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Harmonic filtering on the input? Completely unnecessary since the radio driving has virtually no harmonic content.

Pi filter on output...

It's just an L-match... using #12 solid copper wire and a mica capacitor.

Magnet wire air coil & ceramic capacitor used for L-match...

I'm shipping the first proto unit today to a guy in PA... about 100 miles south of you. We'll see how he likes it.

Yes, this mic was designed primarily for the mobile environment... but certainly can be useful anywhere.

This works very good... one of my better ideas lately... LOL

It's a very unique experience. Power mic audio gain up close, with virtually no background noise coming through.

This is still a prototype... but the interest in this seems pretty high. Not sure how it will be offered yet.

heatsinkusa.com/

Absolutely correct... these are FETs characterized at 1MHz. They have virtually no gain at 27MHz.

@@TelstarElectronics Are these the same mosfets used in Rocket amps?

Yes...

@@TelstarElectronics Yes are they any good? for the device only costing 5$ they sure are expensive amps.

You get what you pay for. Good RF devices that work at 27MHz and run on 12V cost about $50 each... so you can figure how those 1MHz $5 devices work.

LOL... it's not quite that bad... but the gain at 27MHz is very low alright.

I don't sell much of anything anymore. People are not willing to pay for quality equipment. So, I only make good stuff for my own use.

@@TelstarElectronics I hear that.Thanks anyway professor.

www.telstar-electronics.com/SkyWave%20DX600T.htm

The 4 watt 29 was driving it good.Pegging that 500 in the corner.Pretty badass little amp!!The 29 might be doing 5 rms.

This is the best amp I've ever designed. I use one every day talking skip on channel-28. Everybody knows the ol' professor...

@@TelstarElectronics Good job!!!

48V

Compete? With those meatball designs out there made in a garage? Those are nothing but poorly built prototypes...

Since you're looking for a peak... actually, the whistle is likely better. It's a much purer frequency that doesn't vary in amplitude much.

Well, I don't have to deal with "shops" or "builders"... so I just tell the truth. Palomar sue me... LOL! For what?...telling the truth? Oh, and you're right... the MaxMod is also a scam.

@@TelstarElectronics I thought maxmod was the real thing until I saw a gentleman present and go over the math equations that disprove the maxmod. Then he tested it and the results matched the equations. I thought those videos got Palomar upset because he took down most of the videos without explanation. That's why there were rumors that this guy got threatened. If not by Palomar then it was trolls for CB shops like Mark Sherman. In fact, Mark Sherman still attacks these people relentlessly because they proved his beloved maxmod and ERF2030+ were BS and I am sure it threatened his scam CB shop business in the Winnebago. After all he gets around $400 to install the maxmod and the ERF2030+ into a stryker 955 because otherwise, according to Mark Sherman, the radios will "explode" or "catch fire" If you didn't get threats like they did then I bet Mark Sherman's losers and trolls are the reason.

Yes, radio related scams make the scammers a lot of money. They get very upset when you expose them. I don't have a thing to do with them, so I don't care if they like what I say or not...

The DX250 and DX300 will not work on those those bands because they have a tuned output.

Metal and plastic chassis are available from numerous places. I prefer the plastic... much easier to machine.

Yes, this home-made unit works great... makes no modifications to my house, and is very portable. The resonant match realized with the matching network inside the box gets this aerial to 1.1:1. It may not look like much, but the skip performance is awesome.

I sure like the MRF300... a great bang for the buck!

I use the antenna mostly for skip... so antenna height is not important. As for the matching network... a simple L-match.

@@TelstarElectronics what kind of impedance were you getting before the match, with the radials laid out flat like that? the 3'x3' aluminum bit- was that based on a calculation/some part of a wavelength? thanks- very interesting build

The impedance without the matching network was about 1.6:1. The 3'x3' aluminum plate was not based on any calculation... but more on mechanical and wind stability. I can tell you that it has survived a storm with 100mph gusts! Since it's only about 1/4" off the ground, the wind is not able to get under the aluminum plate enough to be an issue. I've been using this antenna for many months now... and it's surpassed my expectations for performance.

There's a matching network inside the box. The match is 1.1:1

Of course it still exists... this is a 1MHz transistor. Anyone who thinks it will work well above 5MHz, doesn't have a clue.

@@TelstarElectronics thx for Reply thx for the info 👍🏼

I can tell from your response that you're not part of "the CB crowd" I was referring to... :)

Yes, these are nothing more than general purpose 1MHz MOSFETs... that have like 3dB gain at 27MHZ. Rocket Box and Palomar amps use them. They work like crap.

Exactly right... I wanted a semi-portable antenna with some good gain... that I didn't have to mount on the house.

Nah... the Zepp is too big! I don't have anything to string up a 1/2 wavelength vertical. My 1/4 wave ground plane is all self-contained and needs only a surface to set it on.

There are some very clever "scammers" out there in the world...

My major focus is the low-voltage mobile environment... so I'm really not into FETs as a rule.

@@TelstarElectronics what would be a good drop in replacement for these? since they are probably a Chinese communist brand that costs maybe 20 cents each before rebranding. since you are an engineer and you have one in hand or you did a year ago. no doubt you could match it up on mouser.com prety easy. they are restricting the supply to drive the price even higher now. lits like 13 dollars a fet now. be nice if someone could bust that up a little.

There shouldn't be a drop-in replacement even considered... since these transistors are not meant to be used for 27MHz operation!

It's all good...