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Messages - redhat

Pages: 1 ... 5 6 7 8 9 10 11 12 [13] 14 15 16 17 18 19 20 21 ... 106
181
Equipment / Re: Why 50 ohm coax cable?
« on: January 08, 2021, 1738 UTC »
The mismatch between 50 ohm and 75 ohm coax will create a SWR of 1.5/1.
Some hams will obsess over this in search of the perfect 1:1 match.
However, a SWR of 1.5/1 works out to a reflected power of only 4%.

See the ARRL Antenna Book Chapter 23, the section on Standing Waves,
they got a nice graph in there showing the how much power is reflected
for a given forward power and SWR.

The amount of radiated power wasted is not the primary concern when dealing with VSWR.  I will apologize ahead of time for derailing(at least temporarily) this thread  ;D
In the commercial world, best reliability comes with systems designed for low VWSR.  High VSWR is not only wasteful of TPO, but also causes hotspots in the line.  When you have perhaps 20% overhead on line capacity because the next size up is prohibitively expensive, low VSWR needs to be maintained to keep the line safe.  We are also in the era of solid state transmitters, which don't like VSWR.  Even commercial AM's will only operate at full power up to 1.5:1 before folding back.  Typically in commercial FM service, the antenna match at the output of the transmitter is under 1.1:1.  High VSWR in TV service causes problems with intermodulation  and spurious emission in the power amplifiers, so they tend to run lower, typically under 1.05:1 to maintain mask clearance.  The gear I build is designed with enough voltage rating to handle full power operation at up to 1.5:1.  We are on the bleeding edge of technology, and until we have transistors capable of 2KV or better Vds ratings, this will be the ceiling.

All of this, of course, is completely unrelated to receive antenna performance, where major shifts in impedance or standing wave will have little affect on the ability to receive a signal.

+-RH

182
Huh? / Re: Is It Time for Radio to Restore Dynamic Range?
« on: January 06, 2021, 1801 UTC »
Being on the inside, I have seen a lot of good things over the last decade of engineering.  One thing, bought music libraries are often lossless.  Hard disk space is now cheap enough that lossless makes sense.  Of course, if your playing pop, hip-hip, or a lot of similar genres that makes use of samples, what are you really getting with lossless?  Program paths are often PCM, particularly in larger markets.  Smaller markets are often running analog STL shots, so little has changed there.  Processing has gotten better too.  Most of the new flagship processors incorporate declippers, and all you have to do is wait for a Red Hot Chili Peppers song to come on and see if its being used  :P

I read something recently about the loudness war being over, as many online streaming entities are pushing the volume of hypercompressed content down, seemingly rewarding material with dynamics by playing them louder.  I hope the trend continues, and I have seen some indy stuff lately that looks less like a box on the waveform view of any DAW.  Unfortunately the music distribution system is moving farther and farther from a lossless world, and often the only version you can get of a song is MP3.  At least bandcamp would let you have a PCM version of a song if you wanted, but again there is no way to tell what the original source was.

As long as people are content to listening to music on the subway with tin can ears, the music industry will pump out content geared toward the lowest common denominator.

+-RH

183
General Radio Discussion / Re: FCC REPORT ON PIRATE RADIO ENFORCEMENT
« on: January 05, 2021, 2311 UTC »
I dunno, OFCOM has a pretty bad reputation as well.  Prison time for involvement in FM pirates?  At least we don't have that here...yet.

+-RH

184
Nice to see that finger pointing journalism hasn't gone out of style ::)

+-RH

185
Equipment / Re: The Best Active Loop Antenna 2019 = MLA-30?
« on: January 04, 2021, 0620 UTC »
I bought one of the MLA-30+ about a year ago.  Compared to the 30' vertical in the backyard, the MLA-30+ is about 20dB noisier.  Signals that are discernable on the vertical are buried in noise with the loop.  The noise floor of the amplifier is just too high, and that is with a home made power injector, not the provided one.  I love the loop concept, but the front end needs work, and there are many solutions out there that I'm sure perform better.

...But for the price, it's hard to beat.

+-RH

186
QSLs Received / Re: X-FM 25 August 2019 eQSL and play list.
« on: January 04, 2021, 0614 UTC »
Your welcome!  It takes about 3 hours of computer time to manually transcribe the log, sort out email and log posts, then assemble the QSL master, run them, and email...per show.  It works out to a solid 40 hour work week once a year.  Putting the annual disc together takes another several hours.  It is work.

+-RH

187
QSLs Received / Re: X-FM 25 August 2019 eQSL and play list.
« on: January 04, 2021, 0108 UTC »
And with that, 2019 is 'in the can'.  We issued 194 QSL's for 11 shows.  I will start working on the 2020 QSL's next month, and hope to have any postal items rolling soon after.

Thank you all for your reports and email!  We'll see you soon with a decade in music recap show live from 'somewhere under the stars...'

+-RH

188
Peskies / Peskies 4188 LSB 3 JAN 2021 0005z+
« on: January 03, 2021, 0016 UTC »
Weak but audible.  Presumed spanish.

+-RH

189
First run with the new Airspy HF+ on a linux PC and GQRX.  Homemade power injector for the MLA-30, but lower noise with the MW transmit antenna on the SDR.
No calibrated carrier measurement at this time, signal peaking to about S4 S6 here, assuming my math is correct.

0235 a mellow piano piece in a minor key.  Too close to the noise for identification.
0239 some kind of ID followed by a new song.  Motown kinda sounding?
0244 a dance version of the new years eve song.  Sounds like Mariah Carey.

Carrier looks to be about 50 Hz off.

Thanks for the show!

+-RH

190
General Radio Discussion / Re: IBOC list
« on: December 18, 2020, 2241 UTC »
Agreed, the data is old.  AFAIK, all the Entercom stations turned theirs off.  Due to the somewhat fluid ownership state, stations seem to drop on and off periodically.  It really doesn't bother me if they run IBOC during the day, but nighttime operation should be revoked, unless you are running MA3 mode (digital only).

+-RH

191
The RF Workbench / Re: Watch out for those cheap components
« on: December 18, 2020, 2230 UTC »
             
                                          How long before fake humans?

A quick survey of the internet and the media should yield many fine examples of such...

+-RH

192
I'll see what I can do.  I had professed to take a vaca, at least until I can afford to go out again.

...and, no, not that I know of.  Although I did recently have a dream that wtww contacted me wanting me to build them an exciter for their continental.

+-RH

193
General Radio Discussion / Re: Keyed Up on 6925 usb
« on: December 08, 2020, 1717 UTC »
Depends on what you consider dangerous.  IF the rig has been modified for all band transmit, and the antenna is sort of matched, no harm done.  If you haven't modified the radio, and its out of band, nothing will happen.  Even if the radio has been modified, and the antenna is not matched, most modern rigs will fold back output power to prevent damage to the PA.

..As to the legality of such, this is a pirate board after all :)

+-RH

194
Software / Re: audio editing software
« on: December 08, 2020, 0525 UTC »
Audacity is a good FREE program. Lots of tools and features. There is better software to buy but expensive, Audacity should be good enough.  Plenty of YouTube tutorial videos.

https://www.audacityteam.org/download/

+1  It can do just about anything Audition can, and is fine for my needs.  Several commercial stations I know of use it as well, as they just could not justify the ongoing costs of Adobe.

+-RH

195
Huh? / Re: Computer Security
« on: December 02, 2020, 1724 UTC »
Yup, got to that kind of extreme, then leave the default passwords in a switch...

+-RH

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