I have the choice between two NRG Pro 3's as a driver for a 100w amp, but have noticed that one of the boards has a resister soldered beneath the output transistor, and the other hasn't.

Does anyone know what the purpose of this resistor is?

Why would one board have one and not the other?

Thanks

I'd use the one on the left as it has a heat sink on both transistors.

....that's not a resistor it's just a wire link that's why it just has one single black stripe in the middle and not the usual selection of colour coded bands.
There's no need for it to be there and it serves no purpose apart from trying to disguise the longer wire link underneath.

teckniqs wrote: ↑Wed Feb 10, 2021 5:00 pm I'd use the one on the left as it has a heat sink on both transistors.

....that's not a resistor it's just a wire link that's why it just has one single black stripe in the middle and not the usual selection of colour coded bands.
There's no need for it to be there and it serves no purpose apart from trying to disguise the longer wire link underneath.

Thanks for your insight.

With the two metallic squares on the board, it seems as though something should be soldered there.

I used to have an original NRG Pro 3 years ago, but can't remember how the board base looked.

So you think this resistor was just placed there for aesthetics, and the bridging of these squares has no effect on performance?

The one on the left, but for slightly different reason, it has the original size LED’s . Mine has the larger ones, even though it’s blue pcb
Personally I don’t care that their is a heat sink on both transistors , that smaller one hardly get warm anyway, that’s why the second can work happily without. Also I notice some of the coils have wax in them on the one on then,eft, so it keeps pesky hands out of what has already been made to work best. I would use the one you don’t mind loosing Are you selling the spare?

Barry06 wrote: ↑Wed Feb 10, 2021 5:41 pm
Thanks for your insight.

With the two metallic squares on the board, it seems as though something should be soldered there.

I used to have an original NRG Pro 3 years ago, but can't remember how the board base looked.

So you think this resistor was just placed there for aesthetics, and the bridging of these squares has no effect on performance?

Yes it's definitely not a resistor it's just a wire link for when a direct wire link short is required instead of a resistor and it's not doing anything on your board.

LeeCavanagh wrote: ↑Wed Feb 10, 2021 5:48 pm Personally I don’t care that their is a heat sink on both transistors , that smaller one hardly get warm anyway, that’s why the second can work happily without.

In most cases you're probably right and you'd get away with it, but say it was inside a box with other high powered gear jacked down a tight hole with poor ventilation on a hot Summers day!
...So yeah, always best to clip one on there even if it's not barely even getting warm at all on the bench (it's better to be safe than sorry and they only cost pence).

The wire link is there to bridge the ground planes, and will result in a very slight power increase. If the whole board was re done on double sided FR4 you’d get just over 5 watts out at the lower end of the band and closer to 6 watts out at the upper end.

nrgkits.nz wrote: ↑Thu Feb 11, 2021 11:17 am The wire link is there to bridge the ground planes, and will result in a very slight power increase. If the whole board was re done on double sided FR4 you’d get just over 5 watts out at the lower end of the band and closer to 6 watts out at the upper end.

Does this bridge affect the power output when the transmitter is set to 1 watt?

I’m using this to drive a 100watt amp that requires a 1watt input. I’m concerned that anything higher could damage the amp.

Barry06 wrote:

nrgkits.nz wrote: ↑Thu Feb 11, 2021 11:17 am The wire link is there to bridge the ground planes, and will result in a very slight power increase. If the whole board was re done on double sided FR4 you’d get just over 5 watts out at the lower end of the band and closer to 6 watts out at the upper end.

Does this bridge affect the power output when the transmitter is set to 1 watt?

I’m using this to drive a 100watt amp that requires a 1watt input. I’m concerned that anything higher could damage the amp.

Remove the jumper then you will have 1 watt put jumper back in gives you more power so remove jumper to decrease the Watts to 1 watt.

Sent from my AMN-LX9 using Tapatalk

The wire link will give (roughly) a 10% power increase at the bottom of the band, and about 15% more at the top. The PA stages in that board were designed for a slight slope in power output, with a bit more at the top end of the band than at the bottom. This was to compensate for the gain slope of the BLW60 amplifier that was most commonly used with this board. The BLW60 would give exactly 50 Watts on any frequency from 87.6 to 107.9MHz when driven from this board (with the wire link) at ~15V supply. We used to adjust the PSU voltage with the PLL set to 98.4MHz (the geometric centre of the band) to get exactly 50 Watts into 50Ω, and then you'd get pretty much 50 Watts right across the band.

Albert
50 ? Surely you mean 5 ?

Or do you mean into an amp?

LeeCavanagh wrote: ↑Fri Feb 12, 2021 1:07 pm Or do you mean into an amp?

He means the BLW60 final output stage. (50w)

Yeah ok, thought so after i had sent my initial message, Thanks, that makes sense, i guess the slope on the BLW60 was pretty bad then, never used it myself.

The beauty of the BLW60 was that it cost about £1.50 in quantity, and would easily do 50 Watts!

Hi Is possible get PCB scan layout gerber ?

There never were any Gerbers for these boards - they were designed using "EasyPC" made by Number One Systems. This was an ancient DOS PC design programme that Stephen used. I got a copy and did some of the design work myself - adding OLPD to the Pro III and a few other changes. I also used that same programme for the Pro III and Pro IV stereo coders and for the stereo limiter.

Albert H wrote: ↑Wed Dec 04, 2024 1:58 am There never were any Gerbers for these boards - they were designed using "EasyPC" made by Number One Systems. This was an ancient DOS PC design programme that Stephen used. I got a copy and did some of the design work myself - adding OLPD to the Pro III and a few other changes. I also used that same programme for the Pro III and Pro IV stereo coders and for the stereo limiter.

im find this one..

Looks like someone copied the old EasyPC files into Sprint!

do you have the compressor limiter ?