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Messages - ak7v

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1
HF Beacons / Re: New Beacon "L" on 4096.12
« on: May 01, 2021, 0247 UTC »
Loud and clear here in Wrightwood CA

2
HF Beacons / Re: New whooper beacon on 4095.65
« on: April 29, 2021, 0256 UTC »
.......... my Kiwi SDR in Wrightwood, CA. http://ak7v.hopto.org:8073/

I forgot to ask for tech details on your SDR. Please share!

Jim

Sure! It’s here at my place in Wrightwood, CA at 6275’ ASL and I’ve had it working for about a year, but just put it online for the world a few weeks ago. It’s a KiwiSDR with a home brew 5v linear power supply. Antenna is a W6LVP active loop on a speaker stand in my backyard, fed with about 25 feet of RG-6.

Relatively rural area, but houses are close together so there is some domestic RFI. I don’t seem to hear much above 15MHz - not sure if that’s the antenna, recent propagation, and/or being tucked up against a mountain. At some point I will put some wire up in the trees and see how those compare. But it seems to work great for MW and pretty well for the lower HF bands.

I used to live on a few acres and had bigger wire antennas (plus a vertical I transmitted with) and used my Perseus to listen. This setup now isn’t quite as good, but for the space I have, it’s acceptable.

Thanks for your interest and enjoy the SDR!

3
HF Beacons / Re: New whooper beacon on 4095.65
« on: April 22, 2021, 2329 UTC »
PV could be solar irradiance in watts per square meter.  That tends to range from 0 - 1200 or so.  Maybe someone already brought that up.

I almost always hear that beacon pretty loud on my Kiwi SDR in Wrightwood, CA. http://ak7v.hopto.org:8073/

4
Nice signal in Wrightwood, CA. S8-9

5
Yep, you were right - swapping out the 74HC02 fixed the issue.  I gotta be more careful!

Thanks

6
The RF Workbench / Help with 22m beacon kit from Black Cat Systems
« on: March 10, 2021, 2317 UTC »
Hello,

I ordered a 22m beacon kit years ago and finally got around to putting it together.  It works great as long as my supply voltage is 4v or less - nice clean sine wave on frequency, keying from uC works.  Anything above 4v, and it will tend to oscillate at a higher harmonic (and not make it through the output filter, thankfully).  When I first power it up, it'll oscillate on the crystal's fundamental, but if I adjust the pot, or "key" the microcontroller (either with the actual microcontroller or manually with a wire from pin 6 to VCC or GND), the 74HC02 will jump up to a harmonic and stay there until I cycle power to the board.

Anything I can do or anywhere I should look to diagnose/fix this problem?  I'm powering it off a bench supply for now, no regulator installed on the board (just jumper).  No extra caps, although I played with a few values in C16 without any change in this behavior.  I've checked my component placement and all looks well.  I measured 4.98v in the initial voltage check prior to installing the 74HC02.

If I run at 4v or lower, it functions exactly as it should.  This probably won't be a real problem since I plan on using a solar light w/ battery to power it, but I'd like to learn and understand what's happening and how to fix it.

Thanks!



7
The main practical difference will be a change in feedpoint impedance.  An inverted vee is closer to the 50 ohms that most ham radio transmitters prefer (I'm not sure what your TX is looking for).  It's also usually easier to erect, so it's a popular configuration.  I've never heard of anyone intentionally putting a dipole 5x the wavelength high.  To me that seems excessive.  At 13Mhz putting the apex of an inverted vee up 30-40 feet is good for near-omni radiation at a reasonable take-off angle.  Beyond that you start getting into diminishing returns for the amount of effort.

If you want to get fancy, there is free antenna modeling software out there what will show you the radiation patterns of different configurations at different frequencies.  EZNEC and 4nec2 are examples.  Antenna theory is a deep and complex subject, but there are answers out there! 

8
For Sale / Wanted / Barter / Wanted: SDR
« on: May 12, 2015, 1618 UTC »
Hello,

So I've recently discovered the joys of using an SDR thanks to an Afedri SDR Net that I purchased.  I live in a quiet area and have a good antenna, and although I enjoy the Afedri, I would like to get something a bit more capable.  Does anyone have a higher-end SDR that they're interested in selling?  I'm thinking Perseus, Winradio, QS1R, RFSpace unit, etc?

Thanks

9
SDR - Software Defined Radio / Opinions on SDR-IP?
« on: April 29, 2015, 2124 UTC »
I see an SDR-IP for sale for under $1000 on a popular auction website -- seems pretty cheap.  I've been considering the QS1R but this RfSpace unit has caught my interest.  Anyone able to compare these units?  Any first-hand experience?

Thanks

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