Messages

196

Equipment / Re: Discone antenna mounting

« on: February 10, 2020, 0941 UTC »

You can't screw a PL259 into an N type socket.

You can force a PL259 into a female N connector...and you will permanently destroy the female N connector when you do.  The center conductor pin will be deformed or broken in such a way that you can’t repair it.  Check your antenna for damage.

Something is wrong when you start talking about having to “thicken up the center conductor with solder”.  It sounds to me like the antenna is damaged.
 

197

General Radio Discussion / Re: Another Pride of China portable radio

« on: February 09, 2020, 1252 UTC »

Chinese radios are often like Harbor Freight tools.  They may be cheap and poorly made - but there are tasks they are perfectly suited for.

198

SDR - Software Defined Radio / Re: First SDR receiver

« on: February 09, 2020, 1237 UTC »

The waterfall is a game changer.

A long time ago I had a Heathkit HO-13 spectrum display connected to my SB-303. This only showed the real time spectrum maybe +/- 50 kHz of what you were tuned to.  It was interesting, but not terribly useful and I soon traded it for something else.

Fast forward a few decades to the era of DSP radios with not only real time spectrum display, but the waterfall that allows you to see things that happened seconds or minutes ago.  Now you are seeing signals that you would have missed in the past - either because you weren’t tuned to that frequency or they were too short in duration.  You are also realizing that something you had dismissed as RFI was in fact a wide band data signal - because you can now see the entire spectrum of the signal.

DXing without a waterfall is like driving while wearing horse “blinders”.  You won’t go back.

There is only so much you can do as far as being to recognize modulation types off of the waterfall.  CW, RTTY, AM, or SSB are pretty easy, but the digital modes are another matter.  This makes sense when you realize that fundamentally many digital modulation schemes are similar.  For instance COFDM is used in many waveforms - but the number of sub carriers and the spacing might be different.  On your waterfall they will look similar.  There are programs available in the commercial market that will perform signal modulation identification but the pricing is way beyond what most of us can afford.

I saw a posting recently by Josh where someone had written something to try to do this.  I have no idea whether it works or not.

https://www.rtl-sdr.com/shazam-style-automatic-signal-identification-via-the-sigidwiki-database/

199

SDR - Software Defined Radio / Re: First SDR receiver

« on: February 08, 2020, 1053 UTC »

The RSP2 is a good SDR.

One thing to keep in mind about it (and most any SDR) is that if a strong signal is present at the input, you may see weird artifacts at other frequencies.  If you have a strong local AM, FM, TV, LMR, etc station nearby, you may need an additional filter.  The RSP2 has filtering built in, but some locations require a little more.  Fortunately, inexpensive filters are available.  Try it out and see if it this is needed.

Along the same lines, SDRuno has a lot of adjustments to tweak.  If performance doesn’t seem very good, it is more likely that some SW parameter needs adjusting rather than the RSP2 being broken.

200

Equipment / Re: Copper Clad Steel

« on: February 07, 2020, 1224 UTC »

An update from Owen, this time looking at ladder line.  Maybe not as bad as previously thought, but still something to be aware of.

https://owenduffy.net/blog/?p=16920

201

Propagation / Re: Grey line map (real time)

« on: February 05, 2020, 1156 UTC »

This is something to be aware of as some propagation prediction programs are using old SSN lookup tables.  This was recently mentioned here:

https://swling.com/blog/2020/01/ham-cap-and-voa-prop-fixing-ssn-look-up-files/

202

Propagation / Re: Grey line map (real time)

« on: February 04, 2020, 1100 UTC »

I use one of the online ones. A solar propagation site has one that works.

http://www.spacew.com/www/realtime.php

While the grayline may be correct, don’t be fooled by the rest of the data at the map link above.  It has been a long time since we have seen a SSN of 86.

"SSN"? I don't even see a reference to an SSN (whatever that is) on the page anywhere. It has the grey line, radio auroral zones, and MUFs delineated and mentioned, and that's about it.

If you look at the graphic, there is a black bar at the bottom where they show the Smoothed Sunspot Number (SSN), which is used to calculate the MUF.

The true current value is on the order of “5” or so.  You can tell that they are using the wrong number because the MUF values the graphic has are unreasonably high.  A SSN value of 86 would have been reasonable 5 years ago - not today.

You can find better numbers for SSN here:

https://www.sws.bom.gov.au/Solar/1/6

203

Amateur Radio / Re: HT Antenna

« on: January 30, 2020, 1339 UTC »

KX4O works as an antenna engineer.  You may find his comments helpful.

https://www.hamradio.me/antennas/ht-antenna-comparisons.html

204

VHF/UHF Logs, including satellites and radiosondes / Re: FLTSATCOM

« on: January 30, 2020, 1319 UTC »

 FLTSATCOM uses geostationary satellites...there is no “pass”...either your location is in the footprint or it isn’t.  You will hear some clear voice traffic (mostly Brazilian pirates) but most traffic will be encrypted digital.

205

Longwave Loggings / Re: New to longwave

« on: January 30, 2020, 1304 UTC »

If you can’t find your LPF there are a number of designs available on the Internet.  They are very simple to build.  I agree with JFarley and Pinto - if you are serious about LF you need one.

I use one from rescueelectronics.com (though I am not sure if they are still in business - they aren’t answering email.)

One other thing I have discovered to be essential (at least for my installation) are common mode filters on the feedline, at both the antenna and at the receiver.  I was surprised at how much local EMI they cleaned up. They have to be rated to work at LF - your typical ham CM filter stops at 160M. (Palomar Engineering has models rated to go to 100 kHz, but they are very slow on shipping.)

You can build your own LPF and CMF for little cost...a fraction of what buying commercial products will cost.


If you build your own, make sure you use Type 75 or Type 77 ferrite for the CM filter.

206

Equipment / Re: Dual band vertical Vs Discone

« on: January 29, 2020, 1251 UTC »

I think a good discone is useful to have as a general purpose antenna.  You can never have too many antennas.

The Diamond D777 is an antenna for the VHF (118-136) and UHF (225-400) aviation bands.  You can find them at Ham Radio Outlet.  I have one but haven’t installed it so I can’t speak to its performance yet.

https://www.hamradio.com/detail.cfm?pid=H0-012019

207

General Radio Discussion / Re: The Ultimate Pride Of China Portable Shortwave Radio for $9.59

« on: January 26, 2020, 1426 UTC »

The solution is obvious, you buy glue from the "Department of Life" section: http://www.winningmart.com/category-362-b0.html

Oooh...blue and red glue...I don’t see that in my local box store...

208

General Radio Discussion / Re: The Art of Electronics: The x Chapters

« on: January 26, 2020, 1422 UTC »

Thanks for posting this.  I had the main book, but didn’t know about the “X Chapter” volume.  The chapter on transient supression devices alone was worth the price to me.

209

Amateur Radio / Re: Digital modes on HF... love it or hate it.

« on: January 26, 2020, 1414 UTC »

On  like note, the HAM repeater traffic I hear is always the same few people who know each other locally, not newcomers or even people driving past the area - however that does happen. I suppose this is to be expected among friends.

Many clubs, repeaters, or nets are not welcoming of newcomers.  I don’t think they are necessarily hostile, they just don’t take that extra step of creating a welcoming, fun atmosphere that makes people want to be there.  I am as guilty as the next guy of only talking to my friends and ignoring others.

The local club here has a reputation of being a fun place to be and we have a lot of new blood.  It wasn’t always that way - no one said a word to me the first meeting I went to years ago.  Today we have one guy who goes out of his way to greet all newcomers - whether on the repeater or at the meetings.  It’s not an “official” job...it is just his nature.  Another club I was once a member of was in an area with a transient population.  They went so far as to station a couple of guys near the front door to look for new faces and welcome them to the meeting.

It’s funny how a single individual can be the catalyst that makes a club successful...or a poison pill that drives people away.

210

General Radio Discussion / Re: The Ultimate Pride Of China Portable Shortwave Radio for $9.59

« on: January 26, 2020, 1345 UTC »

Mine rattles.  The speaker is loose.  And there is a crack in the case.  You can’t get a quality $9.59 radio anymore <G>.