Search results

. check diode CR103 on the Exciter Board. the CW filter is some added crystals and other circuitry. these PIN diodes fail all over this radio. especially in the preselector board. they can be replaced with 1N4148's.

so what problems are with your CP2000? the mic speech compressor? I work on Cubic Astro 150 / 103 (Swan 102) radios. And in the past SGC marine band SSB radios. they have that Don Stoner guys thoughts inside them. great SSB stuff! similar circuits here and there in those radios. I just got...

mounted the 8.5 volts at the collector of transistor TR41.

and also monitor the 8 V transmit line someplace. if it drops, then modulator drops.

been following this thread. it is fun to make these transmitters work! so Hawkeye351 did you get this radio to transmit without the dropping power problem? and any modulation problem? here is what I would do. disable that AMC circuit. keep D92 or R249 cut out. or adjust the pot so it does...

from eBay: WAVETEK 3000. to 520 MHz. . ha ha! we did the same thing while bored at a lab, at various employers in southern California. these WAVETEK's were all over back then. (1978 era) Connect to an antenna. Modulate it, or just turn the internal tone modulation. would jam or talk over...

yes, these oscilloscopes have a linear amplifier section following the probe. calibrated gain sections. to make it viewable on the CRT. I have 3 or more old CRT display scopes around now. two were given to me. you can get them cheap/free nowadays. Find an old B and K, or Hitachi scope...

Here is how I measure and adjust an oscillator frequency without loading down the circuit. I have my frequency counter connected to the vertical output of an oscilloscope, using the amplifier in the oscilloscope to boost the level to my counter. Turn the scope sensitivity all the way up and...

this is new to me. what is this "VFO windup" circuit about? ? causing your frequency to sweep. what is the application? on one radio I disconnected what appeared to be a faulty roger beep board. I was told it was working normally, and put it back in circuit. I was told it is a "duck fart"...

. Yes, I remember back in the Los Angeles area as a kid in the 1970's. Kraco auto electronics was sold at K-Mart. Maybe also at White Front stores. Maybe Zody's. (the memories of them places!) That there gave their products a stigma right from the start. Us kids would get our fake "waffle...

I have my old A-99 mounted to a five-foot mast with the coax going at a right angle to my house and radio room. I will put it back on a taller mast again. Works great on "27 MHz CB" 29.000 MHz AM and 29.600 MHz FM. the mast / radials / CP are the other half of the antenna. the antenna...

keep this thread from 2008 going. :) these types of tools.

I worked on an older Saturn with the 013Z board in it a few weeks ago. I had just over 40 W PEP output SSB. Set it to 10 W carrier for AM. works good. I posted my RF out bias circuit change. for the weak receive, tune up the receiver front end RF amp coil L6. it may have been messed with...

got a 939 for repair. it is modified for "TX audio direct injection" on the back of the radio, and had a "golden screwdriver" turning this and that. :oops: It worked but ran so hot I was told they had to put a fan in place of the speaker to keep it cool. :mad::mad: so yes, the "520's" bias...

playing "armchair technician" just checked out the schematic to that radio. so with a regular mic plugged in, does the PA work? loud audio there? and receiver audio in the speaker? If yes, then maybe a problem in the ALC circuit. for TX modulation, and that audio ALC circuit. turn RV102 to...

brandon7861 says - - "*Someone* should redraw that AGC path and the detector circuit in a way that makes it easier on the eyes (and brain)." yes! much agreed. it is hard to see clearly on the schematic. but on the old 2970 I successfully got working on strong SSB signals. I found, I think...

just got home from a long day at work. yes C73 on the 14B board, going to the product detector. for TP6 I added more RF osc signal on this older 2970 with a 013 board and the cap is C90. I could see on the scope that the carrier level was low, so put in a 100 pico-F and strong SSB signals are...

transistor TR30 should be good. don't mess with it. TX in SSB and AM is working. you can see that the AGC is working. the S-meter is moving is a good indication of that, and it works in AM receive.

transistor TR30 should be good. don't mess with it.

hold everything.... the SSB receive signal in this design takes a different path at the end. there is extra gain and transformers to tune (L13 and L14). and AGC is separate at the end. there is not enough carrier injection from the transistor TR30 carrier oscillator to the SSB receiver...