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Old 07-07-2009, 04:36 PM   #1
Andy N1ORK
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Default Motorola EB63 Power Amp

Any one ever build one of these? I got a kit of parts from an SK buddy of mine, but there were no instructions or parts layout diagrams. The EB63 is a 2-30mhz 100w power amp. It uses two MRF454 transistors and can put out 100w with 5w input. The barebones 'kit' is put out by Communication Concepts Inc. The problem I have, is, my circuit board is marked EB63a and the COR relay is encapsulated where the EB63 relay is open. So, the circuit board is a little different from the one at the CCI site. I have downloaded the Engineering Bulletin and schematic, but I need a parts layout diagram. I have also sent an email to CCI requesting assistance, but have not heard anything yet.
Here is a picture and schematic of it from the CCI site:



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Old 07-07-2009, 09:40 PM   #2
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Wish I could be of assistance Andrew, sorry. Just out of curiosity, what are you going to use it for and drive it with ?

Jim



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Old 07-08-2009, 03:44 AM   #3
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Don't know what I'll use it for yet Jim. I don't have a QRP rig. I got the kit, so I thought I would try and build it. Something to do in the w.....r I guess.



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Old 07-08-2009, 08:35 AM   #4
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Good reply Andy, the answer then would be "Practice"

My thought is that a 100 watt 2-30 meg amp would not be of much use with a Kenwood TS-2000... but it would still be fun to build
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Old 05-06-2012, 05:23 AM   #5
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Andy! I have a Amp that I retrived from a junk pile is a 10 amp in and 600 out is suposed to be 3 ot 30 mhz. Some one tried to put new transisters in . What a mess. just put on shelf for future use. might be for camper. but will have to install new finals. I think they are used by Chicken Band & might be dirty. Had a guy that lived a couple of houses from me that used to get me jumped on by other neighbors He was runing a 500 watt transister amp with a Starduster and splatering the whole neighborhood. I got my Ten Tec Omni-C back from Ten Tec friday. Was a gift from a friend. cost to repiar was $225.37 plus shipping. He bought in a yard sale for $10 . They didn't come with 12 & 17 but I had them added. One of these days I might get on HF. as I passed my General & Extra this year. Have a Inverted "V" up for 1.6 - 117' each side but need a tunner. Have been listning but have too much standing wave to talk.
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Old 05-06-2012, 05:43 AM   #6
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Dale,
Since I last posted on this thread, two things occurred. I sold the amp kit and I bought an Yaseu FT-817 QRP rig. At first I wanted to get a good SW receiver for the bedside, but a good one with SSB would cost at least $400. So I figured for $200 or so more I could have a good receiver that will also transmit and will cover 2m and 440 too. So now I can try QRP. Also, congrats on the Extra!



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Old 08-26-2014, 09:32 AM   #7
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Quote:
Originally Posted by Oldmax View Post
Andy! I have a Amp that I retrieved from a junk pile is a 10 amp in and 600 out is supposed to be 3 to 30 MHz. Some one tried to put new transistors in . What a mess. just put on shelf for future use. might be for camper. but will have to install new finals. I think they are used by Chicken Band & might be dirty. Had a guy that lived a couple of houses from me that used to get me jumped on by other neighbors He was running a 500 watt transistor amp with a Starduster and splattering the whole neighborhood. I got my Ten Tec Omni-C back from Ten Tec Friday. Was a gift from a friend. cost to repair was $225.37 plus shipping. He bought in a yard sale for $10 . They didn't come with 12 & 17 but I had them added. One of these days I might get on HF. as I passed my General & Extra this year. Have a Inverted "V" up for 1.6 - 117' each side but need a tuner. Have been listening but have too much standing wave to talk.
Back in the day, the State Police here had radios that would operate on 11 meters. It allowed them to talk to the truck drivers, listen to the truck drivers and allowed them to pull them over via radio when they wanted to do a mechanical inspection or look at their log books.

Maybe the radio in the car only had a couple of watts and they needed more power. I don't know, since it wouldn't be any more legal for them to operate 11 meters with more then 3 watts AM then it would be for you or me.

Some of the old low band fire and sheriffs radios were down in the 37 MHz range. Those radios worked great for talking over long distances without a repeater.

I was just talking to a guy yesterday that was telling me about how their group - Breezeshooters amateur radio club, used Starduster antenna's to talk ground wave on Monday nights for their club net. Since ground wave was only about 30 miles - I can't hear them from my location. I guess they were a good antenna for what they were, for talking ground wave...

Instead of using the antenna you presently have Max, why don't you buy a 160 meter off-center fed dipole antenna. That would get you everything from 440 mhz to 160 meters, with the exception of 12, 15, 17, 30 and 60 meters - without a antenna tuner!
Antenna tuners do not tune the antenna to resonance, they just trick the radio into thinking that the antenna they are feeding into is resonant. It keeps the radio from folding back its transmit power.
The transmit power is converted into heat, which is adsorbed by the tuner and the coax..
Not a real good way to transmit efficiently for any distance unless the band is wide open...
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Old 08-26-2014, 04:43 PM   #8
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Quote:
Originally Posted by Oldmax View Post
Andy! I have a Amp that I retrieved from a junk pile is a 10 amp in and 600 out
Did you mean 10 watts in and 600 out?

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Have a Inverted "V" up for 1.6 - 117' each side but need a tuner. Have been listening but have too much standing wave to talk.
I think you mean 160 meters, or 1.8 MHz. If you have room to do so, lengthening this to a little more than 130 feet per side would bring it nearer to 160 meters. If you don't quite have room for the added length, you could turn a right angle with each end and run the extra 14 feet parallel to the ground and high enough to walk under without getting strangled. To use it on different parts of the 160 meter band you'd likely have to adjust the lengths a bit (between about 137 feet for the lower end and, say, 125 feet for the upper end of the band). It ought to load up somewhere in or near the band, and then you adjust it again. Such antennas usually require some adjustment in length, but work well once adjusted.
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Old 08-26-2014, 05:19 PM   #9
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Antenna tuners do not tune the antenna to resonance, they just trick the radio into thinking that the antenna they are feeding into is resonant.
Almost true. They trick the radio into thinking the antenna isn't reflecting power back down the feedline to the radio. But even a perfectly resonant antenna can reflect power back down the feedline. For example, a two-conductor folded dipole, perfectly resonant, will have an impedance of about 300Ω and a true SWR of about 6:1 when fed by a 50Ω feedline.

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The transmit power is converted into heat, which is adsorbed by the tuner and the coax...
Almost perfect nonsense. That is not what a tuner does. Also I think you meant "absorbed" since "adsorbed" makes no sense here.

What a tuner does do is re-reflect that reflected power back up toward the antenna.

For example, suppose the antenna reflects 50% of the power back down the feedline, and also suppose for a moment that the feedline is lossless. Let's use a 100 watt transmitter and a perfectly adjusted (and lossless) tuner.

The transmitter sends 100 watts up the feedline, and the antenna radiates 50 watts and reflects the other 50 watts back down toward the tuner. The tuner re-reflects the whole 50 watts back to the antenna, which radiates 25 watts of it and sends the rest back down. The tuner reflects this 25 watts up again, and so forth. Eventually, the whole original 100 watts gets radiated. An RF wattmeter in the feedline would show 200 watts going up the feedline, and 100 coming back. This wattmeter would be telling the truth.

But if the feedline has any losses, the original 100 watts goes up once, with losses; half of what's left goes back down, gets reflected by the tuner, and goes back up -- three trips through the feedline, with losses each way -- and what's left after that goes up, down, up, down, up -- five trips -- and so on, with losses each time -- so the total loss can be a large fraction of the 50 watts that originally got reflected by the antenna. That's why a lossy feedline gets so much worse wth increasing SWR. Much of the original power makes multiple lossy trips up and down.

All of the losses occur in the feedline when the tuner does its job, and the transmitter sees no reflected power at all, and thinks the SWR is 1:1.

Clear as mud, right?
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