Coming from a guy who calls himsel ILLUSTRIOUS PROSTATE lol. Sorry, I couldnt help myself.
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What is so special about a GE superbase anyway?
- Thread starter vswr
- Start date
I installed it myself with the techs instructions. Dropped right in. I'm only a sparky, not a tech, so she kept the instructions basic for me. I was trying to avoid shipping a quite large box of 40+ year old electronics to them (2500 miles each way!) to save some $ if I could, and to prevent damage in transit.
Arrangement was that if I farked it up with my industrial size soldering iron (big blue weller) or if I broke it when I pulled it apart then I'd just bite the bullet and pay the shipping and the techs time. But it worked out great in the end, radio came back to life when I turned it on and its been working perfectly since.
Thatd great and exactly what I needed to hear. If I get the VCO working yhen I can move on down the page if its working. I asked him to send me an invoice for 2.
Yeah I saw that. Nothing in the parts list either. Found it strange that it appeared to have been gone over with what seemed to be a fresh cold solder flow. Im gonna start at changing the VCO to see if I get my 5.5 volts down to 3.6v and take it from there. Thanks for the confirmation on that resistor though.
73s
Correct. Not long after this post I saw that on the schematic and parts list. Thanks!
Well, good news and bad news. I ordered the VCO from the UK, installed it today and the radio worked for about 10 minutes. Then, the transmit light started to flicker and I lost my receive. Is this a common issue? Anyone know what does that? Thanks and happy new years!
Recapped both big boards so far. Tried it out, still has the light flickering. There must be a switching transistor or its associated circuitry thats intermittent. With the volume fully down, i can hear the noise like crackling in the speaker. What a pain in the butt.
Most consistend aggravation with those was the solder connections between top side foil and bottom side foil. They used tiny posts in a hole that completed that top-to-bottom circuit. For whatever reason the solder would develop fatigue cracks on those pads and have to be resoldered from time to time. If flexing the pc board affects performance, look for poor top-to-bottom connections.
73
73
Im gonna tackle that part soon. Im presentlyninto a 142 gtl that is off set by 10khz and I cant figure out whatvwas done to it. Someone put in a whole slew of mods and did a lousy job. Burnt wires, exposed parts, poorly done clarifier that I think fried the clarifier pot and a 10k shif upwards on all channels that I cant seem to fing how it was done. My 19 is on 20, my 28 is on 29, and so on. The PLL doesnt look modified around vmthe pll02a chip and I cant get any channels to tune in right because L13 when adjusted as per sams for 5 volts completely throws everything outbof whack. Any ideas what could have been done to cause this?
73s
Any chance that the slug in L13 is near the rim of the hole in the can? The VCO frequency is supposed to be above the 33.33 MHz third harmonic of the 11.1125 crystal. The difference between the VCO frequency and the crystal harmonic is what gets fed into pin 17 of the 8719 PLL chip. Trouble is, the slug can be adjusted to go below the crystal harmonic rather than above. When the difference frequency gets close to what it would be for the channel you're on, it goes psycho. Increasing the tuning voltage now causes the difference frequency to be backwards. Instead of increasing when the tuning voltage rises, it goes down with rising tuning voltage.
This makes it try to lock, but it immediately kicks the tuning voltage over the back fence. If the slug is near the top of the can, try tuning it a few turns clockwise.
A frequency counter on the VCO itself would be revealing if this is what's going on. Likewise, a 'scope on the tuning voltage can reveal odd behavior that a meter alone just can't.
73
It starts to resonate and pick up channels at about 1/16 to 1/8 down the hole i cant aee any mods that might have been done. Not sure why a drop in 10k would have supported his upper and lower frequency mod either as all it was is 3 crystals and a tuning cap on each. Very basic mod. There is a definite shift here. Even the clarifier drops out at about the 9 o'clock position. Then there is no receive or transmit past 9 o'clock becausevthe PLL wont lock. Not sure if I saw a small pico disc cap soldered up under that tuning coil either. I did notice a cracked slug in a coil further back. I can replace that. Its just odd that the sams calls for 5 volts but I get nothing but garble there. I also noticed that each of the associated mode coils and tuning cap frequencies will not tune up to that 10k difference so the problem has to be around L13. Or, a mod that drops it by 10k. The number seems too exact to be a failure. The radio works perfectly if dialed in to say channel 28, I get on 27, and 38L I get on 37L. Channel 1 is 26.955 and 40 is 27.395. Very wierd.
73s