Look what I found

[Albert H]

Clearing out some stuff this afternoon, I found this:

PLL PRO II Board.jpg

This has got to be about 20 years old!

[nrgkits.nz]

Wow, that’s excellent! It looks quite similar to the pro3 but with obvious differences. Was the output final a 4427?

[Albert H]

That's right. There were three preset divider ICs (that I replaced with the 74HCT4059 for the PRO III), The final stage was tuned with two trimmers,and "out-of-lock power down" was a bolt-on, usually soldered beneath the board. The phase comparator and the VCO were the same as on the later design, but we used FETs for the VCO frequency output to the PLL, to keep the input impedance high, so as to prevent undue loading on the VCO. We had a second FET (on the PRO III) that appeared to go nowhere - just there to ensure absolute balance between the two sides of the oscillator and thereby minimise the ½f breakthrough.

Much of the rest of the board is as you've seen with the PRO III. For its day (designed around 1986) it was a pretty good circuit. The components were all generic - you could buy spare parts anywhere. The board was pretty robust too - the clowns who used blow-torches to solder in the components would usually fry the board, but anyone with a steady hand and reasonably neat soldering could get one of these to work properly first time.

Stephen used to get some abysmally hacked-together boards back from complaining customers, and if they hadn't wrecked the board too badly, he'd put them right for the price of the parts they'd damaged plus the difference in price between a kit and a completed board. Nobody complained about the assembly cost - they were glad to get a functioning board when they'd made a mess of it themselves! The most common faults were ICs the wrong way 'round or in the wrong places, bad solder joints, overheated ICs, or cracked resistors where they'd been yanked down to the board a little too firmly!

There were literally thousands of this board sold over about 15 years. I know of two that have been in continuous service since 1989, driving big valved PAs in Eastern Europe. The only times they've been switched off was briefly to replace the PA bottles when they reached their planned replacement dates.

[woodyalaska]

I still have some unbuilt 40W NRG boards with the BLW60's. Just need the other components. Probably gonna throw em up on fleabay

[nrgkits.nz]

I still have some unbuilt 40W NRG boards with the BLW60's. Just need the other components. Probably gonna throw em up on fleabay

I have all the other components in my inventory plus all the original BLW60’s (two boxes, one now half empty) I got from Christine when the original NRG closed down.