DATV/SSB PA For Pluto or Lime SDR

Items for sale here please
Forum rules
This forum is run by the BATC (British Amateur Television Club), it is service made freely available to all interested parties, please do not abuse this privilege.

Adverts will be archived when the seller indicates that the item is sold or after one year. If you wish to keep advertising after one year, please re-post.

Thank you
G1BVI
Posts: 234
Joined: Wed Aug 02, 2017 7:32 am

Re: DATV/SSB PA For Pluto or Lime SDR

Post by G1BVI » Mon May 02, 2022 5:01 pm

Thanks Mike
Had not spotted those looks just what the doctor ordered

73

Nick
G1BVI

radiogareth
Posts: 933
Joined: Wed Jan 06, 2016 9:46 am

Re: DATV/SSB PA For Pluto or Lime SDR

Post by radiogareth » Mon May 02, 2022 5:54 pm

Its nice to have no fan noise, they still need good ventilation though, I was told stuff like that had a fan assisted back-plane sort of arrangement rather than individual fans.
To get 28V you need to stack TWO of those '12V' PSU, ie, bottom one just tweaked as per mod to 14V, top one needs its 0 Volts isolating from the case, then join bottom +14 to top '0', the next +14 gives you the 28 WRT 0. The Electric RC flight people do it lots, in varying degrees of common sense.
Sooo much easier to buy one that's already at 28V....
Gareth

g0mjw
Posts: 1897
Joined: Sat Sep 20, 2014 9:15 am

Re: DATV/SSB PA For Pluto or Lime SDR

Post by g0mjw » Mon May 02, 2022 6:07 pm

Good point Gareth, they don't need much ventilation but they definitely need some. One of those USB fans for example or a stack of ex-broadcast DVB-T amplifier power supply fans along one side. You can get 28V too, rather than 27.2v. I posted a mod but they come in various designs so best understand the circuit before attempting it. it involves modifying the feedback which is via an optical isolator and don't mess with things elsewhere or it might become unstable and that's never a good thing with a power supply.

Mike

G1BVI
Posts: 234
Joined: Wed Aug 02, 2017 7:32 am

Re: DATV/SSB PA For Pluto or Lime SDR

Post by G1BVI » Mon May 02, 2022 6:22 pm

I made the mistake of NOT isolating the Ov when I tried to combine them before and can testify to it causing fireworks !!!
73
Nick

User avatar
M5TXJ
Posts: 269
Joined: Wed Jul 05, 2017 8:34 pm

Re: DATV/SSB PA For Pluto or Lime SDR

Post by M5TXJ » Mon May 02, 2022 8:08 pm

I've built a 32V PSU for my QO-100 amp using 3 of the HP server units modified to give 10.7v and the output isolating from ground on two of them. It works really well and the server units only cost £3 each. I had some shouldered spacers 3D printed to support the board where the grounded pillar had been, that and an M3 nylon bolt did the job perfectly.

73 Dave.
...are you sure I can't use a pair of 813's?... :shock:

User avatar
M5TXJ
Posts: 269
Joined: Wed Jul 05, 2017 8:34 pm

Re: DATV/SSB PA For Pluto or Lime SDR

Post by M5TXJ » Mon May 02, 2022 8:18 pm

Oh as an aside, if you replace the M3 screws securing the PCB with longer ones you produce some handy mounting points as there isn't anything use friendly as they arrive. You can either fit the longer screw ends through a chassis and secure with nuts or use hex spacers and use screws into those.

73 Dave
...are you sure I can't use a pair of 813's?... :shock:

G1BVI
Posts: 234
Joined: Wed Aug 02, 2017 7:32 am

Re: DATV/SSB PA For Pluto or Lime SDR

Post by G1BVI » Fri May 13, 2022 6:57 pm

I secured the Nokia Amp to a heat sink 430 x 150
My PD4 is fitted with a lime mini which is fed int AMSAT UK driver amp to give 0dm out.
The Nokia amp is connected to a 28v 25A supply.

I measured the output power at just over 60w.
Verry impressive but it will need a fan to take the heat away,



See image (30db attenuator on output)
60w.jpg
60w.jpg (1.26 MiB) Viewed 388 times

Post Reply

Return to “For Sale”