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Messages - redhat

Pages: 1 ... 85 86 87 88 89 90 91 92 [93] 94 95 96 97 98 99 100 101 ... 107
1381
Equipment / Re: Calibrating S-Meter
« on: January 29, 2014, 1547 UTC »
The only way you'll be able to calibrate it is with a signal generator.

+-RH

1382
+1, even though from what I can remember, it wasn't that good even then.

=-RH

1383
Well, I for one still watch over the air TV.  I don't watch enough TV to justify paying for cable.  Particularly in larger markets with diverse ethnic populations, over the air is still the norm.  You know the old saying "57 channels and there's nothin' on."

+-RH

1384
General Radio Discussion / Re: Shortwave pirate stations
« on: January 27, 2014, 0150 UTC »
As I understand it, most modern era pirates run close to 40M.  This is because it offers a good balance of daytime and nighttime propagation.  It also doesn't hurt that antennas in this range are less unwieldy that the lower bands.  People do operate around 20M as well, but not as many.  USB is probably the most common mode used, AM a close second.

+-RH

1385
Hearing the sign on now.  About S8 with good 5K audio with occasional Peskies on USB.

0029 Radio Ronin ID follwed by Kenny Wayne Sheppard's "Blue On Black"
0041 Instrumental Blues piece followed by RR's "Rock Your Radio" ID
0053 RR "Ionopshere" ID followed by "Howdy Folks, and welcome to DFW"  a reference to "Big Tex" the robotic host of the Texas state fair.
0057 RR ID with email addy.  Signal starting to barber pole a bit, signal also a bit weaker, now down to S7 or so

Other projects are vying for my time, but thanks for the tunes my brother!

+-RH

1386
The Kahn method is how high power shortwave transmitters generate SSB with good efficiency.  I imagine this paper was targeting cell phone PA's to extend battery life.

+-RH

1387
General Radio Discussion / Re: FCC notice of unlicensed operation
« on: January 26, 2014, 2350 UTC »
Based on the number in the report, he was running about 355W ERP.  I personally know a few people who have been busted running far less :)

+-RH

1388
My point was that, series modulation does work, best at low power levels because of the inefficiency involved.  If you were going to do high level PWM ala Harris's MW-5, et all, thats a different story.  High level PWM does work very well, and even today's solid state MW and SW transmitters under 6KW use this principle.  To my knowledge, the only domestic manufacturer of high level tube PWM transmitters is continental electronics.  They have a 50KW "Solid state modulator" which is essentially 48 750V power supplies individually series modulated with PWM and wired in series to get 10KV average B+ for the final tube.  The benefit; no modulator tubes, high efficiency, and lower operation costs.  The custom plate transformer which rolls on railroad track by the way, must be a pricy one.  Never mind the fiber optic drive system.

+-RH

1389
General Radio Discussion / Re: homeland security
« on: January 24, 2014, 0122 UTC »
I'm not sure if they would be trunked or not.  P25 is the norm now.  I worked for a TV station at one point that bought a P25 capable scanner for news purposes.  All the stuff they wanted to hear was encrypted :)  This is also becoming the norm for EMS, fire, and police, at least in the areas I've surveyed.

Good luck,

+-RH


...The 'Old Professor says "Your 9-11 tax dollars at work!"

1390
General Radio Discussion / Re: homeland security
« on: January 23, 2014, 0805 UTC »
My guess is your location will likely influence your likelyhood of hearing something.  I would guess that anything they use will be APCO-25 with some form of encryption.

+-RH

1391
One other thing I forgot to mention, there are a lot of people out there that never report anything.  Even if you give out an email or postal address, I think a lot of people just grin, listen to the music, and move on.  Only the diehards send in reports and such.  The fact that I could be on the air, and call up my cousin several states away and say "go to you car and tell me what you got on 1710" has some merit.

+-RH

1392
I just like the idea that a broader audience could be had by using frequencies that the average American (An important distinction, as the rest of the world stops at 1610KHz.) could hear.  Sometime toward the end of the year we may be doing some MW testing.  That's the goal anyway, lots of hurdles to overcome.  The number of radios that get 1710 is getting smaller and smaller.  Both of my Kenwood car stereos stop at 1700, and most Chrysler radios do too.  I think the GM Delco's go to 1710, as do Carver TX-11a's, and a variety of Walkmans, component tuners, and bookshelf systems at my disposal.

More stereo for your radio ;)

+-RH

1393
I'm not sure I would want to witness the initial startup of a series modulated 10KW AM rig.  Sounds like a fire department affair.

+-RH

1394
Finding a modulation transformer at that power level won't be easy.  I've contemplated similar arrangements with big tetrodes for carrier levels over 10KW, but for the previously mentioned difficulty, decided the best route would be a linear amplifier, rather than high level modulation.

+-RH

1395
This puts medium wave operators in a quandary;  Do we abandon 1710 (and all the casual listeners that might stumble upon MW pirates) in favor of 1720, which cannot be received on any domestic AM receivers?  Or do we use both?

Questions, questions....

+-RH

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