My second thread on here (and the first has garnered no response as of yet).
So I was gifted a 959 that was "done up." IE: blue lights, extra channels, echo board, and dual finals.
One big problem; this thing originally pushed a max of 10 watts out of 2xIRF520N. It was readjusted to make 20 watts...so I assumed something isn't right.
My background: I have spent some time (about 15 years) working on guitar and amp repairs (primarily tube). I don't have an oscilloscope or signal generator currently, but I have a decent DVM.
That said, here are some things I've noticed:
1.HORRID solder jobs; broken joints, solder balls, splatters, cold joints, no tinned wires for the mod board add-ins. I spent a good hour just fixing that.
2. A replaced power MOSFET, but only 60 watt. I replaced that with a 100 watt version.
3. Stock audio amp. Replaced with an upgrade.
4. L31 on the board was pretty mangled/erratically wrapped. Looks like an 8 turn with one wind going under the rest...does not look stock.
5. With so much solder, one of the finals had the drain shorted to the source. I'm going to assume if it wasn't burnt out, that was probably the issue.
6. All that really happened was a jumper was run for the drain of the extra final, and a capacitor in C212 spot.
7. No VR11 for second final biasing.
8. D90 looks to be replaced, but facing the wrong way vs. the diagram I've found online, and no D91 is in place for the second final.
9. L33 (resistor with a bead core) was removed, and replaced with just a resistor on the underside.
10. What looks like a PPE resistor/diode mod in shrink-wrap. This radio came from Rolling Radio from what I gathered (I am not the least impressed).
11. A tantalum capacitor on the underside linking other caps topside. Since it's in the signal path for the finals, I'm having to ask why someone would use Tantalum for that.
The goal: since this is my first foray into CB mods, I'm hoping to get this thing back to semi-stock (remove PPE and tantalum cap) and continue on with (actually) making it dual finals. The downside is no O-scope or signal generator to really test it. Hopefully I can find a local tech with these things to help me out.
While I am grateful for the gift (seriously cool to start out with this), I am rather unhappy with the lack of quality work from a radio modification business. I'm by no means a radio guy, although I've had my fair share of discussions about amp design and building (mostly tube) for high gain guitars.
This is kind of a work in progress/complaint page for me, but I'd love any meaningful suggestions. If you people want pictures, just ask, although I don't have much of the before pictures.
The "Too long didn't read, or TLDR" section:
I was given a modified 959 that is rather horked/butchered, and would love some pointers, as it has a few issues.
Thanks for reading.
~Cow
So I was gifted a 959 that was "done up." IE: blue lights, extra channels, echo board, and dual finals.
One big problem; this thing originally pushed a max of 10 watts out of 2xIRF520N. It was readjusted to make 20 watts...so I assumed something isn't right.
My background: I have spent some time (about 15 years) working on guitar and amp repairs (primarily tube). I don't have an oscilloscope or signal generator currently, but I have a decent DVM.
That said, here are some things I've noticed:
1.HORRID solder jobs; broken joints, solder balls, splatters, cold joints, no tinned wires for the mod board add-ins. I spent a good hour just fixing that.
2. A replaced power MOSFET, but only 60 watt. I replaced that with a 100 watt version.
3. Stock audio amp. Replaced with an upgrade.
4. L31 on the board was pretty mangled/erratically wrapped. Looks like an 8 turn with one wind going under the rest...does not look stock.
5. With so much solder, one of the finals had the drain shorted to the source. I'm going to assume if it wasn't burnt out, that was probably the issue.
6. All that really happened was a jumper was run for the drain of the extra final, and a capacitor in C212 spot.
7. No VR11 for second final biasing.
8. D90 looks to be replaced, but facing the wrong way vs. the diagram I've found online, and no D91 is in place for the second final.
9. L33 (resistor with a bead core) was removed, and replaced with just a resistor on the underside.
10. What looks like a PPE resistor/diode mod in shrink-wrap. This radio came from Rolling Radio from what I gathered (I am not the least impressed).
11. A tantalum capacitor on the underside linking other caps topside. Since it's in the signal path for the finals, I'm having to ask why someone would use Tantalum for that.
The goal: since this is my first foray into CB mods, I'm hoping to get this thing back to semi-stock (remove PPE and tantalum cap) and continue on with (actually) making it dual finals. The downside is no O-scope or signal generator to really test it. Hopefully I can find a local tech with these things to help me out.
While I am grateful for the gift (seriously cool to start out with this), I am rather unhappy with the lack of quality work from a radio modification business. I'm by no means a radio guy, although I've had my fair share of discussions about amp design and building (mostly tube) for high gain guitars.
This is kind of a work in progress/complaint page for me, but I'd love any meaningful suggestions. If you people want pictures, just ask, although I don't have much of the before pictures.
The "Too long didn't read, or TLDR" section:
I was given a modified 959 that is rather horked/butchered, and would love some pointers, as it has a few issues.
Thanks for reading.
~Cow