Spur Reduction

WA2ZKD

This has been discussed here and on net. Here's a simple way to reduce spurious from your shack going back up the feedline and into the antenna. I used a CATV lightning block and mix-31 ferrites. That point is about mid-point on my feedline to active magnetic loop

ChrisSmolinski

I run my coax feeds underground, and have a similar grounding block set up at each end of the underground run. How much improvement do you note from the addition of the ferrite?

WA2ZKD

it can be hard to quantify but my wspr ranking (number of uniqs) went up several spots since implementating that 2nd ferrite scheme

G8JNJ

The ground spike and ferrites method is certainly better than just using ferrites alone.

But I think you may need more turns through the ferrite, or more ferrite, to get the best performance on the LF bands.

Steve, G3TXQ's (SK) website gives good guidance.

http://www.karinya.net/g3txq/chokes

Regards,

Martin - G8JNJ

WA2ZKD

that was implemented when there was snow on the ground.... more to follow!

Powernumpty

This is one reason why I love the Kiwi, take a laptop/tablet/phone out to the feed line and try stuff while watching the waterfall, harder to do with other receivers.
I ran one channel on a PC set to slow waterfall and then an Android tablet right at the change I was testing, that way when I got back to the PC I could see if my perceived improvements actually showed up on the slow one. Just had to do it when the local QRM was out shopping.

ChrisSmolinski

Yes! The ability to do modifications to antennas/cables/grounding/etc in the field and see the effect in real time using the Kiwi is worth the price of admission by itself! It is a huge timesaver, vs running inside/outside continuously.

Your comment about the slow waterfall speed made me think of something... we can record audio to a file via the browser, what about being able to record the waterfall to a JPG or PNG file? Or even a simple bitmap file if that would be easier to implement? Then it would be possible to look at the entire history of our tinkering, and see the effect(s).

WA2ZKD

Chris... things like kiwirecorder.py and gr-kiwisdr can do some of this stuff

ChrisSmolinski

Good point, WA2ZKD. I may try that today, I want to install some ferrite cores outside and note the effects, if any.

Powernumpty

I do manually save the waterfall from the right click feature but the spectrum needs a screen dump.
It would be nice if the right click to save option could be set to include the date/time in the filename.

I did just test a screen recording program to take interval snapshots but for me it's better to do snapshots just before a change and as quickly as possible after, to avoid condition changes or other QRM blurring any affect.
I do look at the SNR and noise plots on http://sibamanna.duckdns.org/sdr_map.html too, that is good for picking up changes over the week though some terrible noise can just look like a drop in the SNR but only a small increase on the noise plot.
That week of results is half the reason mine is still public even when struggling.

One thing that I found speeded up power supply comparisons is leaving a channel running when the Beagle is powered down, once the PSU is swapped and the Kiwi is back online we can launch a new browser tab by control clicking the green arrow, we should then have a frozen "before" and active "after" tab, keep doing that at each boot/PSU to quickly compare PSU's in the browser.

WA2ZKD

If you can go through the tedium of installing gnuradio and gr-kiwisdr there's a tool that allows you to measure the magnitude of signals and their SNR. It is helpful. As is walking around your house with something like a Sony ICF7600 of equiv.