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Hey, I tried to put the NFB into a solid state amp once, being used as a driver for commercial HF SSB. It was not so easy. Assuming a pair of NPN transistors delivering 100 watts at 30MHz, running

tnx, Tony. Since adding RF-NFB to a transistor amplifier is as simple as adding unbypassed R to the emitter leads, it puzzles me why Ham transceiver manufacturers don't wake up and start building

R L Measures wrote: <snip> Tom says the following: "IM3 levels of -30 dB are really very poor. An old KWM2 I tested was -47 dB using ARRL standards. Compared to something like an IC-756, the Collins

Well right now I dont have any "official test lab" figures, however W8JI has measured (if you trust him, I do in this case) -47 dB. Myself I have measured a KWM-2 compared to a FT-1000D, KWM-2 was

What is the total IMD of a KWM-2 ? R L Measures, AG6K, 805.386.3734 r@..., , rlm@..., www.somis.org

Jim, I use the 10 kW version from Array Solutions. Checked it with the scope on the R&S dummyload @ 6 kW on 80, 40 and 20. Seems to be right on the money. Cheers, Dick

As far as I know a Collins KWM-2 / SM2EKM ------------- R L Measures wrote:

If I recall, they have the QRO brand of amps set up this way, or I seen one being modified I can't remember which. All they did was mount a button type thermostat near the tube. Seems to me though

even I already had a monster blower on hand when I put my YC-156 amp together. I drilled a hole in the wall, and ran the cooling air thtough a 10 foot hose from another room. I hear no more noise than

Two speeds are good, Tony, and proportional speed control with a DC- brushless motor is better yet Tektronix was doing this 30-yrs ago. R L Measures, AG6K, 805.386.3734 r@..., , rlm@...,

You missed the point: A fuse that creates a metal vapour arc when it opens does not adequately limit peak-I until the arc is extinguished. This is why 250v 3AG fuses are bad engineeri

R L Measures wrote: You can get a 1500 RPM blower from Dayton that will cool the YC-156/179 and not be loud. They've got a nice two speed blower that'll do even better if you sense the cooling air

One advantage of an 8171 is that a quiet 1700rpm blower will cool one VFB on SSB. R L Measures, AG6K, 805.386.3734 r@..., , rlm@..., www.somis.org

Excellent chortles, Tnx, Peter R L Measures, AG6K, 805.386.3734 r@..., , rlm@..., www.somis.org

Yes Probably 90% of 'em will tell us that heavy straps have zero L. My dipmeter says the 3-500 grid resonance frequency is c. 1MHz higher grounding with caps instead of straps.

### Yeah... at 60 hz...... 50hz if u live in EU. Later > >

protect the HV- transformer any better than a circuit breaker in the primary. cheerz ### Don't get sucked into this arguement Frank. ### Rich..... seen any 10-100 kw broadcast stations... with NO HV

vapor arc that had a v-drop of c. 20v during the period when it should have been limiting current. #### Rich, obviously a .82 ohm resistor is not gonna limit current. It's in there as a HV fuse..