2018-10-13

Using the PA for both HF and 6/4m transceivers.

I have a IC-7300 covering HF, 6m and 4m, and a IC-7600 covering HF and 50MHz. I would like simultaneous use through the PA of both transceivers to a R-6000 antenna and a 6m 1/2 wave antenna.

How to proceed? Here is my idea. Between the radios and the input of the PA I can use (lazy as I am) a commercial diplexer, like the CF-360 from Comet or the MX-62 from Diamond.
The problem with using those at the output of the amplifier is the limited power they can handle. 600W PEP or about 200W continuous. Not exactly fitting for the 1kW capability of the amp.
Looking a bit around on the net I found this : https://www.ka6wke.net/hf-vhf-diplexer , describing the use of a IC-7300 with an HF antenna and a 6m antenna with a home construction diplexer. There is a design that I could use, albeit with components capable of withstanding the higher power.
What about 4m ? At the moment of writing this, the power limit for 4m in Denmark is 25W, so the PA is not really necessary. If the limit goes up, I might think of a modification to the existing PA, or using a second transceiver for 4m and building a separate amplifier for 4m.

Next step is to find those components.

At the moment the amp is running low power, 200W, with a CF-360 at the output, connected to a vertical 1/2 wave 6m antenna, at the VHF port and the R-6000 at the HF port.

Now, here is the question some will ask :Why use a separate antenna for 6m when the R-6000 does 6m, too ? I have compared the two antennas, and I find that the 1/2 wave antenna for 6m performs far better than the R-6000 on that band. Further, since I do not intend to set up a HF beam, but at a later stage I do intend to have a small 6/4m capable of accepting the full power of the amp, so here we go !
I may design some high voltage capacitors , maybe made with PCBs, if I can not find some suitable for the 1kW filter I prefer to design for higher power than I intend to use, so I can avoid burnt components and/or equipment.

Oh, Boy ! Yet another project added to the pile ;)

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