Bias-T powered filter and an Active Antenna on Port B

Useful information regarding antennas for SDR products.
Paul
Posts: 209
Joined: Fri Feb 17, 2017 9:52 am

Bias-T powered filter and an Active Antenna on Port B

Postby Paul » Fri Feb 02, 2018 4:42 pm

Does anyone see a problem with running an AM filter using the Bias-T on Port B of an RSP-2, which is connected to an active (externally powered) antenna?
To anyone with electrical/electronic nous (which obviously excludes me) this will most likely seem a stupid question, but I would appreciate an informed opinion.

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g1hbe
Posts: 330
Joined: Sat Jan 17, 2015 3:28 pm
Location: Cheshire, UK

Re: Bias-T powered filter and an Active Antenna on Port B

Postby g1hbe » Fri Feb 02, 2018 7:07 pm

There will only be a problem if the filter cannot pass DC through to your active antenna OR the filter has a DC path to earth, which would short the DC and possibly damage the bias T.
Can I ask is the filter a MW rejector or a MW bandpass filter? And what band are you hoping to listen to?

Cheers

Andy.

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Andy

Paul
Posts: 209
Joined: Fri Feb 17, 2017 9:52 am

Re: Bias-T powered filter and an Active Antenna on Port B

Postby Paul » Fri Feb 02, 2018 7:47 pm

Hi Andy
This is the filter in question (https://www.amazon.co.uk/Distill-Barebo ... B076CVW6LC) and my RSP-2 is currently populated by an active min-whip antenna (the RaA0SMS version, which is pretty useless in the MF Band and lower, but fairly effective at higher frequencies - as an aside - it's originally supplied psu/"isolating transformer" failed and is currently powered reasonably successfully via the Bias-T.
I have a replacement psu on order, but am not yet sure whether or not it will continue in use.
I get, what i believe are excellent results from a second (Ukrainian manufactured) active mini-whip from VLF upwards (on PortA) - my preferred antenna for lower Hf night frequencies and any time (by a small margin) from 8 Mhz upwards (this against a simple 20M long -wire in the open onthe Hi-Z Port) and this is what I was considering using on Port B, perhaps down at least 350Khz, which is the claimed lower roll-off for the filter.
I recognise that Port B may well roll-out sooner than I would wish, but Port A well exceeds 1.5Mhz lower end claimed for it - VLF (what I've seen) is fine and 160M and above loud and clear.
So, in short(?) I was hoping to be able to "investigate" frequencies from 350 Khz upwards, where at my location there is heavy AM breakthrough throughout the band
PS: The elctronic RSP-2 antenna switching is also "complemented" by my having manual switch-gear to permit me additional flexibility.
Thanks for your interest - I'm bowled over by this amazing little box of tricks...

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