Communications Concepts

They are an odd outfit. Reportedly they are legal to sell ham linears that don't strictly meet the rules for a ham linear.

Might just Google them for a better picture. Never really looked into it.

They have been around a long time, so it should be safe enough to do business with them.

When they quote you a drive-power limit, it usually means peak drive power, like for SSB or CW. That 5-Watt number probably does not mean AM-carrier power.

Only hams have radios with only 5 Watts PEP.

Your stock out-of-the-box Cobra 19 should deliver around 16 Watts PEP.

73

Here is a link to the thing.

http://www.communication-concepts.com/eb63a-140w-hf-amplifier/


Pretty sure I'm right about a bone-stock CB overdriving it by a margin of three-to-one or more.

It's a kit to build the circuit board alone.

No heat sink.

No enclosure.

No connectors, power switch, pilot LEDs, etc.

Does have a nice, big relay on the board.

73

Designed to be clean, not cheap.

To be a legal ham linear, it would still need a low-pass filter behind it for the band you're using.

The low-pass filtering and the band-switching that select the correct filter cost money. This is a lot of the higher cost-per-Watt you pay for a legal ham linear.

The illicit 11-meter boxes leaves all that stuff out. Does cut the cost of production in a big way.

73

Odd how these subjects come up. I was just discussing this with someone earlier today that should know better than to answer the phone when I call . Refer to AN762.pdf for all but the MRF454. The mathematics are clearly discussed in AN779.pdf for plastic TO220 transistors but the principals still hold for anything from a 2SC2166 to a 2SC2879. I've supped 2SC2166/2SC1969 into the AN779 design with little effort.
I don't have the details for the MRF454 anymore but I did the math and applied it to a bare bones 2 transistor amp with predictable results.

Bias adjustment is critical to linearity and the lifespan of the transistor. Deviate from the spec at your own risk or a quality test fixture.

Nomad is correct, no matter what the white paper seems to say. Biased "on" to AB the MRF454 IS VERY SENSITIVE TO DRIVE. It's something to be whispered at , not hit with a hammer. I learned the hard way and ended up using a 5db input pad as well as making sure AMC and ALC were in place and verified to be working. ALC overshoot and undershoot is a topic for a very long discussion .

I just posted this elsewhere today so ...

It just "might make it at 3-4 AM and 10w SSB


This absolutely will. That takes care of the input .



That takes care of the output.

The rest of the porn, I mean parts can control boards can be found here .

https://www.w6pql.com/parts_i_can_provide.htm#23cm

So where does it stop? Well it starts with a $120 two transistor box and ends up being a 1.8 to 6m piece of technological coin. Getting close to $600...

or



Ask me about it sometime...