10 - Building & Testing an RF Amplifier

Nick M0NTV documents the building and testing of a Wes Hayward Termination Insensitive Amplifier.

The article 'A Termination Insensitive Amplifier for Bidirectional Transceivers' by Wes Hayward W7ZOI & Bob Kopski K3NHI can be downloaded from Wes' website:

No transistors were harmed in the making of this video!

[franklewon]

In the old days your right would keep you warm! Have you seen any of the 1960's QST magazines? Quality home brew rigs.

[jackhaefner]

Hi Nick. I'm working on Pete Juliano's DCR; learning from Tony Fishpool and others about how to test the stages. Your video is very helpful to that end.

[InteraliaTony]

Hi Nick. Great example of how useful relatively "budget" test equipment can be. Your 'scope has far better FFT than my Siglent bought in 2016 - and of course the TinySA is dead brilliant - also along with great value signal generators from the far east.
For cleaning PCB can I recommend a Garryson "gentle abrasive block" (mine is fine - 240 grit). It won't leave nasty bits of wire wool around and it will last so long that you will be passing it down to your grandchildren. Mine was seven quid when I bought it around seven years ago and it has cleaned a lot of boards since then. Thanks for the video. - de G4WIF

[williamglew]

Hi Nick i found a laundry marker pen was a good choice when it came to marking the boards as it as a fine tip

[martsmiscmix]

Nice video, once again Nick, and I too am a fan of the "Julian Ilett Blu-Tack Third Hand"technique!

[Paul_VKHN]

A classic! Only one problem, it is fixed gain, not ideal as an IF amp which you really want to be AGC aware. The Bitx es omit AGC and the after market AGC options all use audio gain control, a compromise. Thanks for sharing!

[TheArtofEngineering]

Thank you 🙏 for sharing …. Just started home brewing again! This is most helpful.

[skydm]

Fantastic build! Just got my ham license and am digging into some first projects. Thanks for sharing! Can you point me in a direction to a book you recommend to build amplifiers of different frequencies? (HF, VHF, UHF)

[germanjohn]

Use a paper cutter to cut boards it is working great and square I found an old one for a couple of bucks at a yard sale. It works like a charm

[josedasilva]

Excellent project!. Thanks for sharing. Is it capable to handle 900Mhz ?

[UKSimon]

W2AEW has just put up a video on making measurements on this amplifier using a VNA.

[MXYM]

Really appreciated. It would be nice to see a whole project - with each module built and tested separately and showing now they are connected warts and all. I seem to trip up at stage-to-stage impedance matching and I would like to see how others attempt the stage connections. Thanks and keep 'em coming. Kevin M0XYM

[phitrow]

have you linier parameter this amplifier? Very interesting..
How many gain* on 100 mhz?

[Mofachannel]

Hello and thanks for good videos
I have a question iwant to buy lna module there is some types like 20db gain I know If I put 50mv pp in input I will have a 500mv output but ididnt tested it for 400mv input will I have 4v pp at output on 50 ohm load If not why???

[eugenepohjola]

Howdy. Nice.
I would suggest etching the board. Use ferrochloride (iron chloride) availe from any drug store. Solve it water and neutralize with chalk after use. Cover the copper with adhesive film and cut out the borders with a hobby knife or scalpel. Then drop the board into the solution.
Another popular way is to cut a piece of board into 7 x 7 mm or 10 x 10 mm tabs. Then just glue the tabs on the board.
Regards.

[danielraducu]

can i use this schematic for a 27mhz transmitter ? i need a range of 2km for a aeromodel...?

[Greg_Chase]

I offer you a design we built relying on tunable RF. Several of our group have radio, antenna education and work history, both military and in industry.

1) 10 layers of store-bought aluminum foil, each layer separated by a thin insulation layer
2) RF applied via eddy current coils placed radially, and adjacent to (but not touching) the 10 layer lamination
3) the aluminum/insulator 10-layer lamination is positioned horizontally on the workbench
4) the initial RF frequency was 16.28Mhz, due to the skin depth of store-bought aluminum foil
5) a vertically-oriented and axial (through the midpoint) magnetic field is applied through the lamination

Vertical B field, and horizontal, radial electric current (induced at 16.28Mhz by the eddy current coils) results in the Lorentz force (right-hand rule, recall), creating coherent accelerations of the charged particles in the metal, at the 16.28Mhz rate.

We work at artificial gravity devices, and this was our first design. This is easy work for anyone with an RF background, who is familiar with the Lorentz force.

The waves created by the Lorentz force in the metal layers are:
- coherent (all charged particles accelerating together, in unison, back-and-forth at the 16.28Mhz rate)
- acoustic in nature ('acoustic' does not necessarily mean 'audible' - an acoustic wave is not a transverse wave like a radio wave, an acoustic wave is a *_longitudinal_* type of wave)

Later designs adjusted the working frequency, and the dimensions of the 10-layer lamination so that resonant standing waves became possible

EDIT: the motive and background for why we settled on this, our first design, is extensive and the physics is not obvious. But one symptom was interesting. One of the very early 'symptoms' we keyed in on, were the huge number of witness reports of radio interference of their car radio when a vehicle was near. We recognized that, since a car radio exhibits the same symptoms driving past an antenna next to a roadway, "aha, the vehicle must be inducing acceleration of charged particles" since that is how EM waves are created, and is a way to create enough RFI/EMI to interfere with car radios.

Since the 1940s/1950s reports were filled with this 'interfered with our car radio' symptom, our radio/antenna background told us "the hull is creating noteworthy accelerations of the charged particles in the hull of their vehicle" and the vehicles are creating enough of it to interfere with car radios.

Another symptom reported by witnesses can be created by focused beams of RF - see for example "Active Denial System", a version of which was seemingly deployed in the 11/4/1957 Fort Itaipu incident in Brazil.

Since we found the tech being developed in germany in the 1940s, we figure after they relocated en masse to south america, they used 'demonstrations' like this to extort money from governments, including the 1965 east coast power grid takedown in the U.S. They were developing EM devices in the 40s that relied on focused EM beams relying on the photoelectric effect. It works on spark gaps - including spark plugs - by creating misfires. It will not work on diesel engines, which have no spark plugs. All the witness reports from gas-powered cars of "our engine shut off" when a diesel operated vehicle was nearby reported the diesel-powered vehicle was unaffected.

.

[jerryneel]

Douou have info on an rf amplifier for 13.56 mhz ?

[CreativeHarshRaj]

Can I use this circuit with my 108Mhz FM radio transmitter ?

[hamidbesharati]

Hi .is it pussible to amplify a fast edge squre wave (rise time=30ns) with 10 Vp-p to 100 Vp-p and with rise time being less than 60ns?