Just this week I finalized my antenna-installation with Denkovi 4-relay-USB-card – and now today I found your page!!! Not good news
for me, but thanks for sharing this info and your experiments!!!! My problem is that I can not test my installation yet.
I try to use Denkovi 4-relay USB-card to switch 4-different antennas for Medium Wave DX-listening. We have 3 longwires (800 m each)
with coax-feeds. The installation date will be 1-3.11.2013 in the noise-fre country-side in Mid-west Finland. I can not pre-test my box
before because my rx-equipment (Perseus) is elsewhere now.
I have not done it like you have. I change my antenna-relays by Denkovi-relays (I have photo of it), so the RF is not going through
Denkovi-relays, only minus of 12V antenna relays. (So, I can try to move Denkovi-card inside PC forexample). However, I am now
very concerned of this possiblity to have interference.
On what frequencies the interference was worst? Signal peaks in every 1 kHz??? What noise-level above rf-noise??
Even more noise when software started???
We need extremely silent band to MW so any leak from usb-card is not tolerable.
Harri, thanks for dropping me a line. I wouldn’t give up hope on your installation – mine is the absolute worst case because I’ve stripped the RF lines of all their shielding when they run through this box, as close as they can get to the USB device. Since posting this I’ve also overcome some noise problems with a USB-serial converter and my Elecraft K2 by adding ferrites and changing USB port on the computers that were in that setup so I feel a bit more confident about tackling USB noise.
The most important thing is that you’re using the correct approach of coaxial relays for your signals lines. If you keep the USB connection between Denkovi board and PC as short as possible and add ferrites at both ends of that cable, then separate the coaxial relay and RF signal lines as far from the PC/Denkovi as possible. The noise I had was pretty bad, I can’t remember the levels but remember here my signal lines were unshielded and trapped in a metal box on the same PCB as the interference source! I know it was bad but, like I said, it was a very rough quick experiment to see if I could get away with it. I’m sure when I get a coaxial relay it’ll be OK.
You’re setup sounds superb! I found your homepage online – VERY interesting stuff. Looking forward to hearing how you get on.
Hi Andy!
Just this week I finalized my antenna-installation with Denkovi 4-relay-USB-card – and now today I found your page!!! Not good news
for me, but thanks for sharing this info and your experiments!!!! My problem is that I can not test my installation yet.
I try to use Denkovi 4-relay USB-card to switch 4-different antennas for Medium Wave DX-listening. We have 3 longwires (800 m each)
with coax-feeds. The installation date will be 1-3.11.2013 in the noise-fre country-side in Mid-west Finland. I can not pre-test my box
before because my rx-equipment (Perseus) is elsewhere now.
I have not done it like you have. I change my antenna-relays by Denkovi-relays (I have photo of it), so the RF is not going through
Denkovi-relays, only minus of 12V antenna relays. (So, I can try to move Denkovi-card inside PC forexample). However, I am now
very concerned of this possiblity to have interference.
On what frequencies the interference was worst? Signal peaks in every 1 kHz??? What noise-level above rf-noise??
Even more noise when software started???
We need extremely silent band to MW so any leak from usb-card is not tolerable.
73s
Harri Kujala
Naantali
SW Finland
Harri, thanks for dropping me a line. I wouldn’t give up hope on your installation – mine is the absolute worst case because I’ve stripped the RF lines of all their shielding when they run through this box, as close as they can get to the USB device. Since posting this I’ve also overcome some noise problems with a USB-serial converter and my Elecraft K2 by adding ferrites and changing USB port on the computers that were in that setup so I feel a bit more confident about tackling USB noise.
The most important thing is that you’re using the correct approach of coaxial relays for your signals lines. If you keep the USB connection between Denkovi board and PC as short as possible and add ferrites at both ends of that cable, then separate the coaxial relay and RF signal lines as far from the PC/Denkovi as possible. The noise I had was pretty bad, I can’t remember the levels but remember here my signal lines were unshielded and trapped in a metal box on the same PCB as the interference source! I know it was bad but, like I said, it was a very rough quick experiment to see if I could get away with it. I’m sure when I get a coaxial relay it’ll be OK.
You’re setup sounds superb! I found your homepage online – VERY interesting stuff. Looking forward to hearing how you get on.
73!
Andy