BATC Forum

Hi all

Has anyone had either a Stealth 3437 series PA or one of the ex-Ionica PAs up and running with DATV on 9cm?

are they linear enough to be usable? If so, what sort of power level are they capable of before the shoulders present a problem?

John
G8PEF

I have the Stealth unit. It will needs fans! Wondering the same as I can't specifically 'measure' power on 3.4GHz - my test gear runs out of puff at 2.5GHz. I can look at the transmitted waveform VIA the LNB which may be adequate if I can ensure I'm not saturating it. I can drive the amp with either a Pluto or a Lime SDR so I would be interested too, if nothing else, in known safe drive levels. The Stealth amp has a FWD and REV VSWR output and according to the data sheet apparently gives approx 2.5V out at +37dBm = 5 watts. Max O/P is stated as 20 Watts 43dBm but my duplexer is 10 watts max. 40dBm.

Gareth, G4XAT

I did some basic testing a year ago, and my similar Stealth unit gave a very clean 10W of DATV on 3.4 GHz. I'll be pulling it out again in readiness for the contest soon, so will check.

I was cerainly able to drive it directly from a LimeSDR, although there were some minor phase noise issues from the Lime at that frequency: https://discourse.myriadrf.org/t/limesd ... 4-ghz/4095

Dave

Thanks, chaps.
Gareth - yes, they definitely need fans! The original equipment that they we're used in had 3 X 100mm fans blowing across a pair of amps, plus a 50mm fan directly mounted on their PSU (a 12V/21A continuous rated SMPS).
I can fairly easily measure the power output of these (and the Ionica ones), but I've no idea how much you can squeeze out of them whilst still remaining linear enough for DATV. From what Dave says, 10W is certainly do-able...
They're supposed to be specced at 20W (nominal), but I believe that they aren't 'set' to any specific level - and in the wild the output can vary between 20 and 30W-ish, for the same drive level. They only require a fraction of a milliwatt drive anyway, so driving the, from a Pluto or Lime should be a doddle (unless someone has removed/blown up the first stage of the amp, of course ).


Dave - did you explore what the maximum output was before the shoulders became a problem?

Anyone looked into the Ionica '30W' lumps?

John, G8PEF

G8GKQ wrote: ↑

Thu May 23, 2019 7:45 pm

I was cerainly able to drive it directly from a LimeSDR, although there were some minor phase noise issues from the Lime at that frequency: https://discourse.myriadrf.org/t/limesd ... 4-ghz/4095

Dave - sorry, I meant to add to the above post, the following question for you:

Re: the phase <s>mouse</s> noise issue with the Lime - if I understand your post to the MyriadRF forum correctly, the issue you had was with the Lime Mini? Do you know if the (full-size) LimeSDR suffers from similar problems?

John G8PEF

Phase mouse? Auto-correct error I assume. It is the same chipset so probably. Might do better with an external reference which both Limes allow. I suggest you check it first.

Mike

Hi John

The phase noise issue was specific to my own hardware Version 1.1 LimeSDR Mini, and improved once the board had reached operating temperature (which was presumably the temperature that it was factory-trimmed at). The problem was not visible at all at 2.4 GHz, so unlikely to be an LO issue.

I tried to reproduce it with BATC Shop stock V1.2 LimeSDR Minis and they were all OK, so it seems unlikely that it will affect a LimeSDR USB unless you are unlucky.

Dave

g0mjw wrote: ↑

Fri May 24, 2019 7:15 am

Phase mouse? Auto-correct error I assume. It is the same chipset so probably. Might do better with an external reference which both Limes allow. I suggest you check it first.

Mike

Haha, that's what you get for trying to post on the forum with an ancient (small screen) phone, Mike.

Is the full-size Lime the same chipset? I thought the Lime Mini had something different in it (resulting in the more restricted frequency range), but now you've got me thinking, and I'll have to go and check, lol

G8GKQ wrote: ↑

Fri May 24, 2019 8:51 am

Hi John

The phase noise issue was specific to my own hardware Version 1.1 LimeSDR Mini, and improved once the board had reached operating temperature (which was presumably the temperature that it was factory-trimmed at). The problem was not visible at all at 2.4 GHz, so unlikely to be an LO issue.

I tried to reproduce it with BATC Shop stock V1.2 LimeSDR Minis and they were all OK, so it seems unlikely that it will affect a LimeSDR USB unless you are unlucky.

Dave

Thanks, Dave. When I get my house move sorted out I'll have a play with both and see what the differences are.