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VLF/HF Loop Antenna


Mike Royal
 

A UK based newbie here with a couple of questions I wonder if anyone can help with, please.
I have just placed an order for the VLF/HF Loop Antenna to be used with an RSP1A SDR.
1. Can anyone recommend a quiet usb 5v power supply for the Bias T base unit?
    I seem to recall Chris Moulding mentioned somewhere about finding a suitable mobile phone charger.
2. Is anyone successfully using the Bias T setting in the SDRUno programme to directly power the head unit?
Thanks, Mike


Paul Newland
 

Hi Mike
I have one of the “original” VLF/HF amps - powered by usb. I have since bought a HF/VHF bias-t powered unit.
This works very well indeed and I believe that you might be better off with a bias-t powered version that is now available. But ask Chris.

On Sun, 19 Jan 2020 at 14:39, Mike Royal via Groups.Io <mikerr44=yahoo.com@groups.io> wrote:
A UK based newbie here with a couple of questions I wonder if anyone can help with, please.
I have just placed an order for the VLF/HF Loop Antenna to be used with an RSP1A SDR.
1. Can anyone recommend a quiet usb 5v power supply for the Bias T base unit?
    I seem to recall Chris Moulding mentioned somewhere about finding a suitable mobile phone charger.
2. Is anyone successfully using the Bias T setting in the SDRUno programme to directly power the head unit?
Thanks, Mike

--
Best Wishes
Paul


Chris Moulding
 

Hi Mike,

If you are planning to use the head unit of the Loop Antenna Amplifier with a SDRPlay receiver you will probably be better off with the HF/VHF version as the head unit has a higher gain. I can always change your order for you if you want.

Regarding 5V USB supplies since we have started adding a 1000 uF capacitor to the base unit it's reduced the noise from nearly all USB power supplies so that it is below the external noise picked up by the loop. I found two cheap 5V USB supplies for LED lights that generated noise but they now work well with the extra smoothing capacitor.

The 5V USB supplies intended for mobile phone use are usually made to a higher specification as even unscrupulous manufacturers draw the line at having to replace a lot of new mobile phones!

Regards,

Chris


Paul Newland
 

You have the definitive answer Mike!

On Sun, 19 Jan 2020 at 14:51, Chris Moulding <chrism@...> wrote:
Hi Mike,

If you are planning to use the head unit of the Loop Antenna Amplifier with a SDRPlay receiver you will probably be better off with the HF/VHF version as the head unit has a higher gain. I can always change your order for you if you want.

Regarding 5V USB supplies since we have started adding a 1000 uF capacitor to the base unit it's reduced the noise from nearly all USB power supplies so that it is below the external noise picked up by the loop. I found two cheap 5V USB supplies for LED lights that generated noise but they now work well with the extra smoothing capacitor.

The 5V USB supplies intended for mobile phone use are usually made to a higher specification as even unscrupulous manufacturers draw the line at having to replace a lot of new mobile phones!

Regards,

Chris

--
Best Wishes
Paul


Mike Royal
 
Edited

Thank you for all the replies folks.
As far as I understand it, the VHF/HF loop antenna misses out on Long Wave.
I am looking for a loop antenna with good coverage of Long, Medium and Short Wave.
Before I broke it (don't ask), I had a MLA-30 loop antenna. I was using that on SDRUno's Bias T setting and it did a pretty good job on Short Wave. No so good on Medium Wave and very poor on Long Wave.
Thanks, Mike


Paul Gulliver
 

Hi Mike,

The reason your MLA-30 didn't work well at lower frequencies may be explained here https://groups.io/g/CrossCountryWireless/message/6551
I also have a MLA-30 and using the supplied bias tee works well at the NDB frequencies - that's around 300KHz - I haven't tried it at lower frequencies.

Whatever amplifier you choose, for the lower frequencies always use an external bias tee.

Paul


Mike Royal
 
Edited

Hi Paul,
Thank you. That link you gave was most informative.
I did very briefly try using the the MLA-30 with the supplied Bias T, but the noise floor went up considerably.
Maybe I should have concentrated on finding a quieter power supply for it.
I think also I was trying to use the minimum number of parts, Laptop running SDRUno, RSP1A and Loop head.
Cheers, Mike


istvan.fuley@...
 

Hello group members,
Another newbie here, sorry for hijacking this thread, but my question is related to the OP's:
couple of weeks ago I ordered from CCW a HF/VHF loop antenna amplifier. Altough I sent an email to Chris specifying that i need a HF/VHF version which I'm willing to power by an SDR with bias tee, I received last week a VLF/HF version of the amplifier. As I'm mainly focused to HF, I can live with it.

My question is: can I power this amplifier (version 2020 VLF/HF) directly from RSP1A's bias tee, or do I need to use the base unit and separate USB power source?

Thanks, István


Chris Moulding
 

Both the VLF/HF and HF/VHF versions can be powered directly from the SDRPlay bias-tee but as the choice of capacitors and inductors in the bias-tee were intended for GPS and L band use the frequency response rolls off around 2 MHz.

Regards,

Chris