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on your other SB-220, the problem could be in the switch contacts for the metering circuits. also, the band switch contacts go bad. For the local CB guy here, we took out the band switch and just have a 27 MHz output circuit. also, when Zener diode ZD1 is blown up, and either shorted out...

I was using and testing a SB-220 that I repaired from a local CBer, on 17 meters. It was sparking sometimes also, just like yours, so I did the following to stop this problem, as in any of these tube amplifiers: after tuning and peaking the Pi-network output, turn the load capacitor to a lower...

from the infineon.com post - "Pre-sale Counterfeit Verification" "Additionally, we do not support the sale of Infineon products via eBay or similar auction houses or any other below market source." https://www.infineon.com/cms/en/product/promopages/counterfeit-products/ "Infineon products...

over a year ago, this local CBer gave me this old Antron 99, that has been painted, and it suffers from "erectile dysfunction" as the thread is stripped up at the top section. I just slapped it up on at this 4 by 4 wood pillar from an old decking in my backyard, on a five-foot section of metal...

from the KIO Tech Hexbeam site. and I know people that did this. "Another approach is to wipe off the dust and use a spray can of Rust-oleum Universal which is a combination of primer and paint. It comes in flat black as well as other colors and a single coat is probably sufficient."

SuperLid, I noticed the Cubic Communications transmatch in that picture. I do repair work on the Astro 103 and 150.

. hey, TimmyTheTorch. I was trying to message you. I am trying to get my hands on more or these MOSFET RF output radios that people have thrashed on, and given up on repairing, so I can do some more tests n changes. Maybe get me a good repair customer base. I will send it back repaired. These...

my 5 cents worth (remember, todays inflation). I have a 142GTL that I got back on freq for SSB use. a "PI" made unit. date on the back.

yes, these amplifiers have "lame keying circuits." most of the amps I get, the RF key circuit is blown out, and has an attempt at repairing it. I put in a more robust circuit, that will not blow out.

I have a few of these 250's here. This RF key circuit has been messed with in both amps. One is keyed up all the time. I traced the diagram out and it makes little sense. So did this circuit ever work? AM and SSB? These amps seem to be OK. The transistors are biased, unlike many of these...

another thing on this radio set up. I got it after it was worked on before. It was blowing fuses. Regulator/mod transistor was all shorted out, and also found the short of a solder blob between solder joints at one of the IRF520's from drain to ground. I removed them 5.6 V zener diodes...

it is a "swing machine." that is because the meter on the radio is reacting to the positive going signal. so it shows swinging upward. but the overmodulated signal is also going to zero in the other direction. cutting off. going to no RF output. as in - "crank it up and whistle, then the...

Connex 3300HP Galaxy DX55HP circuit EPT360015C - I got my hands on a Connex 3300HP to repair. I see that many have problems with this radio, and all those other IRF520 MOSFET RF output section radios in general. - I only have worked on a few of these radios, to get them to work in SSB...

hey, hold off on your repair attempt. . . I have a Connex 3300HP to work on. I got it working, real good. but I noticed about 5.7 amps from the power supply during key up with 9 watts RF out. this is not good. and that "regulator" transistor got so hot, and it smoked and blew up!!! The...

well, now your radio is all screwed up. but you can set the IRF520 bias to 20 mA per device. as long as they are starting to conduct. but check the bias voltage adjustments. in SSB mode, mic turned off so no audio, no RF. with that mirror/shorting board in place, key up, and turn each...

I see the 010 schematic. about the same in the IRF520 RF output section, and has the 100k resistor ("C291") in the driver bias adjust circuit, so you can adjust properly. and again, in AM mode, with a dead carrier, with your 4 watts out, what is the voltage from TP7/8/9 to ground? should be...

so you have the IRF520 transmit section it sounds like? the "0015" board.?? "driver and finals adjusted to the correct ma" I was just working on a 2970N4, and on the main board, with the three IRF520 design, added the missing 100k ohm resistor so the driver bias current can be set. (I have...

me drinking some hot strong coffee all early morning here. but you probably have this: https://cbtricks.org/radios/galaxy/dx55v/dx55v_pll_adj.htm check the signal freq at TP-3 the PLL OFFSET OSC section. do you have a signal at IC-5 pin 2 ?? CB ch. 1 should be 2260 kHz the binary code...

Yes, sounds like PLL/VCO problems. I had a few radios just like this. to start: at IC-5 pin-1 check for around 7.5 volts. check the voltage at TP2 and measure if it changes when going from CB ch 1 and jumping to ch 40. check signal at TP3

I have this website bookmarked, on this DDS subject. from Brazilian guy.. https://www.ddsvfo.com/ .....