More rare NRG gems

[teckniqs]

After my recent trip to the NRG Kits museum with Sinus Trouble I managed to grab a few pictures.

Should look familiar:

nrg1.jpg

Original PLL Pro I experimental prototype:

nrg2.jpg

Original 1w VFO prototype:

nrg3.jpg

[teckniqs]

Original 1993 VFO:

nrg4.jpg

Another original 1993 VFO:

nrg6.jpg

VFO with stereo encoder:

nrg8.jpg

[teckniqs]

Original Steve Moss audio limiter (1988):

nrg7.jpg

Steve Moss Band 3 link conversion:

nrg5.jpg

Close up of modifications:

nrg12.jpg

[teckniqs]

Original Steve Moss stereo encoder (1994):

nrg11.jpg

[sinus trouble]

Being a massive NRG fan, its great to see all this old gear and how it all started!

[MiXiN]

Being a massive NRG fan, its great to see all this old gear and how it all started!

+1

Nice one for the images mate.

[Shedbuilt]

One from the vaults. Looks like the finished version of a part populated board in one of the earlier pics.

tx2.jpg

[andrew_kits]

nice images !

[Elopid]

One from the vaults. Looks like the finished version of a part populated board in one of the earlier pics.

tx2.jpg

Hi Shed, I'm just wondering was the power amplifier added later on or is it original like the rest? Elo

[Shedbuilt]

One from the vaults. Looks like the finished version of a part populated board in one of the earlier pics.

tx2.jpg

Hi Shed, I'm just wondering was the power amplifier added later on or is it original like the rest? Elo

That one was a complete 10W rig from Mr Moss - bought in about 1992.

[teckniqs]

Looks like there's a cap or trimmer missing going down to ground after the first coil out from collector of output device?

[Shedbuilt]

Looks like there's a cap or trimmer missing going down to ground after the first coil out from collector of output device?

Nothing missing. The inductor is in series with a trimmer. The shunt trimmer (to ground), is the other side of the series trimmer. The junction of the two trimmers is the 50 Ohm output to the filter; kind of tapped C. It's the same type of output network as the one Sinus is working on.

[Albert H]

NEVER call him "Steve"!!!

He was always "Stephen", even to Christine.

He and Christine were very kind to me back in the 90s, when I went through a rough patch. I helped design some of the PCBs. We always used the DOS version of EasyPC - I still have his library files here somewhere, which include the component shapes that he created (including the "handbag" that was a push-fit jumper which looked like a tiny handbag when unplugged from the board). We found that it was relatively easy to design single-sided boards that worked well at VHF. The trick was to keep the track lengths of anything with RF on them as short as possible, and use as much groundplane as possible.

When he was sued (by that scumbag Paul , who used to be his business partner) for using his own designs I redesigned the Pro III stereo coder, adding mono / stereo switching with a red and green LED to show mode, and a nifty little addition that guaranteed which input would be left and which would be right. The "competing" coder from "Veronica" (Stephen was "NRG" by this time) came on with random channel inputs. The layout of Paul's version was so bad that the 4864kHz crystal signal appeared on the output, giving nice big spurs 4864kHz either side of the carrier!

The 4 Watt version of the Pro III was a work of art. I added the out-of-lock power down bit to the board, and he redesigned the driver and output stage to be totally broadband. It actually has slightly rising gain across the band - 4 Watts at 88MHz, 4.6 Watts at 108MHz was typical - to compensate for the slightly drooping gain against frequency characteristic of the BLW60 that he used for the 40 Watt output amplifier.

I suggested the use of the 74HC4059 as the programmable divider, which would allow the use of BCD-coded rotary switches for frequency setting. We prototyped an add-on board for this, but it never went into production.

I also came up with a cheap frequency counter circuit to display - on 7-segment LEDs - the output frequency of the rig. This was designed for use with the VFO stuff as well, and would have been a cheap way of checking the setting of the oscillator. It took half-frequency in and (effectively) divided it by 50 and displayed the result - with a "moved" decimal point!

I came up with the Pro IV stereo coder, with the synthesised 19kHz pilot and over-sampling.

We were also working on the Pro IV exciter when he fell ill with the first stroke. We'd got rid of the trimmer in the VCO - by means of switching in capacitors selected by diode switches and controlled by the frequency setting switches (using those rotary switches by this time).

There was also a linear power output adjustment, with a power sampler, so that the board would give the same power output right across the band. We were contemplating using the 2SC1971 for the final, to give about 6-8 Watts across the band, and I'd designed a nifty aluminium angle heatsink that went right across the PCB and took the voltage regulators (there were two in this version), the power control transistor, and the output transistor. The drive only needed to be about 520mW, so the 4427 driver didn't really need a heatsink, but we included one as that was what people would expect!

The heatsink was earthed, and also provided mounting holes to assemble into a case. It also gave screening to the output filter - separating it from the rest of the board, thereby ensuring no RF feedback problems and a cleaner output.

We persisted with the dual-transistor, half-frequency oscillator, but used a more sophisticated multi-pole high-pass filter to remove the fundamental. Stephen was convinced (and I was largely persuaded) that half-frequency generation would improve stability and prevent RF feedback, especially when in the same box as a large PA. It also gave the advantage that we could continue to use ordinary logic ICs instead of expensive pre-scalers or all-in-one PLL chips. Stephen insisted that all the components had to be off-the-shelf - available anywhere - parts.

I'm going to have a clear-out of my cellar over the next couple of months, and should find a few NRG goodies. There should also be some documentation of the Pro IV project - if I find it, I'll put it up on here (or at least provide links to it on Dropbox).

[teckniqs]

Welcome back, Albert.

....My sincere apologies, only I've only ever heard him referred to as "Steve" and never "Stephen".

I'm sure many of the forum members, like myself, will be glad to have you back on board and I highly appreciate you taking time out with your informative and somewhat interesting reply.

[Albert H]

Hi Teck

Back again, and bad as ever.....

I've been out of the UK for a while, and sort of lost touch with things. I'm back now, recuperating from a couple of operations, and taking the time off to design some new gear.

I'm working on a "Cheirix"-modulated Medium Wave box at the moment for the 3rd world "Parish Pump" low power stations. It uses simple DDS for the carrier generation, and Class D for the power amplifiers. It's designed to work from car batteries, and I'm getting 20 Watts carrier, 77 Watts pep (so a tiny bit under 100% modulation) from 13.8 Volts.

The big problem is the output match. It has to be able to work into all sorts of "less than ideal" aerials, without setting the PAs on fire! If the load is 30 - 70Ω, there's no problem, but things get trickier outside that range!

[Premier-Carousel]

Hi Guys,

It was nice to see the pic of that VFO with my old partner in crime Tim's name on it. He like Stephen also sadly no longer with us, and both sadly missed. For anyone wondering Tim and I were behind Premier radio/Carousel radio in the NW way back in the early 90's, the early kit was all NRG. All a very long time ago

Stu