smg

Passed!

I'm officially now ZL1SXG

:-)

Mounted on the garage roof

Well I don’t live far from our local industrial area and there are plenty of hvac companies there. Ask and thou shall receive

BEHOLD!

Not to sure

you are welcome to look at mine.

You might find asking in the Loop Antennas group over at https://groups.io/g/loopantennas

So, some really un-scientific anecdotal evidence (listening and comparing RSSI / S-Meter levels on various stations, including UTC, 20Mtr HAM, various broadcast bands, its a tight race. The MLA 30 gives a few DB more signal, however I have the gain turned up on it. The Apex whip has an inline galvanic isolation transformer on it, and the noise floor between them both is almost indistinguishable.

I'm quite amazed at the apex 303, and the fact it is a short whip totally passive.

Time to get an antenna switch.

Im only using an cheap magnetic loop off Ali Express.

Its 6pm NZ time.

Loving the Kiwi :-)

John already has some documentation on antenna switches.

I started making my own code to work with a 3rd party switch

https://github.com/smegoff/RAAS-4-Scripts

Also, check out this thread

https://forum.kiwisdr.com/index.php?p=/discussion/3249/what-antenna-switch

Hopefully this helps

The displayed waterfall span at zoom level z is

BW = 30 MHz / 2^z.

Given a centre frequency cf (in kHz), the visible frequency limits are:

BW_kHz = 30000 / (2^zoom)
f_low  = max(0, cf - BW_kHz/2)
f_high = min(30000, cf + BW_kHz/2)

At zoom=0 the Kiwi always shows the full 0–30000 kHz waterfall, regardless of cf. For zoom >= 1, the span centres on cf (clamped so you never go below 0 or above 30000 kHz). (KiwiSDR)

Example with your numbers

• Command: SET zoom=0 cf=7550.000000
• Waterfall span: 0–30000 kHz (full band). (KiwiSDR)
• Command: SET zoom=1 cf=7550.000000
• BW_kHz = 30000 / 2 = 15000
• f_low = 7550 − 7500 = 50 kHz
• f_high = 7550 + 7500 = 15050 kHz
• So you’ll see 50–15050 kHz.

Why this matches what the Kiwi does

• Zoom levels are power-of-two subdivisions of 30 MHz (e.g., WF7 ≈ 234 kHz, WF8 ≈ 117 kHz), which is exactly 30 MHz / 2^z. (KiwiSDR)
• The waterfall data is 1024 bins wide; bin width is Δf = BW/1024. At zoom=0, that’s about 30 kHz/bin. At the max zoom (z=14), Δf ≈ 1.8 Hz/bin. (KiwiSDR)
• In the protocol/URLs the frequency values are in kHz (e.g., ?f=22500 for 22.5 MHz), same unit used by the cf you’re sending. (KiwiSDR)
• The Kiwi’s nominal coverage is 0–30 MHz (some installs set 32 MHz), hence the clamping in the formula above. (RTL-SDR, kiwisdr.com)

Mapping bins to frequency (handy for your Java code)

If you index bins i = 0..1023:

Δf = BW_kHz / 1024
bin i spans [ f_low + i*Δf , f_low + (i+1)*Δf )   (in kHz)

That should make your prototype line up perfectly with what the Kiwi sends.

John (Kiwi’s author) explicitly describes the zoom behaviour and bin counts here: https://forum.kiwisdr.com/index.php?p=%2Fdiscussion%2F1472%2Fsetting-dispalyed-bandwidth

Yup you are right.

Its still going strong this morning. Might see if other kiwis further afield are picking it up.

I've been through a few iterations of Power Supplies, including what I thought was an adequate linear one, that ended up not firing up the Kiwi first time round (using the Kiwi supplied cable too!), and running hot, to settling on this:

https://www.aliexpress.com/item/1005006697287204.html

It runs cool, and seems to meet the demands of the Kiwi with no start up issues at all. I've had it open and its well-made and very clean and uses high quality components.