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Reviews Categories | Amplifiers: RF Power - HF & HF+6M | Communications Concepts Help

Reviews Summary for Communications Concepts
Communications Concepts Reviews: 13 Average rating: 4.3/5 MSRP: $(missing—add MSRP)
Description: These guys supply all of the design and parts to build any kind of solid state amp. From 12volt versions running from 140 watts to 1kw, 50 volt versions runing the same power to VHF and UHF amps. All of the designs are from Motorola. For example I priced the parts to build a 1KW 12volt amp using there design and parts but replacing the MRF421 they use with the 2CS2879 and found it to be just under $500. You SAVE A LOT OF MONEY by doing the assembly work yourself. Check out the site and see for yourself.
Product is in production.
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KD0NFF Rating: 5/5 Aug 19, 2011 12:33 Send this review to a friend
EB63a is awesome as are low-pass filters  Time owned: 6 to 12 months
EB63a is a simple build, but as was mentioned the EB63a IS different than the EB63.. not by much, but there are some differences, namely the bias resistor has been increased in value to 82Ohms, and the bias diode is of a different type resulting in minor board changes. Also the original EB63 relay is hard to find and expensive, so it has been swapped with a newer type which also resulted in a minor PCB layout change. The updated assembly instructions for the EB63a are not hard to find. Google is your friend.

I added negative feedback to my EB63a, consisting of a 47Ohm 5W resistor, .01uF ceramic cap and 15uH VK200 choke in series between the collector and base of each transistor. This flattened the gain curve of the amp so that it produces a pretty even level of power output across it's bandwidth.

The low-pass filters work fine, providing 45+dB of attenuation in the stop band but due to their nature require patience in constructing them. As long as the instructions are followed they seem to work great so far.. the 300W PEP rating is conservative, the toroid size allows for up to 500W PEP.. it's important to recognize the limitation that the filters are not usable for more than 75-100W continuous (100% duty cycle 24/7) as the capacitors can overheat during continuous duty above 100W.

AD6KA Rating: 0/5 Jun 26, 2011 22:51 Send this review to a friend
Prototype, Not Production Product  Time owned: more than 12 months

Lets face it, they just have a clamping diode to
control the bias to both PA's, and NO WAY AT ALL
to adjust either Bias Voltage or Bias Current,
much less adjust it for each device, the proper way!


Without a proper Bias Control Circuit, they are SPLATTER BOXES, unless run at 60 watts or so.

Better off to buy an AN-762 or OTher design that allows you SOME conreol of Bias Curent!

They have WAY too much gain, and despite Old
Wives Tales about "cleaning up amp", putting Low
Pass Filters on them will ONLY REMOVE HARMONIC,
NOT IMD Distortion, the real problem.


I know a ham who built the CCI LPF filters. You
know what the harmonic suppression was? 1-2 dB!
Put one on a spectrum analyzer and check yourself.

The PC Board, T/R Relay and parts shown on the
CCI web site for the EB63 are no longer being
shipped.!! You DO NOT GET WHAT YOU SEE!

THAT model has been replaced with the "EB63a".
This is a much cheaper, poorly made (thin
traces, thinner pc board copper) PC board which
uses a $3 PLASTIC Omron PC mount relay.....
BUT CHARGING YOU $13 BUCKS for a nice looking
sturdy Open Frame T/R real. They're CROOKS!!

Write me at QRZ nd I will send you photos &
Scematics of BOTH the "EB63" shown on the CCI
website and the "EB63a" now shipping.

CCI are liars. Believe it!

The "Motorola Application Notes" from which
these schematics were taken were ONLY MEANT FOR
design an amplifier with MRF BiPolar PA Devices.

W1RKW Rating: 4/5 Jul 25, 2010 10:04 Send this review to a friend
EB63 - Needed Work but Works Good  Time owned: 0 to 3 months
I bought one with the intention of operating it with the Small Wonder Labs Retro 75. This is a 2 watt AM transciever.

The amp as is, is a CW and single sideband linear amplifier. I knew this going in and knew the input power would need to be attenuated somewhat.

Tapping holes into metal was something I never did before but it went flawlessly after reading about tapping metal. Other than that assembly was straight forward.

Amp operation I was not happy with once assembled and powered. The carrier waveform was distorted from 10watts out to 150watts out. The amplifier also oscillated while in stand by. True sign of a high gain amp. The Retro 75 didn't like the input impedance presented by the EB63. So an attenuator was a must. I wonder how many observed the output of their amplifiers on an oscilloscope? Just curious.

Anyway, after a few modifications like increased bypassing, increased bias and negative feedback the amp was now tame. It now works with the SWL AM Retro 75 with a carrier level of 45watts out.

If anyone uses this amp, I highly suggest you check its output at the frequency of operation with an oscilloscope before putting it on the air. Also suggest the use an LPF.

Despite some modification I am pleased with the end result.
5R8GQ Rating: 5/5 Jan 8, 2009 22:37 Send this review to a friend
EB63 Works Great!  Time owned: months
I have built two EB-63's and both work great. They state 140 watts output, but I get close to 200 watts on 40m and 80m. Very simple to put together, though you will have to drill and tap holes in the supplied heat sink.
I was reticent at first about getting this amp because the bias for both PA transistos is controlled just by a clamping diode. But with careful setup they work fine for me. One was used with my Elecraft K2 until they came out with the 100 watt mod, the other one I built and put on the shelf, and plan to use it as the PA for 20m QRP SSB rig I have built (WM-20) from Small Wonder Labs. CCU also sells low pass filter kits and all kinds of solid state amp components.
W4RCY Rating: 5/5 Feb 10, 2008 18:31 Send this review to a friend
eb-63  Time owned: 0 to 3 months
a circuit board, all parts, and basic printed instructions. A great amp that requires very little input. The people at communications concepts are extremely friendly and knowledgeable. A great experience which produces a super amp. Thanks,
NH7O Rating: 4/5 Aug 21, 2007 19:15 Send this review to a friend
Very Satisfying  Time owned: 6 to 12 months
I built the EB-104 kit using the venerable but hard to fault MRF150s. This is a lot of power in a small package, and the copper heat spreader they recommend is probably a good idea. But in normal use my amp runs at a surprisingly cool temp, and so given the cost and extra trouble to drill this massive piece of copper, it may not be such a strong requirement. The kit is simple enough, as others have said, but does require some skill in drilling the heatsink.

I was able to find 4 used MRF150s on eBay for $25 each. They don't really need to be a fully matched set, as mentioned in the kit data. The spread on these parts is not so great that the seperate biasing circuits can't compensate sufficiently. Think about it: you may only have to buy one set in your lifetime. The tube is dead.

But with your finished circuit board in hand, you have only just started. The main work in building these amps is in the six harmonic filter circuits. The parts count is high and one should think things out better than I did when starting. The website of K0GKD is a good place to start. Also the website of K6IF, and the links he posts there. I would recommend that the extra effort in building a diplexer type of filter is worthwhile, as described in the ARRL handbook and elsewhere on the net. It may be one factor why my amp is surprisingly cool running, as all the third harmonic power is dissapated outside the amp and not in the transistors. Less IMD as well, which is always a good thing.

I didn't include any fancy control circuitry, just some relays on a foot switch. Although I have managed to inflict some high SWR conditions on the amp due to arcs in my tuner, the transistors are unfazed. I tend to keep my eye on the watt meter.

The HF amplifier is of the last area in which homebrew is possible. And it's very satisfying when you see the unit work with no fuss, as all the hard engineering work has been done by the folks at Motorola >25 years ago.

Anonymous Rating: 5/5 May 29, 2003 20:07 Send this review to a friend
Buy and try it  Time owned: more than 12 months
I built 2 1200 watt amplifiers using the EB27 kits and built a 28 volt 160 amp power supply. They work great. The output filters used the values supplied by CC in their docs and I used vacuum relays to switch them. These parts are first rate. A potential buyer and builder should understand that this company does not supply what I would call a kit. You can buy most of the parts from them but there is alot of accurate drilling needed to properly mount the boards and suitable heatsinks with the correct thermal resistance are needed. If you have built a tube amp from scratch you should have no problem.
CT1FKC Rating: 4/5 May 29, 2003 17:47 Send this review to a friend
nice kit  Time owned: 0 to 3 months
I didn't try it yet. but it seems to be well designed and rugged. it arrived with lots of information.
I have ordered a set of low-pass filters that have a great look. lots of parts, including wire and parts to fix toroids to each pcb.
I'll try to test it with my homebrew transceiver, wich is the only reason to give only a 4 right now.
I also have to say that were very patient, because they solved a mistake that happened at the customs service with my address. they were not responsable for that, but they solved it.
nice people, I can say.
only hope to build it and avoid to blow transistors.
KA7QOR Rating: 5/5 May 14, 2003 10:40 Send this review to a friend
simple kit, good quality  Time owned: 0 to 3 months
I just finished building a EB27, using a pair of MRF422s. I bought the PCB, transformers, chokes and instructions from Communications concepts. I found all the other parts myself. Instructions are easy, if you have some technical skills. I dont recommend this kit for someone with no electronic skill, but minimal skill is enough. They were very polite and helpful answering all my questions by email. My reports all say that my audio is clean. Seems like a good solid amp. Im satisfied!
KG4OVB Rating: 5/5 Dec 11, 2001 01:13 Send this review to a friend
Fantastic Project  Time owned: 0 to 3 months
I bought this "kit" to put on my FT 817 when it is in my truck. I have the EB-63.

First of all, a MONKEY could put this thing together. It's great! 5 watts in gives me almost 200 watts out.

Here are the PITFALLS that I fell into, and hope that someone else who builds this will see this and not fall into the same ones.

I had alot of probs with RF feed back. The thing would not work with a tuner. It would just go nuts and the SWR was all over the place.

1. Use really good coax for the internal runs from the SO 239's.
2. Run them as far apart as possible.
3. Build a little box out of foil or metal around the INPUT SO239 and the input portion of the board.Sheild it from everything else. (I used aluminum foil folded up about 4 layers thick. I made a complete box to fit over the intire input portion.)


It works great now.

The heatsink that CCI sells for it is more than enough to keep those transisters COOL AS A CUCUMBER!

GREAT AMP! I would recommend it to anyone.
$86.00, you just can't beat the price!

(my call changed and I cant change it here yet)
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