If one are not satisfied with the result or you would for any other reason generate the original circuit, it is sufficient to remove everything and recover the track. The installation (see photo) is not difficult and you need only to cut a track and solder the components. I used a 4C6 toroid in stead of the FT50-43 type.
#Image mixer version 1.5 mod
However in practice showed no noticeable difference, so I did the mod with the more available J310. Indeed I have tested the amplifier with a vintage P8000 and P8002 FET. Purists will note that a high current FET could be a better choose. Unfortunately my test gear was only accurate to about 45 MHz. That improves the flat load for the mixer and a measurement showed SWR ≤ 1.7 from 1.5 to 45 MHz. Too much gain in this set leads to oscillate during transmit, therefore the output is loaded through an attenuator with standard resistors. The circuit with a grounded gate provides proper termination to the diode mixer and the input SWR at the source is flat. The data was actually collected from the original boards. Note the different capacitors and colour of 元's slugs. The modification is applicable for all PC-100A to 100D-PC boards. The design is in fact a buffer between the mixer and the tuned L103. This J310 FET post mixer amplifier follows the front-end mixer without having to use a diplexer. I have tested a number of circuits see below: This can be achieved with a so-called duplexer (fig»), but also with an amplifier with broadband input impedance of approximately 50 ohms. A third simpler design for a post mixer amp & spectruanalyzer image of input SWR & image.Ĭurrent saving LED lightning for dial and meter, homemade Alu finger dimple.Īn optimal operation of a double-balanced diode ring mixer can be improved if the IF port is loaded with a non-induction impedance of 50 ohms.
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