Welcome to the station of

WB9ECK

This transmitter is an entire transmitter and not just a class C plate modulated final stage like most folk do and "call" it a transmitter. All self contained without any outside help from a plastic or any other store bought radio. I built this entire transmitter myself by hand one piece at a time.

The heart of the "transmitter" is a 6AG7 crystal oscillator. The crystals are all built in and can be switched at the flick of your wrist. The 6AG7 drives a 6L6 buffer tube. The 6L6 buffer drives a 572B neutralized power triode driver tube. The 572B drives a 5762 neutralized RF power triode final which is high level true plate modulated (not screen/plate modulated) which would be the case if a multi-grid tube (tetrode/pentode) was used in the final RF amplifier stage. One other major advantage of the final RF stage is that it uses grid leak bias only (no fixed bias). This gives the modulated stage maximum linearity/fidelity on voice peaks and troughs. I am also modulating the driver stage (572B) the same polarity as the class C final which allows the bias/drive to track the modulation envelope greatly reducing distortion. This configuration allows the “operating angle” of the 5762 class C final to remain constant. The speech amp consists of a quad of 807s wired in push-pull/cathode follower configuration to directly drive the grids of the 833A final modulator tubes without the use of a driver transformer. The 833A’s are biased into the class AB/2 region. I am using approximately 12 DB of inverse feedback in my audio chain that also increases fidelity.

This transmitter could be described as a triband/monobander as it has independent networks that are switch in and out in their entirety (no tuning of the exciter stage after changing bands). This allows me to band hop quickly. I can change bands and be ready to roll in about 20 seconds. It works 160, 75 and 40 meters. I designed my pi network to load into any load from 20 up to 700 ohms (icing on the antenna) so that the use of an outboard transmission line coupler would be redundant.

This transmitter is handmade from where it plugs into the wall to where the antenna screws into the back. All of the RF inductors and RF neutralization/input transformers are home made or hand wound on whatever material I had available to me that would work. The RF deck is my own design as well as the self contained power supplies. I have separate adjustable high voltage power supplies for the RF deck and the modulator so you can optimize the audio to carrier ratio. This transmitter is a real pleasure to own and operate.

Here is a shot of the RF deck and exciter.

Don't those modulator tubes look awesome?

Here it a picture of it before it was stained.

Click here for more pictures...

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