Messages

271

For Sale / Wanted / Barter / Re: Geiger Counters / Radiation Detectors

« on: August 25, 2019, 1101 UTC »

What is the expected lifetime of the sensor if you have one of these running 24/7?  Will the geiger tube eventually wear out?  If so, are replacement sensors available?

272

Amateur Radio / Re: 3840 khz Bootlegger Net & Jammers (LSB) 05:30 UTC

« on: August 16, 2019, 1254 UTC »

Sadly, this type of behavior goes way back.

http://forum.near-fest.com/index.php?topic=1030.0

Someone once told me that the local hams liked having the one repeater being a “waterhole” for these cretins....it kept them off of all the other repeaters.

273

For Sale / Wanted / Barter / Re: WTB: Skanti R-8003

« on: August 10, 2019, 1547 UTC »

Culpeper is just South of us.  I’m in Fauquier.  Culpeper is just far enough away from DC to miss a lot of the urban blight that flows out from DC.  Fauquier is still holding on to her agricultural roots too.  The other nearby counties have succumbed to the dark side and are well underway in assimilation into the urban mindset.

As you can imagine, the noise floor out here is really low...cows and corn don’t emit much RF.

274

For Sale / Wanted / Barter / Re: WTB: Skanti R-8003

« on: August 06, 2019, 1028 UTC »

I saw you at the hamfest.   Glad to see you got the receiver.

275

For Sale / Wanted / Barter / Re: WTB: Skanti R-8003

« on: August 05, 2019, 0921 UTC »

I saw the same gentleman at the Berryville VA hamfest, but what he had for sale was a R-8001 receiver.  If that is of interest to you I can pass along his contact information.

276

Equipment / Re: AcuRite 02020 Portable Lightning Detector

« on: August 03, 2019, 0944 UTC »

I bought a couple of these too.  I was thinking about how I might use one of them to automatically ground the antenna input on my KiwiSDR receiver...

277

Equipment / Re: AcuRite 02020 Portable Lightning Detector

« on: August 01, 2019, 1235 UTC »

The link below is for a lightning detection chip and it includes some discussion of how the detection algorithm works.  I don’t know if it is the particular one in your device, but the algorithm is probably similar.

https://cdn.sparkfun.com/assets/4/0/5/3/7/AS3935_Datasheet_EN_v2.pdf

278

Longwave Loggings / LF propagation

« on: July 09, 2019, 0907 UTC »

The August 2019 issue of QST has an interesting article on LF propagation.  The author analyzed his experiences on NDBs over 3 years.  I haven’t looked at the article in depth yet but two of his takeaways for his Texas QTH were that the best month was October and that the sunrise enhancement provided the best reception.

279

22 Meter Band HiFER Beacons / Re: P 13555.0 CW 1550 UTC 1 Jul 2019

« on: July 02, 2019, 1042 UTC »

I heard him on too, with a good signal.  Any idea where this one is located?

280

General Radio Discussion / Re: We’re Running Out of Spectrum for Both New and Old Technologies?

« on: June 30, 2019, 1131 UTC »

It is a bit more complicated than that.  Each frequency band has different characteristics.  The 27 MHz frequencies will have poor propagation into buildings for instance, making them less useful for firefighters.  You have to look at what other services are operating on adjacent frequencies and allow for interference to/from them.  Different geographic areas have different users.  A band that seems vacant in Nevada may have many shipboard radars in a coastal area.  You also have to consider the problem of mixing products and whether they will generate problems.  Don’t forget that all the frequency bands are Internationally coordinated.  We try to stay compliant with those agreements.  Also , small chunks of spectrum are less useful than wider chunks.  This is complicated stuff.

Remember when Lightsquared tried to build their system on frequencies adjacent to GPS?  It had the potential of causing severe interference to millions of existing GPS receivers.  It took a huge effort to stop their plans.  Lightsquared’s opinion was that all of these users should upgrade their devices to ones with more robust GPS receivers.  I wondered why their proposal ever saw the light of day.  Didn’t anyone see the potential problems of high power transmitters operating on frequencies adjacent to receivers trying to pick up signals at or below the noise floor?

I worry that the days where hobbyists enjoyed access to large swaths of frequencies are coming to an end.  This latest discussion of changing the status of European hams in the 144-146 MHz band from Primary to Secondary is a prime example.  The people pushing it want to use the band for aviation telemetry services.  I suspect if this comes to pass, hams will be forced off completely due to “safety of flight” concerns.  It may seem like this is a European problem, but if it takes hold in Europe, it will come home to the US eventually.

281

For Sale / Wanted / Barter / Re: WTB: Skanti R-8003

« on: June 30, 2019, 1053 UTC »

I may have seen one of these at the Manassas, VA hamfest, two weeks ago.  It was the first one I have ever seen.  It hadn’t sold yet when I left and it didn’t seem to be getting much interest.  I bought a 75S3 from the same gentleman; I will look inside the manual to see if he wrote down his call.


 

282

The RF Workbench / Re: Audio jacks/plugs as QRP RF wire quick connects

« on: June 20, 2019, 1122 UTC »

Yeah, depending on the connector you can easily start getting loose connections after a few hundred cycles - I did. You can get there very quickly if you switch antennas around a few times a day to check things out.

The number of “mate cycles” a connector is rated can vary wildly.  Some precision connectors are rated for thousands:

https://www.keysight.com/main/editorial.jspx?ckey=632781&id=632781&nid=-11143.0.00&lc=eng&cc=US

Some cheap overseas connectors are seemingly rated for a number less than one.

Most connectors seem to have manufacturer ratings for mate cycles in terms of hundreds of cycles.  This doesn’t necessarily mean that the connector outright fails completely, it means that it doesn’t meet some specification any more (for example, the thickness of the gold plating).   The connector may still be perfectly useful for most applications.

If the connector is abused, all bets are off.  Most RF threaded connectors have torque specs, but you rarely see a torque wrench used.  Some connectors come in 50 ohm and 75 ohm variants.  They look similar, but internal pin diameters are different.  If you mix the two, you may damage one of them.

This article had some good points about connector mate cycles:
https://www.cirris.com/learning-center/product-articles/other-products/227-connector-life-cycles

When you buy hamfest connectors and adapters, who knows what you are getting.  “You pays your money and you takes your chance.”  I try to stay with well known brands like Amphenol, and avoid the ones that look like they have had a rough life.

283

Equipment / Re: On the Importance of Speaker Phasing

« on: June 04, 2019, 1041 UTC »

Disconnecting the cable from scanner and speaker allowed ohming out the input jack, testing verified the speaker was out of phase, go figure. Rectifying the mistake resulted in clean and clear audio.

If your speaker sounds like mush, perhaps you're inverted?

You just had just one speaker connected to the scanner?  How can you have out of phase cancellation with just one speaker?

284

General Radio Discussion / Re: All Digital AM Band? Um, maybe not.

« on: May 12, 2019, 1137 UTC »

I’ve looked at the spectrum of the 820 kHz all digital station many times on SDR receivers here in Northern VA, and the energy is pretty well contained within +/- 5 kHz of center frequency.  It actually looks better than many analogue AM stations as far as not interfering with adjacent frequencies.

You need to look at the required FCC spectral mask.  As I recall, energy on adjacent frequency slots has to be 25 dB below carrier power.   If you have a 10,000 watt station, it could have almost 30 watts of energy on adjacent channels and still be legal.  If you live close to a station, it could certainly seem “wide”.  We have a local station here that seems “wide” but I hesitate to make that claim because even at 15 miles away, I might be seeing legal power levels.

285

HF Beacons / Re: "D" 13527.7 kHz

« on: April 26, 2019, 1014 UTC »

It’s been a long time since I have heard a Single Letter Beacon (SLB).  It used to be they were everywhere.  Now it seems like they are mostly being heard by folks overseas.  But then again, I haven’t been searching them out...