Spectrian 30 watt snow flake mod ?

[G4WIM]

Hi Guys,

some time ago I stumbled across a 'snow flake' mod for the pyrojoe 30 watt Spectrian to lift its power from 25 watts to 30 watts when used for DATV uplink.

Ok, going from 25 to 30 W probably won't make any noticeable difference - but try as I might I can't find this information.

Does anyone have a link ?

73 Tim

[g4eml]

I don’t have a link but the point on the amp that responds to snowflaking is on the output of the final FET, where the line takes a 90 degree turn before running down the end of the board. I found a fairly large snowflake (4mm square?) attached to the 45 degree section worked for me. It actually slightly overlaps the adjacent ground plane so I insulated underneath it with kapton tape.

[G4WIM]

Thanks, once I have the complete unit built up and working I'll check the power as standard then with the snow flake - luckily I have some kapton tape.

Regards Tim

[g4eml]

Mine was 21W before and 30W after which is a worthwhile gain for DATV.
I optimised the tuning at reduced power, about 10W output.

[g8gtz]

Suggest you take a look at page 15 in the new CQ-TV 263...

73
Noel - G8GTZ

[g4eml]

That article is for the 75W amp Noel. The 30W one is a different beast.

[G4IUG]

[UKMicrowaves] Spectrian 30W amp problem.
Taken from https://groups.io/g/UKMicrowaves/topics ,
the image above is re-hosted by me The text was :
______________________________________________

Hello Colin and other readers.

I feel that I can't assist your problem any more than the help you've
already received. But I wanted to add that I do have one of these
amplifiers working perfectly well at 2403 MHz, the centre of amateur
activity here in VK.

However, I did go through the whole amplifier chain trying to find
locations for solderable tabs ("snow flaking"), hoping to make it work
better at this further-out-of-band frequency. The interesting thing is
that I did find one sensitive/responsive point and it was between the
final device and the output port, where the microstrip track takes a
left hand turn - see attached '385s image. At 2403 MHz, 10 mW input
delivered 31 Watts output following this small addition.

It was also interesting that there seems to be a layer of some plastic
material everywhere which has to be melted away before the solder will
'take' - it makes the resulting soldered joint less than good looking!

Only for interest's sake, I'm also attaching a general image of the
whole amplifier.

I wish you well with rising to your challenge!

--Doug Friend, VK4OE.

[G4WIM]

Thank guys, just what I was looking for.

Hope yo have my PA up and running under test in a day or so, then I have to make the dual feed and align etc.

All in all it's coming together....

73 Tim

[tonyaxn]

Please let us all know how you get on Tim.

I have just purchased one of these from the seller on ebay and have measured 20W out for 10mW in on 2407.750 Mhz.

The photo attached of the PA shows that a snowflake was added at some time either on manufacture or later.

So to optimise do I move it or add another ?

73 Tony G4AXN

[g4eml]

When you try to add another the original one will probably come off anyway. The exact size and location will be different for each amplifier so it is a trial and error technique.