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Dam, this sucks, hope Jeff gets a few decent years of retirement. I just ordered SB220 parts a couple of months ago from him. Hopefully someone else keeps it going so parts are available for these old amps.

Thank you nomad for answering my questions!

The tube duct diameter is slightly larger than 3.25, so I'll use that dimension to be conservative. The velocity measured with my wind wizard 1/2 inch away from the tube duct outlet is 3.6 MPH, 6 inches away from the duct outlet velocity is 2.8MPH so again I'll use the conservative number...

The temp sensor is directly in the air stream off the tube so the temperature likely isn't dropping much at all. I don't know the volume of air, I'll measure the velocity tonight and calculate the CFM. It's the stock AL-1500 blower on high speed.

What is the maximum safe exhaust air temperature I should see off of a 3cx1500a7 in a AL-1500? This amp has tube stack mod to keep the band switch and tank circuit area cooler, plus the fan is on the high speed setting. Also running @ 4000 volts on the plate with the upgraded 10 capacitor...

They will do impressive meter numbers, I have never seen a C box that wasn't starting to spread out by the time it reached 150 watts per pill.

There is a stud mount version of the Performer 5000, I have one and posted a link to it above. RG58 will handle far above 400 watts, I have run 1.5KW through it for extended periods. (If you want zero coax issues in a mobile use RG400) The real limit is mag mounts, I have never seen one...

Definitely. I drive a 8 pill with 90 watts and that's pushing the 8 past linearity.

That's not going to last long...

I run the antenna in the link below on my mobile with good success. It's the normal 3/8" stud mount so it will fit on any 3/8" mount. Mine is on a well grounded breedlove puck mount. Swr is very good, forward power is 900-1200 watts in the mobile depending on alternator temperature and...

Posting this in case anyone else runs into an issue of the ATR-30 tuner reflect meter pegging at higher power levels. I think I have resolved the reflect meter hitting the stop peg when running at legal limit. I noticed that any time I was on a band that the transmitter capacitor was more open...

I go by 1340 NEBRASKA, 1340 NEBRASKA mobile, or WDX134 on 16 LSB. I have my extra class amateur ticket, but won't share that online for op spec. 1340 is the displacement of my Hayabusa.

Yes, there you can have an antenna matcher (tuner) between the SWR meter and antenna. My current equipment lineup is: radio - grounding switch - linear - SWR/power meter - antenna matcher - lightning arrestor - antenna. If all equipment in line has a characteristic impedance of 50ohms and the...

The meters on my sb 220 have the diode protection already on them. Thank you again everyone for helping me get it running again! I appreciate the guidance!

I am having an issue with the reflect meter jumping up on my ATR-30 tuner anytime the forward power is near legal limit. The tuner and antenna system are not arcing, I have heard that before when it was badly mistuned. I'm thinking the meter diodes are breaking down. Also it seems like it is...

That would be a good work around for the encoder issues all these radios seem to eventually have. Hopefully someone will do a how to.

Thank for this information! I'm pretty sure the meters have the diodes already on them, I'll double check the next time I have the covers off.

To update this: this sb 220 is running good again. A new HV capacitor bank and board is what it took. Thankfully the meters didn't get hurt when it went bang. All of the rectifying diodes also tested good. 70 watts drive makes 1500+ out on the lower bands. Thank you everyone who replied...

Lots of questions... The matching range or the total inductance / capacitance isn't mentioned. 1KW tuners are typically 1KW into a 3:1 load, and far less into a none resonant load. I went back to a manual ATR-30 tuner as it is far more robust than any auto tuner. There needs to be a true...

Thanks for the reply. The HV capacitors installed were already the 210uf 450 volt US made ones from Harbach. Pretty disappointed that one cap already shorted with less than 10 hours of talk time. Hope the failed cap was an anomaly.