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so are you inquiring about that external RF PA with 8 IRF520 MOSFETs? or the main board, usually having 2 or 3 IRF520's. ?

just drinking my morning coffee here, and took a peek. that circuit adjusted by VR15 is the positive going modulation level from the series modulator ouput. so MM must be for Modulation Meter.

I was checking into this group, starting at 12:30 CDST(?) 17,157.5 kHz But have not been there much in the last year. I am building a vertical dipole, made from and old broken CB ground plane antenna, and a 20 ft. pole. will be fed with ladder line. Should work great 20, 17, 12, 11, 10 meter...

just looked at DTB Radio website. This is funny that he posted: Due to issues with RCI quality issues we no longer stock or recommend any RCI products. We will still do special orders. --------------------------------------------- I like working on them RCI / Galaxy radios. I have a 2950 and...

these are the same radios for the most part. the 102 had the SWAN brand name on it. 103 has the CUBIC brand name on it, the company that bought SWAN. new paint colors, and also the 30/17/12 meter bands added to it.

the CWN filter is described on page 3-7 of the 102BX Service Manual. it is not an optional filter. there is a section of circuitry that is switched in with diode CR103.

. 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...