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so no noise out of the speaker? of any kind? maybe a problem in the speaker switching circuit, the external speaker jack. /

I check the bias adjust voltage circuit on these IRF520 MOSFET RF output radios first. take out that T.P. 7/8/9 shorting board. key-up radio in SSB mode, mic turned all the way down, no audio, thus no RF to the IRF520's. then measure the voltage at the gate of the IRF520 Q49. on this radio...

I check the bias adjust voltage on these IRF520 radios first.

so when in FM mode, squelch off, volume up, do you get the usual receiver noise? the rush sound.? and in SSB mode receive, all that usual noise, as a radio with no antenna connected to it..??

looks like your modulation circuit is working. and you get a few watts of carrier output when with J22 unplugged you said. I would look into the 8 V switching T/R circuitry. maybe the 8 V for receive is bad.

OIC / oic / oh I see you have a previous post on this radio. ? ? sounds like there is a problem with the external RF amp.

I have this 99 mounted on a five-foot metal mast buried in the wet Louisiana ground, against an old decking. (so I can play with them "tuning rings") but I had it on a 10-foot metal mast, with the coax at a 90 degree angle running over to my house. the metal mast will do what the ground...

No replies yet? your descriptions go all over the place. I had fun working on one of these over a year ago. found trouble in the modulator (replaced Q67). Then I played around on the 10-meter repeaters up in New York state and Toronto for days from down here. is your main board a 011 or 015...

oh yes, yes, on the 2970. I have a broken 2970N4 here. The extra 400 W power amp is blown up. (aren't they all? this N4 amp set-up looks like a potential disaster!) So bypassed this N4 amp, and now a bare 2970 here. so have the carrier down to two watts or less and barely turn up the mic...

-- and this advice, that everyone here probably already knows, being this is the Prepper Forum. with like-minded people here. Us talking about emergency electrical power with a generator. You must protect your own property, and family first! You can't save the world and help all the...

yes, with this set up, nothing to change in the house. most of the people I know just run generators outside and have all these long extension cords all over the place, running through doors and windows sealed off with towels. and only power their fridge and a window AC. and that video...

I never uploaded a video here yet. and down here in southern Louisiana's hurricane and tornado country. many people have them Generac stand-by generator set-ups here. but here is video from Hurricane Francine Sept. 2024 and a few years earlier after Hurricane Ida I did the same thing. I do...

. I wanted a little amp, with a bias circuit already in it, and to be driven by my Cobra 148. I checked my pile of broken amps that were given to me. (I got that RM Italy amp working, but no bias, sucks in SSB!) Took a look at that DYNAMO amp, and recognized the board as the same as a PALOMAR...

yep, seen this before. I have an AL-811H. but a friend sent me some old used Russian 811's, and they are holding up.

yes, measured just about 2.2 V from MIC 3 to negative. when keyed up it goes to ground. should not mess up the 8.4 V line, or radio would not work. I keep my display on BRT. when changing to DIM and NOR the meter lamp does not change much, but the channel LEDs get dimmer. and no...

and one more thing.. if the same China board. since you are already inside soldering on this board. another known failure point, from what I have read, and this happened to this radio I now own. Resistor R130 to the PLL IC. it needs to be changed to a bigger wattage, a half watt is good...

made in China radio? the only number I have on this board is: . . and the schematic -----

. been reading this post. I have my China made 148 here that had a few things done to it before it was given to me. It works great now. Looks like this same main board as you are working on. So, I just took the covers off to do some comparisons. looks like, by the different soldering...

listen to 6850 kHz AM at nights. Liquid Radio is there, with 10 watts of carrier. homebrew transmitter. heard around the SE and East coast U.S.A. He is on the air right now! ! ! !

with the "HP" it may be one of them transmitter outputs with two IRF520's in parallel, and draws lots of current, and the series modulation transistor gets very hot, 0015 board.