Hello Necks,

Acquired these boards off someone and I beleive these orginally came from NRGkitz?

Didn't find too much on them at first but believe I've found the circuit diagram.
http://www.gareth.net.nz/nrgworkshop/15 ... ircuit.htm

Here is a board if anyone can confirm the circuit diagram I would be grateful!

150w PA PCB

Looks like the old Veronica board which used the MRF150 from around 20+ years ago.

Yep - that's Steven's 150 Watt board. He used the MRF150 in the early ones, and the BLF177 later on. There was a separate board that took an additional lowpass filter.

No albert this was the one with the 5 pole LPF and the board
i can look if i can find a picture
this board was also used for the 200W version with the "BLW96"

Thanks for the information so far.

I found pic also...... Looks like a BLF177?

The schematic you have is the Phillips test circuit which does work!

However i doubt Stephen ever published any PA schematics from personal experience?

I was sent a clearer picture which may help? Only a guide ofcourse!

The PCB itself is pretty generic and could be useful for a number of PA configurations!

wow sinus
i was a fan for thoses trimer vishay and philips from the beginnig of the vco ...but i still confused how do they handle such power , even if they are in parallel .

sinus trouble wrote: ↑Fri Jul 09, 2021 11:31 pm The schematic you have is the Phillips test circuit which does work!

However i doubt Stephen ever published any PA schematics from personal experience?

I was sent a clearer picture which may help? Only a guide ofcourse!

The PCB itself is pretty generic and could be useful for a number of PA configurations!

IMG-20170430-WA0001.jpg

Thanks Sinus, That alot more helpful than the image I have!

I also acquired a CD with NRG stuff on it but no component values with the 150w PA just layout, In the files it even has a "combined" driver with amplifier (10w/40w) circuit. That I don't remember seeing it being published before.

I have 10 x boards and a quite a few BLF177's, so may build them up.

Radium wrote. " i was a fan for thoses trimer vishay and philips from the beginnig of the vco ...but i still confused how do they handle such power , even if they are in parallel . "

There are 2 different types of Philips/Vishay trimmer capacitors:
At input side, the only trimmer seems to be a 808 Series - Polyethylene film capacitor, operating temperature is -40ºC to +70ºC.

At the output side you have three 809 Series PTFE Film trimmers, operating temperature is -40ºC to +125ºC. That's the reason why they handle high power.

Gigahertz wrote: ↑Sat Jul 10, 2021 10:37 am In the files it even has a "combined" driver with amplifier (10w/40w) circuit. That I don't remember seeing it being published before.

Do you mean one of these??

Gigahertz wrote: ↑Sat Jul 10, 2021 10:37 am I have 10 x boards and a quite a few BLF177's, so may build them up.

The BLF177 is a crackin device, Quite sought after now and pricey!

I have one running in one of my rigs, Which has taken some abuse!

You could probably make an educated guess on what the components are? As Stephen mentioned "The Phillips test circuit is usable with a bit more capacitance in the output stage"

You could also upgrade the mica power caps for ATC types?

Either way? You will obviously need to experiment and test the spectrum.

The clear Philips "blue spot" trimmers are (normally) OK up to around 90 Watts. I've seen them melt to a puddle of plastic at higher power! The Pye Europa used them in the "high power" (AM - 20 Watts carrier, 80 Watts peak) variant of their high band (Band III) PA.

I used to re-coil those boards (with the Thomson SD1019 output transistor) for Band II use, take the modulator out of the rig altogether (and use it in little SW AM rigs), and replace the crystal-controlled exciter with a PLL job. The Band III receiver got a new crystal, and a wideband IF strip, carrier-detection and tone "whistle-on", and I'd reduce the voltage to the PA stage a bit. They made a really neat 80 Watt rig, with a built-in link receiver in a case that didn't look out of place in amongst other Pye and Burndept gear screwed to the wall on the "Facilities" Sites that I used to use.

The "whistle-on" circuit was a simple NE567 tone decoder IC tuned to 22 kHz, and a bit of logic operating a relay. The logic ANDed the output of a bistable ("set" when the 22kHz control tone was heard) with the carrier detect. When both were true, the relay pulled in after a few seconds, enabling the output rig. As long as the link was present, the relay would hold in, and at the end of broadcast, the link carrier was switched off at the studio end, and the relay would drop out, the bistable would reset and the whole thing went back to standby, ready for the next broadcast. At the studio end, there was a "Transmitter Enable" push button on the mixer, so the procedure was for the first DJ to switch the link on, and wait for the "Locked" and "RF Out" LEDs to light green on the link rig, and then push the "TX Enable" button until he heard the rig start up. At the end of the broadcast, the last DJ just had to switch the whole studio off for the main rig to shut down!

I made a whole load of those "Pye" rigs after I bought about 50 of the ex-MOD AM rigs at an amateur rally at Woburn. I think that I might still have one somewhere in the warehouse.....

thanks ...

As mentioned, The trimmers in the output stage are tefflon based which has a higher melting point than PVC or materials alike!

Whist the trimmers can withstand the rated power? They are also susceptible to mechanical stress which can cause premature failure!

Power levels up to 150w are generally acceptable? Problems arise when they are subject to fault conditions or poor SWR! All that energy dissipated in the output stage will inevitably cause failure within the chain.

thank you sinus

sinus trouble wrote: ↑Sat Jul 10, 2021 11:24 pm

Gigahertz wrote: ↑Sat Jul 10, 2021 10:37 am In the files it even has a "combined" driver with amplifier (10w/40w) circuit. That I don't remember seeing it being published before.

Do you mean one of these??

20210710_225518.jpg

Yep thats the circuit

Very nice!

May I suggest you use the Elenos circuit for the BLF177 rather than the Phillips test circuit? It's broadband so you don't need to worry about trimmers failing.

The only thing it doesn't include is a low pass filter but it's easy to add one on.

sinus trouble wrote: ↑Sat Jul 10, 2021 11:24 pm

Gigahertz wrote: ↑Sat Jul 10, 2021 10:37 am In the files it even has a "combined" driver with amplifier (10w/40w) circuit. That I don't remember seeing it being published before.

Do you mean one of these??

20210710_225518.jpg

I've got one of these thrown in a box at my storage unit somewhere.

Bton-FM
https://www.bing.com/images/search?view ... de=overlay

http://mkmbroadcasting.blogspot.com/201 ... ilter.html