Impressive heatsink - where do I get one?
(and how is it held on?)
My impression with these double sided pads is that they don’t conduct heat too well.
If you can manage it a 8 cm fan just blowing at the RPi is probably better heat removal and quieter than one of the small fans with dubious double sided tape.
The heatsink above looks neater though and with all the cases people get that seems important to most people 
That’s the good news. The bad is that when they get too hot, the heatsink falls off.
A heatsink that size shouldn’t get ‘too hot’, but if the heat pad doesn’t conduct, the heatsink can’t do much.
Yeah, I was concerned that it may fall off when it gets hot so it’s going to be held in place by alternate methods as well - probably a combination of cable ties and paracord or possibly enamel coated wire wrapped in heatshrink. Or even just some string. I don’t want it dropping off when it’s 35ft up in the air!
I didn’t think to check the temperatures before putting the HSF on the Pi but there’s a 10°C drop in temperature when I plug the fan into the 5v rail and about 8°C drop if I use the 3.3v rail.
Just an idle thought, but a 12V fan on the 5V rail is probably better than a 5V fan on the 3.3V rail just because the 5V is straight to the supply while the 3.3V is on the ‘inside’ of the onboard regulator.
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I’ll be running it on the 5v rail for maximum effect. It doesn’t matter if it gets a bit noisy, it’s outside and up in the air!
Hi Keith, sorry a bit late to the party… browsing for ideas on various ways to mount kit externally and ended up here. I like this approach of taking power directly to the kit (I’ve seen a few reports of POE acting unreliably). Is it connected via wifi or did you run a network cable later on?
What voltage and power are you sending up to the box to convert to USB voltages with that little PSU board?
Looking at your live map that’s a really impressive amount of coverage, really nice.
I noticed later on you picked up another Airspy and a bias-tee. Can you explain or perhaps sketch out connection-wise how this approach would be used to connect and power everything (the RPi, the Uputronics if you have one in this new setup, etc) versus the above method which has dedicated power to the box feeding the RPi and Uputronics directly?
I have a RPi, the external FA antenna, a Uputronics SAW filter and the ProStick Plus and have been feeding for just over 2 years from a windowsill. I’m keen to move the kit outdoors onto the roof in 2020. I was looking at running 20ft of coax but that means either having the preamp far away from the antenna, or else having the preamp on the roof and powering it one way or another in a weatherproof box anyway, so your box setup is kind of looking like the tidy, logical endpoint of that approach to simplify things even more.
I welcome suggestions!
EDIT to add: I don’t have easy access to the roof so I think I’d like to keep the RPi indoors. I guess that means the ProStick Plus stays with it too (no daft USB cable runs). In that case, am I looking at the FA antenna on the roof along with the Uputronics preamp, and then powering that through bias-tee? I’ve never looked into bias-tee before so it’s a new area for me. No idea what’s needed up on the roof or downstairs with the PSU, nor anything that might be important to consider, so I would welcome any pointers from your ham experience.
EDIT EDIT (sorry, thinking of new things after I hit send!): Perhaps better is to power the Uputronics using a dedicated higher voltage cable up to the roof, and then dropping that down to USB level inside the box, similar to what it looks like you did in your box to power both devices. Disadvantage - a voltage converter and two cables (power and coax) needed. Advantage - no bias-tee or DC injection needed.
I’m assuming that running coax from the antenna into the house and THEN into the Uputronics is not ideal - from what I understand the preamp wants to be close to the antenna. At the moment indoors it’s 1m of CLF200 coax away which I feel I should be moving en-masse to the roof.
Gawd, this hobby does have a way of taking over one’s mind somewhat doesn’t it!
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Hi Chris (I’m assuming your name is Chris from your username, apologies if I’m wrong).
This particular receiver is at the Martello Tower Group site and I’ll refer to it as the MTG receiver, just to separate it from my own box at home.
The MTG feeder has two cables going up the mast, one is ethernet straight into the Pi3B+ and the other is carrying 13.8V from a very old Daiwa PS-140II PSU rated at 10A. We take the output from that and feed it into an LM2596 based dc-dc converter set to around 5.1V which then links direct into the Pi and the Uputronics LNA.
Would I recommend this again? No, I don’t think I would as I had some issues with a similar setup at home where after a few months, the output voltage from the LM2596 converter dropped and the Pi was in a permanent state of throttling. The Raspberry Pi4 needs even more power and I think it’d be too much strain on this little converter.
I don’t know if you’ve seen the full details but a few weeks ago, I rebuilt my home receiver and I’m now using a Pi4 along with the Airspy Mini and RTL-SDR LNA. I detail that build (albeit with no pictures of the inside of the box) on my blog here. I list every piece of equipment I’m using from the aerial down to the PoE injector in my radio shack.
Regarding what you’re planning, I’m very firmly of the opinion that the LNA should be as close to the aerial as is practical so if you can do it, I’d have it mounted in a small waterproofed box directly below the aerial and powered by the bias-tee injector I’ve linked to in my blog. I power the bias-tee with two wires soldered directly to the 5V GPIO pins on the Pi4.
So aerial, Uputronics LNA, coax down to the equipment, bias-tee module, dongle, then Pi. If the Pi is indoors then you could simply power it with a standard RPi PSU.
One thing to consider is that you’ll actually be running two amplifiers because the ProStick Plus has one built in. It’s not a real issue with a windowsill aerial but you may find it’s overkill with an external aerial. If you don’t want to spend £100 on an Airspy then I’d seriously consider swapping the ProStick Plus with either the standard ProStick that doesn’t have an LNA or the RTL-SDR-V3 dongle.
Other people will disagree with me and honestly, 20ft of coax isn’t a huge length so as long as you use decent cable (don’t skimp on coax, buy the best you can afford), then it’s not going to make a huge difference. However, I always like to build the best I can and after over thirty five years of being a radio amateur, I always try and eek the last few dB out of any system and don’t like introducing unnecessary loss or noise into the RF chain.
I think I’ve answered everything and I hope I haven’t complicated things further for you. Feel free to ask anything else, I’m not an expert but I’m always happy to try and help.
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Standard ProStick has the LNA minus the filter.
So it’s really not a good choice for ADS-B at this point in time with the blue one being available.
Having up to 5 m of LMR400 before the preamp isn’t an issue, even more still produces good results.
So it’s perfectly feasible to have the filtered LNA indoors.
Using a bias-T is really not an issue, the LNA has a wide range of input voltages it will accept and most coax is rather low loss in regards to DC resistance, so it’s normally a non-issue.
I’d say it’s perfectly good to use the ProStick+ with the uputronics filtered amp.
With the rtl-sdr filtered LNA which is my favorite, i’d probably not use the ProStick+ as the rtl-sdr LNA has 10 dB more gain.
But it’s also been done and works.
What is nice about the rtl-sdr v3 receiver or the NESDR SmarTee, they have a bias-t builtin and can supply the LNA with power without an external bias-t needed.
I stand corrected, thank you.
By coincidence, Tony is at the MTG site right now replacing the Uputronics LNA with an RTL-SDR-LNA.
Personally i think Rtl lna is a better 1
I totally agree. A big problem with the Uputronics LNA is the susceptibility to strong, nearby signals. 5W on 145MHz from our co-sited SSTV repeater would cause complete overload, dropping ADS-B signals down to zero within a second or so.
The RTL-SDR-LNA doesn’t suffer from this - As can immediately be seen from the graphs.
Strange, i have tested at less than 1 meter from mine with a VHF/UHF radio, and i haven’t this problem.
Tested on 145Mhz like you with 8W.
The antennas weren’t 1 m from each other were they?
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No sorry the 1meter is beetween the Radio and the Uptronics.
The radio antenna was at 5 or 8 meter from the ads-b antenna.
Which version of the Uputronics? I’ve experienced this with two now, both with the ceramic filter. In each case, the 2m aerial was within about four or five metres of the LNA.
It’s a ceramic model.