MiniTiouner LF and HF interference

Discussion about the MiniTiouner board and the MiniTiouner Digital ATV Receive Software. See also http://www.vivadatv.org/index.php
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Basil
Posts: 82
Joined: Tue Sep 10, 2013 7:28 pm

MiniTiouner LF and HF interference

Post by Basil » Tue Oct 12, 2021 10:35 am

I am a bit of an LF fan and use 136kHz a lot. Since building a MiniTiouner (that works very well) I am seeing hundreds of spikes on LF and top band. Powering down the MiniTiouner, or disconnecting the coax to the dish, at the receiver end, kills it. I am suspecting the buck regulator board from Ebay, but thought I'd ask if anyone here has seen a similar issue and if you attempted a fix? Thanks.


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G3GJA
Posts: 166
Joined: Sun Nov 20, 2011 3:44 pm

Re: MiniTiouner LF and HF interference

Post by G3GJA » Tue Oct 12, 2021 10:47 am

That will be down to the DC switched mode regulator proving the 4 volts to the regulator ICs.

The cure is to turn the Minitioune off!

Clive

g0mjw
Posts: 1709
Joined: Sat Sep 20, 2014 9:15 am

Re: MiniTiouner LF and HF interference

Post by g0mjw » Tue Oct 12, 2021 11:59 am

I don't see this myself but the little regulators can be noisy and they are not all the same quality. Usually these signals are transmitted through the power supply but perhaps not in your case. If disconnecting the coax fixes it, this implies there is noise being transmitted on the coax and picked up by your LF antenna, Therefore you ought to be able to reduce it with a suitable ferrite choke over the cable.

It might not be the regulator, it could be coming from the USB connection, but you don't have to use the specified one, you could use a 3A linear regulator instead but be aware it will dissipate a lot of power from a 13.8V supply. Alternatively add some filtering to the input side, e.g. a choke and capacitor. Don't ask me for the values, I don't know.

Mike

Basil
Posts: 82
Joined: Tue Sep 10, 2013 7:28 pm

Re: MiniTiouner LF and HF interference

Post by Basil » Tue Oct 12, 2021 12:32 pm

OK gents, thanks for the ideas, I THINK unplugging the USB cable made no difference, but I will get hands on again tonight.

Basil
Posts: 82
Joined: Tue Sep 10, 2013 7:28 pm

Re: MiniTiouner LF and HF interference

Post by Basil » Thu Oct 14, 2021 7:35 am

I think the eBay buck converter board is faulty, since turning it off (it ran 24 hours, seven days a week like the PC before I started investigating the noise) it has started shutting itself down. There's no power LED showing when it shuts down, but power is still getting to the power input.

As the LED is powered directly from the buck converter I have to assume the converter is stopping. And probably noisy when it is working. I should have socketed it...

G8KOE
Posts: 54
Joined: Fri Aug 09, 2019 8:14 am

Re: MiniTiouner LF and HF interference

Post by G8KOE » Fri Oct 15, 2021 8:22 am

I always fit a DC filter after a buck converter.
A choke followed by a 100uF.
Choke not critical I used common ones found on eBay
Put a scope on DC O/P from buck converter and see the difference.

73's
Martin
G8KOE
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