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This radio is ground-breaking in that it is NOT a $1200 Icom and Yaesu and yet it has many of their features, and sometimes does things far more expensive radios cannot.? ? Instead of using $15 final amplifier MOSFETS (which would be much easier to design for!) it uses $1 MOSFETS. The ICOM 718 went through at least THREE different designs for it output power stage over its course of years (and possibly more).? ?I have worked on one with bipolar transitors and another with mosfets!? ?Wonder if their owners even knew? The VHF parasitic oscillation caused a lot of problems, and required redesign of the T/R system as part of the eradication.? ?That resulted in an elegant diode-switching system (where Hans is said to have helped out greatly) and that made this an even better radio.? ?? I think there are still a few "gotchas" in the diodes connected to?+12 without series limiting resistors -- but if you never venture in there with a probe, they will do just fine.? ? Many of us prefer to change out the mica insulators to Aluminum nitride and at the same time, polish the matching surface of the heatsink.? ?? I remember when some of the most expensive radios on the market were found to have huge linearity issues -- very embarrasing?-- and the company came up with fixes eventually and solved it.? ? The use of a LINUX COMPUTER as the controlling microcomputer is new and different for many of us, and that has both advantages and disadvantages.? ? I can't remember if the software includes "foldback" on the power but if it doesn't, that could easily be added.? ?What I think we've generally realized is that on a 12V supply, going to 100V MOSFETS gives a great level of protection against poor SWR.? ? The GATE was another weak spot and in recent designs, Ashhar has chosen to adjust the gain around to reduce that risk, and he has also in some cases added TVS protection diodes.? ? ?? There is a little 3-mosfet power switcher that we think has a "gotcha" built into it that can be fixed by adding one resistor and for the adept, that is a good idea.? ? Past that, it is an incredibly fun radio!? ?And cheap enough that I can own TWO of them!? ? It got me onto 2-meter SSB for the very first time (with the addition of a transverter) and the ability of the microcontroller to run other software at the same time is helping me begin to forage into satellite communications, something I've never done before.? ?? It is NOT the radio for "appliance operators"? who are better off teething on ICOM or YAESU (I prefer Icom).? ?There are all kinds of people in ham radio and not every radio fits every person, at every stage of their growth! What a fun radio! 73 Gordon KX4Z On Sat, Mar 1, 2025 at 7:05?AM Evan Hand via <elhandjr=[email protected]> wrote:
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