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Drive will be a Pluto via DVBExpress. Rx will be another Pluto running on DVBS2GUI. So far so good.
But what sort of signal/voltage might have been used on the 'gain adjust' input? 0-5 volts, or perhaps a PWM (unlikely??). Don't want to cause harm to what could be a great piece of kit, but not surprisingly, Google did not find any user manual for the product....
TIA - all suggestions welcome (other than 'sell it to me'!!)
Drive is about 0dBm.
Just got 5.665 working across the shack (DVBSGUI not yet extended for the Pluto up to 6GHz) but SDRAngel does now do DVBS2 and that is working great at 333kS with audio too.
I assumed the circulator might be frequency dependant but its presence (I assume) helps protect the final device?
Is it safe on 13.8V or a definetely 12V only device?
Pluto driving it should be fine but you need to loose a bit of power if driving with an FPV unit as it only needs 1 milliwatts. 13volts is fine, although they do get hot as they draw ~8 amps and mine runs ~10 watts. Put a pot between 12v and gnd and take the center to the gain control - start at the gnd end and wind it up for max output - not smoke!
Hope to work you over the weekend - there should be 4 of us on 5.7Ghz DATV.
Note DATV is around 5760 MHz which is center of the NB section and NOT 5665 as most of us are using NB transverters. I'll probably be on 5762.5MHz which is an IF of 146.5 MHz.
I've some -10dB pads (for using a Pluto with SATSAGEN) that will help with drive curtailment and of course ExpressDVB has a drive power slider.
I have a couple of PAs similar to the one shown and have recently run some tests. I say similar because the type number and frequency range on the label are different. I also have the original power supplies that came with the PAs and on my units the original gain control is achieved using a 100kOhm variable resistance to chassis, with maximum gain = 100kOhms, minimum gain = zero Ohms.
In the linear(ish) region with 10W output the gain is about 53dB, with the gain control giving a 12dB range. The maximum output power was about 16W. DC input 7.9A at 12V. All tests at 5762.5MHz.
As far as I am aware, the PA has not been modified, with the insides looking quite clean.
Irrespective of the label, the PA seems happy at 5762.5MHz. Regarding the o/p circulator, I would leave it there as it's protecting the PA and the improvement in o/p power in removing it may only be a fraction of a dB.
You can see a few photos below.
Edit: Better photo of test set-up uploaded
- 5.7GHz PA Test.jpg (1.5 MiB) Viewed 475 times
- 5.7GHz PA Lid Off.jpg (1.87 MiB) Viewed 514 times
- 5.7GHz PA OP Section.jpg (1.88 MiB) Viewed 514 times
- 5.7GHz PA Driver Section.jpg (1.63 MiB) Viewed 514 times
Needed the second heatsink, it was getting just a bit too hot without it.
Now to arrange tripod fitments etc, or maybe remove my FM-Drone gear from the pair of flat-plates I have already on a mount. That would simplify RX/TX switching.
Doesn't seem to need much drive from the pluto, but no real way of measuring output power at these frequencies ATM. Gareth