The extra matching unit was made to work with NRG pll pro 3. The dipole is a NRG made difference with a balun the swr is 1.1 at the moment so all good ,when I switch on the amp the green comes on but once the blue trimmer is adjusted the orange led flickers then pops the fuse and green led light goes out too until I change the fuse .i tried a 1amp fuse and a 5 amp fuse same results

The output matching is not a function of which driver you use, so your first statement is not correct.

I'm not sure how much current this PA is supposed to draw but one of the pictures posted showed 7-9 amps so surely the fuse needs to be, let's say 10A?
It might be that the power control pot is working correctly but the fuse is too small.

Have you got a power meter to see if this PA is actually generating anything?

I don't like the look of that circuit and 25w is pretty low output for that transistor which is rated at 40w and can quite easily do in excess of 60w...

Is that the correct transistor for that circuit or was it changed from something like a PT31963?
There's also a lot of set value caps which may need changing (or to a trimmer) or at least the size of some coils will need adjusting.

teckniqs wrote:I don't like the look of that circuit and 25w is pretty low output for that transistor which is rated at 40w and can quite easily do in excess of 60w...

Is that the correct transistor for that circuit or was it changed from something like a PT31963?

A friend of mine bought the 30W amp from that a****f and it's exactly the same as this with that blue trimmer being used as an attenuator. A stupid design in my eyes as well.

Even with the trimmer set not to attenuate, the most he's had out of his amp is 28W with a 1W drive.

As far as I remember, these things draw around 5A at full tilt, but it's a long time since I've seen one being used.

The 2N6084 is used in these as standard - a real old inefficient transistor from the 80s or 90s era as used in Taxi rigs, etc.

Analyser I was only going with what I was told who had this unit that it was to match the NRG pll .i haven't got an idea why it has an extra matching unit on it .tekniqs your most probably right .but with a proper schematic for this unit would be a good sign to say that's how it was .ill send a picture of the capacitors if that helps tekniqs .frommwhat I was told it's the same output chip from back when Veronica had it . Mixin I'm no sure about a****f there designs are like a burst bag of potatoes !!!!

Tekniqs here is the capacitors used in the 25 watt amp all marked .
https://www.dropbox.com/s/cx3ibh9tqh3w1 ... 9.jpg?dl=0

Here's the output of the 2n6084 chip data

https://www.dropbox.com/s/z1tzs6195xk5j ... 7.jpg?dl=0
Data off the 2n6084 chip

Fmtx wrote:Analyser I was only going with what I was told who had this unit that it was to match the NRG pll .i haven't got an idea why it has an extra matching unit on it .tekniqs your most probably right .but with a proper schematic for this unit would be a good sign to say that's how it was .ill send a picture of the capacitors if that helps tekniqs .frommwhat I was told it's the same output chip from back when Veronica had it . Mixin I'm no sure about a****f there designs are like a burst bag of potatoes !!!!

This is 100% the same as the a****f 30W Amplifier from about 8 or 9 years ago when they were housed in plain Aluminium enclosures, but let's not forget - the tosser from a****f copied everything from Veronica before taking Steven Moss to court and then taking the Veronica trademark.

The stuff a****f makes now is even worse than this, severely overpriced, and looks completely different.

That amp looks dodgy, I'm assuming it's not an original Veronica (i.e. Moss) design, which is why I've kept my trap shut until now. I suspect you won't find a published circuit for it as looking at the matching, it looks like a design possibly for another PA transistor which has been bodged around with until it "works".

A few questions.

1. Are you applying drive to the amp when you're adjusting the blue trimmer which pops the fuse.
2. The solder work around the input to the first stage is bad, you need to check for shorts, I can see some suspect blobs on your picture.
3. When you say "the small coil on top right has broken off" which one do you mean? I am assuming you're talking about the choke (about 15 turns on a resistor with a ferrite bead on one lead) from what should be the collector to the +ve supply. I'm further assuming that there's a link under the board to get the Vcc across to the driver stage.

The reasons I'm asking all of the above is I'm wondering if you're causing the PA to take off when you're adjusting the blue trimmer.

All other comments as per what Analyser and Teckniqs said.

Yes I'm applying a 1watt NRG pll pro 3 into it .ive just managed to fix the pll as the lad who had it had components missing and burnt out so replaced all that is now pushing power .so 1watt into this pops the amp fuse when blue trimmer amp is adjusted. There is no shorts .solder was a quick fix nothing special still conducts perfectly.yes the coil the choke on the top.
right no the lad who had it had components broken off and it's all been replaced well I think but dunno for completetion until a proper schematic is still around .however the schematic that is above seems to be half right ,but the rest remains in question marks cause half the components don't match that schematic .i don't see any link underneath apart from a transistor which is underneath upside down s you can see the legs on the top right with the gold part.

they blobs that your seeing was already there apparently the lad who had it sent it to NRG to repair 5 years ago ? I asked him why not Veronica he said they don't want to touch there old designs and offered him to buy a new one .so there on he asked NRG if he would fix a Veronica amp for him .he said since your a good customer ill repair it .that probably why it says tested on the amp .and he tried recently to get it fixed from brg but he's been told there no longer is a NRG to repair that unit .

Got to remember this unit has been repaired loads probably so I wouldn't expect it to be soldered like it's been done on a machine spot on like .ive seen worse than this .

I'll have to dig out some old photos but the matching on the back end of that amp really looks like tbe 50v, 100w PA Steve Moss did. I had an Aaaaaaaaaref rig on the bench a couple of years ago and I'm sure it had C-L matching after the final, rather than L-C, which is the same as your amp. Having said that the transistor hole would be different but it would be odd for the output match to be the same.

Now you mention it I've seen something very similar he did using a BLW86 but that's 28v, as you know.
....Will see if I can get a picture.

Analyser wrote:I'll have to dig out some old photos but the matching on the back end of that amp really looks like tbe 50v, 100w PA Steve Moss did. I had an Aaaaaaaaaref rig on the bench a couple of years ago and I'm sure it had C-L matching after the final, rather than L-C, which is the same as your amp. Having said that the transistor hole would be different but it would be odd for the output match to be the same.

I was wrong, just found the picture and although the matching scheme is similar the values are different so it's not the same PA.

Ok guys found this on my travels .see this 20 watt blx69 schematic that is posted on here is that for this circuit ????
This is a 20 watt believe it or not .
https://www.dropbox.com/s/8nwchsgjes1vd ... 9.png?dl=0

The output filter won't do anything useful!

The output filter is not precise your correct Albert .

Ok folks it is now working .was a technical fault with a missing few capacitors which was resolved thanks guys
https://www.dropbox.com/s/ovavfrs67ushe ... 8.jpg?dl=0