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Latest Posts

Topic Author Posted On
cme 9-12-14 WA1HEW 5 days, 6 hours ago
We have recently had an X-class solar flare (1823 9/10/14). Check, for example. That's a very big flare. The UV radiation and X-rays will make very high D-layer absorption that kills the HF bands pretty well -- on the sunlit side of Earth. You can see that in real time at . I would expect it to die away after a number of hours.

The X and UV effects of a flare are pretty much instantaneous. There may also be a Coronal Mass Ejection (CME) that travels more slowly. CME's are directed and very often miss the Earth entirely. If this one hits us, it may produce a serious geomagnetic event. That will upset HF propagation (again), and it may cause problems for power transmission lines.

73 Martin AA6E
Broadcast quality headphones patterson725 2 weeks, 2 days ago
Rick, I agree that headphones are often the best way to listen to ham communications. (And, a side benefit, it can help preserve the peace, domestically.)

When you say "broadcast quality", it seems that you're looking for high fidelity 'phones. They can work, but really most folks are probably better off with "communications quality" -- optimized for speech and CW signals, generally in the 200 - 3000 Hz range. Any super low bass or high frequency is just going to make things harder for you, since it will increase the noise level without adding any intelligibility.

Having said all that, headphones intended for stereo music are a lot easier to find at a reasonable price. I just would not go for "premium" products. There are a bunch of other issues, though:

Impedance: Headphones for stereo (hi fi) use may have low impedance, like 4-8 ohms. That's often too low for best work with communications receivers. Higher impedance is probably better. (Check what your receiver manual says.)

Comfort: This is a big one. You have to be able to tolerate your 'phones for hours at a time. Be sure they are adjustable to fit, etc.

Style: There are types that just fit (loosely) on your ear without much cushioning, and others that have large cushions. This will affect comfort, but another benefit of the ear-surrounding cushions is that it cuts down acoustical noise from your environment. That can be important.

I use Sennheiser headphones with over-ear cushions. They're very nice, and I'd tell you the model number, but they don't seem to have a label!

73 Martin AA6E
Experimental QRM triangulation tool. W7KKX 3 weeks, 2 days ago
Nice idea! Alas, my beamwidth on 20M is many degrees, so it would be hard to determine a target bearing very accurately. You need receivers located on a wide range of bearings, etc. Antenna arrays (4 squares?) that can be accurately nulled might give better results than simple beams. (But how do you calibrate them?)

It will be interesting to see what you can do with ordinary equipment -- and ordinary hams!

73 Martin AA6E
virtual radar WB4URP on 3/8/14
I agree it's not there. You would need to contact the author or the sdrsharp project.

73 Martin AA6E
What is an accepted range for a DX contact? WN6WJN on 17/4/14
For the HF bands (below 30 MHz), usually called "short wave", we have long-distance propagation thanks to bouncing signals off the ionosphere. On these frequencies, the usual idea of "DX" is contacting someone in another country. So US-Canada is "DX" by this measure, even if the distance can be very short. And Maine to California would not be DX.

ARRL has the concept of a "DXCC entity" and people try to contact as many of them as possible. They are generally countries, but some non-countries, like Alaska and Hawaii, are considered separate entities. Check out

73 Martin AA6E

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