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4

At 27 MHz and a distance of 1000 km, propagation will be the main determinant of the possibility of communications. Propagation will primarily be a factor of time of day and the sun spot conditions. You can get a fairly accurate estimate by using propagation prediction sites such as VOACAP. If your interest is exchanging messages between stations, one of ...


4

It is equally important to consider the pattern of the antenna. If you hang a 1/2 wave antenna vertically, there will be minimal radiation in the earth facing direction. This will be most problematic for HF NVIS contacts. You may also wish to check the RF resistance of 38 AWG wire on 2 meters. I roughly calculate it to be > 100 ohms at 146 MHz for 10 meters ...


4

The output impedance isn't especially important: in fact I believe it uses a nonlinear amplifier so the concept doesn't really apply. What does matter is the intended load impedance, which for any amateur radio application you can assume to be 50 ohms unless otherwise specified. To verify, I modelled the low-pass filter part of the circuit from the manual: ...


4

My guess, looking at WSPR reports, is that, on average (median), WSPR beacons are transmitted at power levels maybe in the range of 10 to 30 dB lower than the median of FT8 transmissions. e.g. 20 dBm Raspberry Pi hat vs. 37 dBm QRP SDR, or 30 dBm WSPR appliance vs 50+ dBm desktop transceiver and/or QRO amp, as bracketing examples. So the reported 10 dBm ...


3

I’m going to throw the HF vertical’s hat in the ring, too. Something like an R5 or R7 (or HF9V or similar), that can be used on the higher HF bands and 6m. They’re omnidirectional, which is either a good thing or a bad thing, and with a good set of radials they perform well for both receive and transmit. They might be a little expensive for a simple ...


2

This sounds like a perfect application for the Discone antenna: "Skeletonizing" the disc and the skirt make it amenable to construction with wire and/or tubular elements. The skirt is insulated from the disc and is angled downward from the horizontal plane; this insulator is the location of the feedpoint. There are several commercial suppliers of similar ...


2

A short dipole or small loop is a good choice for a receive-only antenna that works over many bands simultaneously. The trick is to make an antenna that's equally bad everywhere. If you try to match a short dipole with a loading coil, or a small loop with a tuning capacitor, you end up with a very narrow-band antenna. So instead you don't try to match it at ...


2

I would say, your task is a challenging one, but not unsolvable. 27 MHz CB radio band should work similar to 10m amateur radio band. I suggest to start with simple experiments. For instance, solder a simple oscillator. In my experience Clapp oscillator is quite simple to solder, see schematic in this article https://eax.me/clapp-oscillator/ . Then add a 555 ...


2

I'm neither an electrical engineer nor a software-defined radio expert, but I have used WSPR, so I'll have a go at answering your question. You're correct that WSPR transmissions on 30m are centered around 10.1402 MHz, but the WSPR 2.0 User's Guide says that the passband is about 200 Hz wide since the software will generate tones between 1400 and 1600 Hz, ...


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