Strange problem powering MiniTiouner v2.

[G8DPH]

I have a number of LM317s! Might require a heat sink though.

[g4eml]

Changing to a linear regulator down from 12 or 18V will produce a lot of heat.
It doesn’t need to be 4V. 5V will work fine. It just produces a little more heat from the regulators but it is not excessive. I do it like the previous poster and run mine from the USB 5V supply. All it needs is a link wire from the USB module supply pin to the jumper.
The external power socket can still be used to supply power to a LNB if needed.

[G8DPH]

Good idea! Perhaps use a suitably rated diode in place of the link!

[YL3AKC]

Next level for me: add DC-DC upconverter from 5V to 12V for LNB supply. Then add resistor network and get 5V => 12V or 5V => 18V switching for LNB. Need to make some tests. Concerning about DC-DC noise. If everything will be fine, then miniouner can be supplied from 5V USB powerbank.

[g0mjw]

Be careful. You could blow up your USB port. I can't see any harm in doing that through a powered USB hub but if the power fails and the USB port is asked to supply more than 500mA without actually being asked. Might be OK, might not. Its a lot easier just to use the DC-DC converter as we have been for the last 3 years.

Mike

[g0mjw]

Next level for me: add DC-DC upconverter from 5V to 12V for LNB supply. Then add resistor network and get 5V => 12V or 5V => 18V switching for LNB. Need to make some tests. Concerning about DC-DC noise. If everything will be fine, then miniouner can be supplied from 5V USB powerbank.

A 5V powerbank, or even just a 5V USB charger. LNB - If you are going to go to the trouble of modifying the LNB for an external reference of TCXO you might as well do the resistor mods at the same time so that you have permanent H from one port and V from the other. Then you can run it off a lower voltage, say 9V. The current will be the same, no 12/18V switching needed.

[YL3AKC]

I already done voltage mod for my twin LNB with RT320M mixer.
It is similar to this LNB, but without 10 GHz BPFs.
Now from first port I have Hpol, from second port I have Vpol.
It's done my changing divider resistors and connecting them to +5V rail inside LNB.
Maybe in future I will add capacitors to get 22 kHz signal from ports.
Then I summed both signals together thru cable TV splitter with power pass. Cable tv splitter is OK there, because of 740 MHz IF frequency.
Now I have full spectrum in one cable. Polarisation (skew) is adjusted quite well and no problems to receive NB+WB signals.
In shack I have 12V (can change to other voltage) power inserter and that it. I can split signals and feed them to minitiouner, LimeSDR and RTL-SDR etc. As bonus, I can retune LimeSDR to NB or WB simply by changing frequency, no cable reconnection involved.

External reference will be implemented later. Now I am busy with "polish amp" (WiMAX 2x50W) hacking for BIAS settings.

Biggest and annoying problem is that Minitiouner won't work on RPi now.

[Keith G8VMP]

Just noticed this thread after having posted my power problems earlier!

My buck converter is broken too - it didn't like the load applied and blew the zener.

So I ordered another off ebay but have noticed its the same supplier you had problems with....doh!

Keith

[G8DPH]

2 of the modules from the first supplier take about 30mA with no load. Looked at output on scope - they were oscillating!

Got a new module from a different supplier. No measurable current taken from supply off load (PSU only has 3 digit current resolution)

Connected in circuit (minus tuner and USB module) It worked fine , the 3 regulators giving the correct voltages.

[Keith G8VMP]

Ashley, Could you let us know who the seller of the good one was?
I think I'll be buying more yet!

Thanks
keith