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With the Palomar in line and off the SWR you see is from an impedance "bump" you are probably getting from the open frame relay inside the amp. Then when you turn it on an you see a very high SWR, that could be from a whole bunch of things. You have ti make sure all the tubes are good and are...

Those resistors appear to do as you say, to limit drive to the tube. The values could be changed depending on the available drive from the exciter if it is fixed and cannot be adjusted. If you have an exciter with an adjustable RF drive output you can eliminate those resistors all together and...

Make sure D16 is not shorted in the power supply circuit. That can cause you to see grid current in transmit with no drive. If it is shorted you may see the plate and grid meter tracking the same way on the scale. You can only check it with one leg lifted off the board. Replace it if it is...

Sounds like 1200 watts output is really stretching it on AM. Its not unheard of to get 900 watts pep SSB out of an SB-200 as a mono bander, but 1200 AM is pushing it on AM. With enough drive it might but like you say, for how long.

That's great Nomadradio!! It all makes perfect sense. I guess looking for an SB-220 all done up with those mods will be hard to find unless someone is doing it. Thans for the insight.

OK fine, so then what box should be considered if swinging up to 1500 or so should be considered? Thanks.

The Clipperton, SB-220, SB-200 are no damn good on 10 meters anyhow. None of them make good power and easy tune up on 10/11 meters. That's why a dedicated amp for this band is more desirable and hence should have an appeal in price over it's stock performance on 10/11 meters.

Thanks, I assume that the market would be for 27 mhz users. That said, I would think a 1500 watt amp for 27mhz is worth more than $500.

Yes, that's right. Carrier about 250 with modulation to peak of 1400-1500. Now what is it worth?

Thanks for the reply. Maybe I should have said that the 1400-1500 watts output is un-modulated. So I guess that would be the modulated peak power. That seems about right for 4 of those tubes in a single band amp. I don't think the PS or tank circuit should be a problem. It's got to be worth...

Can anyone tell me what a nice Dentron Clipperton L converted solely for 10/11 meters is worth. It can dead key about 1400-1500 watts output. Thanks.

I think the Hammy AM'ers call it "downward modulation". If you look up that term you will get a better response from Google. The CB'ers call it "back-swing". Kinda like the CB box builders calling a Variable capacitor a "TUNER". Likewise, if you Google Variable capacitor you will get the...

Crimp connectors are really great for foam coax but soldering isn't bad on the hard type of center conductor insulation types of coax.

No, in a multi capacitor string of electrolytic caps in a power supply, the caps are usually in series. Just about ANY sweep tube amplifier will no have more than 900 volts on the plates. It is always a good idea to have some head room so use enough caps to keep you well above the operating...

That seems perfectly normal.

Tube amplifiers require between 21-32 uf total capacitance. If that amp does not have a step start, which it probably doesn't then I would stick to about 21 to 25uf total. So how many caps are in there? Two? Just multiply the amount of caps TIMES the desired total capacitance. So if you...

To get the most from either 3-500 or 4-400 tubes (in an sb-220/1) you are better off directly grounding the grids. Remove the capacitors and cap/chokes from the grid pins and run a large wire or coax braid or copper strip to ground each grid pin directly. Now either tube you use will make...

Change the -120vdc PS capacitor. It is probably leaking.