells upgraded replacements for the exploding power supply circuit boards. They're on Ebay.
One last thought. If you're planning to have this thing shipped, the plastic blower should be unhooked from its metal mount flange and laid intake-down against the chassis deck. A layer of bubble wrap will cushion the plastic against the metal. A length of 2-inch wide fiberglass-filament strapping tape should get stuck to the front face of the lower chassis, and stretched diagonally across the blower motor, and lapped to the rear panel at the opposite corner. Another piece of strapping tape goes diagonally across the blower to the other two corners. Leaving the blower mounted to its flange will probably destroy it in transit.
73
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The DX-300 and KW-one are also notorious for having the negative bias for the control grid dropping out from the calibration potentiometer failing due to oxidization.(scratchy)
When this happens the tube is full on even with no drive and won't last long.
The negative bias is the FIRST thing that should be checked before operating one of these amps.
When this happens the tube is full on even with no drive and won't last long.
The negative bias is the FIRST thing that should be checked before operating one of these amps.
Nomadradio you really know your stuff with these old tube amp, with all this
I think I will stay away from this one, as it about 3hrs away from me, and not looking for something that will need work, best to stick with something solid state. Neat looking amp though. Thanks all for your input.
Roger that. The upgraded low-voltage board we sell for those amplifiers has a handful of parts that serve to protect that control from surges. The first time a tube gets overheated and goes "SNAP!" the factory bias control is at risk of damage. And so is the next tube that gets installed if that check is not performed first. A damaged control might hammer your next new tube. Got tired of replacing those controls and redesigned the bias circuit to make the control more robust.
Considering that it's over 40 years old, odds are that some part of upkeep or another has been neglected over the decades. If so, it will need work.
And if someone has spent the money to catch up the last four decades of maintenance, the price will NOT be that low. Anyone who spends that money will want to get it back from the sale price.
I always do.
73
Hello. I am brand new here just looking very hard where I might find, buy, steal, copy, barder LOL....User Manual for an old Pride 100 Amateur Radio Bi Linear 12v Amplifier.
@PlanBnetwork - You have cross posted the same request on several postings.
https://web.archive.org/web/20191210154505/http://www.cbtricks.com/Amp/pride/index.htm
Might be similar to the P150 with MRF455A stud mount transistors.
https://web.archive.org/web/20191210154505/http://www.cbtricks.com/Amp/pride/index.htm
Might be similar to the P150 with MRF455A stud mount transistors.
BJ radionut
Supporting Member and 6m addict
Yes, he did. Like 6-8 different threads. I deleted all but this one, as he even posted in the eBay locations. He posted in every thread he opened.
He will likely get an answer here but will never see it.
He got PO and left, once I informed him to cease the multiple location posting.
He will most likely go to another forum and B***H we are jerks here!
I am guessing he required an answer 30 seconds after he made post.
Sorry
All the Best
Gary
