Re: Airspy HF+


jdow
 

Weeeeellllll, AirSoy 1 benefited a lot from some basic EMI treatment. AirSpy 2 benefited but not as much as 1. What I did is take a suitable tool and GENTLY flake off a narrow band around the edges of the inside of the front and back panels. I also flaked off the paint from the thin edges of the box proper. That way I got metal to metal contact all around the box. (Yeah, it's aluminum; but, it did make difference.) Then I gently flaked paint a little less than the gold lockwasher's diameter around each SMA connector hole on the outside face. And I flaked away some paint on the inside around the USB connector. I arranged for some braid to get pinched by the USB connector and reassembled the box. On R1 I got a good 30 dB improvement. On R2 it seemed to be somewhat less.

Once that is done audiofeelie grade USB cables are nonsense. But good size (3/8" hole) ferrite sleeves can make an additional difference if applied both to the antenna feed and the USB cable. You can get decent help at UHF and higher frequencies with the the smaller 1/4" diameter ferrite sleeves. For AirSpy plus Spyverter I'd use the bigger ferrites. For UHF and up the littler sleeves may do better. Some of the trick is picking the ferrite material to use. If Ambidon is still in business.... They are so visit "www.amidoncorp.com/" . In the past they've been quite helpful. And they are (were) ham radio friendly.

{^_^} Joanne

On 2017-08-06 13:48, prog wrote:
Everything is shielded. There's only one way to get your external noise inside the RF section (under the metallic can), and its' the RF input.
In the other hand, there are less performance constraints on the USB link since we are only streaming 24.5 Mbps. Of course, you will always find more expensive snake oil audiophile grade usb cables in the Internet. I'd say put that money on a good antenna and better cables :-)

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