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RCI 2995dxfc amplifier

Pete Fender

Active Member
Nov 14, 2020
54
42
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I have an RCI 2995dxcf.
About a year old, voltage set at 13.8, peaked and tuned on a spectrum anylizer and oscilloscope.
The SWR is about 1.1:1.
I do not tweak my radio.
Since getting it brand new, it has blown three amp boards, the mosfet type.
I replaced them with boards from Barketts.
Is anyone having the same problem?
The radio just shuts down, lights out, but can be used as soon as the amp is disconnected from the power supply.
Disconnecting the amp from the power supply and the basic radio works.
It works without the amp.
I wish I could make one of these old two pill amps work, as I have two good ones from radios that were working.
Also everything is grounded at the chassis, has no effect.
I'm thinking of running a Texas Star amp, they last a long time if not over powered.
Thanks.
 

We call that four-MOSFET amplifier board the "Junior Firestarter".

The Galaxy DX98VHP with eight of them is the "Senior Firestarter".

One unadvertised result of putting many power devices in parallel is the max fault current that can flow through any one of them.

A single transistor can be fused for roughly the safe current of one transistor. Can protect if from overload at roughly the safe current that it's rated.

But put four of them in parallel, and you can't put a fuse or breaker in line smaller than the current draw of four devices.

But now any one of them can draw four times the safe current before the fuse/breaker trips. A four-to-one overload factor gets you smoke and collateral damage when one of them fails.

Eight-to-one gets you more smoke and collateral damage when one device fails.

No good way to put a fuse in line with each transistor.

Wouldn't matter, unless you installed an automatic transistor-replacement device in the thing. And a hopper full of fresh MOSFETs.

73
 
I've been trying to convince people not to buy any high power "10 meter" radios because, they literally have the worst transistor amplifiers EVER produced. The quality and reliability has never been so low. Even the very first transistor amps produced in the 1970's, were far better than what they sell for this band today. The more of these they can sell, the less the chances are that we will ever see them revert back to using real RF transistors. The market and demand for that has been removed by how easily these radios sell for a ridiculously high price.
 
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I called Barkett Electronics, who sell replacement parts for many brands.
I was told the RT1 mosfets currently used come from Malaysia, and have a high failure rate.
You can use the IRF 520 mosfets that are stronger, but do not amplify as much.
You will have less wattage.
My idea, so far, is to use an external amp, like a Texas Star.
I like the old two pill boards, but the wiring is different.
I'm not willing to attempt to rewire that part of the radio.
It was also mentioned to keep the bias under 3V, mine was measured 2.7v
If a mosfet shorts, the newer switching power supplies turn off everthing.
So, if your 2995 suddenly shuts off, disconnect the amp wires from the power supply.

http://stores.goldeneagleradios.com/
 
Well, I decided to get a separate amp.
These MOSFET amp boards are not as reliable as the older ones.
It's too much trouble for only 1-200 watts.
I still like the radio, all of the features I want.
I recommend the radio, but not the amp.
 
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Well, I decided to get a separate amp.
These MOSFET amp boards are not as reliable as the older ones.
It's too much trouble for only 1-200 watts.
I still like the radio, all of the features I want.
I recommend the radio, but not the amp.
Bingo! The manufacturers already have enough problems getting these junk transistors, to be somewhat OK as a radio final. Expecting to be able to string another 54,000 of them together and make a bigger amplifier stage from junk, is ridiculous. Write them and tell them we are sick and tired of the DX-2457 being the only base radio you can buy, that doesn't stick you with having to rip out a worthless $300 amplifier stage, just to get back to a decent barefoot radio. There is a very good reason they refuse to take the junk amp off the radio, prior to sale.

Some places charge $1,000 for this new RCI base. If it only made a reliable 25 watts of clean RF output, they would struggle to fetch $700 for the radio. They have figured out they can charge as much as an entry level HF rig, as long as they can make more watts and provide familiar features. To do that, all they needed was a glorified CB board, switching supply and the approximate $30 in parts, that they have used to create 200 watts or more, for 200 days or less.

They are getting more than a 10 to 1 return on the money they spend on the added PA board and you can be sure, the profit margin is far less on the rest of the components. If they drop the cheap PA board or used real RF MOSFET's, they would lose more of their profit margin, than they are willing to simply give up. You have to speak with your wallet and not just your mouth in this case.

STOP BUYING THEM. Force every high power export to sit on the stock shelf indefinitely. Until such time as they are willing to replace four junk output transistors (8 in other radios), with a matched pair of the current Mitsubishi 100 watt RF MOSFET's, that HF radio manufacturers knew enough to switch over to a decade ago! In bulk, those parts might cost them $40, for the pair needed in each radio. Rather than eat it, they'll charge you double. To be frank, I'd welcome that over what they are trying to get away with on unsuspecting customers today.

My first employer once told me, "We can legally charge the customer whatever we want! As long as we are honest about what we are selling them in advance." That led to having to identify the common fuse, as "the overload protection device". So keep in mind, there are literally hundreds of different 100 watt mobile radios being manufactured today, that use reliable RF output stages. The ONLY place that hasn't flat out rejected the use of inferior switch mode MOSFET's in linear amplifiers, is the illegal 11 meter market...

I've got to say, some of these radios are just filthy too. I don't know if something happens when one switch mode FET starts leaking, or if the bias is just set way off. In any event, the amount of spectrum they can take up, once you add another amplifier stage behind it, is amazing! They're barely down 10db, when you're 10 Khz. away. Every amplifier stage you add after the radio, typically adds at least another 10db to those problems. If we can't get people to be concerned about spectral purity, at least demand some reliability for your money.
 
I like the idea of those 1Kw LDMOS amps, but can only find the basic assembly, without the LDMOS it self, and the case, switches, etc.
But there are still 2290 "pill" types being made.
I'm used to a separate unit anyway.
I replaced the stock 25 amp power supply with a 45 amp switching power supply.
They have a self resetting protection circuit built in.
They are also used in servers like the one where I work, that backs up about 20 computers.
I could run an external amp off the same power supply.
 
Also Barkett told me you can add a second final to these radios, and get 35 watts without hurting anything. the same circuit board is used in this manner in many bases and even mobiles.
But that puts you back to the Excalibur and Galaxy DX days.
 
I like the idea of those 1Kw LDMOS amps, but can only find the basic assembly, without the LDMOS it self, and the case, switches, etc.
But there are still 2290 "pill" types being made.
I'm used to a separate unit anyway.
I replaced the stock 25 amp power supply with a 45 amp switching power supply.
They have a self resetting protection circuit built in.
They are also used in servers like the one where I work, that backs up about 20 computers.
I could run an external amp off the same power supply.
If you are looking for an external amp, I have a Texas Star DX350 sitting here that might be looking for a new home if the price is right. It has Toshiba transistors and is in cosmetically good shape except for the holes that were previously drilled in the lid. I covered them with electrical tape, so at least they blend in a bit.
I have also upgraded the power wire to 8ga with a fuse holder.
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Well, there is a guy in Tampa that is running one of these, pictured.
He gets them from a guy in Oklahoma.
It's a custom unit that is a 1 x 4, puts out about 1Kw which is about average for the big bases here in the South Florida area.
I'm thinking $600 for 1 Kw, new, is a good idea.
I have a RF power control that can dead key from 1 Watt to 35 Watts, this unit can handle a 200 Watt dead key.
The more you feed it, the more it roars.
I would not be looking for it to put out as much as it is capable of, but about 600-700 would let it last a while.
It's a 1 x 454 driving 4 x 2879's.
 

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Well, there is a guy in Tampa that is running one of these, pictured.
He gets them from a guy in Oklahoma.
It's a custom unit that is a 1 x 4, puts out about 1Kw which is about average for the big bases here in the South Florida area.
I'm thinking $600 for 1 Kw, new, is a good idea.
I have a RF power control that can dead key from 1 Watt to 35 Watts, this unit can handle a 200 Watt dead key.
The more you feed it, the more it roars.
I would not be looking for it to put out as much as it is capable of, but about 600-700 would let it last a while.
It's a 1 x 454 driving 4 x 2879's.
Doesn't look like too bad of work, but I would still want it to be biased.
 
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