Messages

976

The RF Workbench / Re: Modulated 5W NS40

« on: September 02, 2016, 2152 UTC »

...A lightbulb just went off.  Have him check and see if the output stage in his dead amp is BTL (bridge transformerless)  If so, shorting the negative output to ground could destroy half the output stage in the amplifier.  BTL is becoming more popular because for the same supply voltage and speaker impedance, it allows four time the audio power (double the voltage swing).

The source impedance of the amplifier is generally unimportant, and under normal circumstances shouldn't bother the amp.

+-RH

977

The RF Workbench / Re: Modulated 5W NS40

« on: September 02, 2016, 2106 UTC »

Either the inductance of the 'modulation choke' wasn't sufficient to keep the audio out of the power supply bypass circuity, or the turn on surge made its way into the amp and killed it.  My bet is on the former, because if the input impedance is too low, the amp won't be happy.  Its also possible that there is a shorted turn in the winding of the choke he's trying to use, and that will severely lower the drive impedance too.

+-RH

978

Huh? / Re: The state of US media today...

« on: August 31, 2016, 2131 UTC »

Funny, I got the same email the other day.  It would be nice if the media focused on telling the news, instead of pushing narratives and running all this human interest manure.  Most of the 'trending' stories I've seen lately are all celeb gossip.

Sigh...grunt...

+-RH

979

General Radio Discussion / Re: 40 m dead carrier curiosity

« on: August 31, 2016, 0441 UTC »

Could be a birdie in the receiver itself.  Sometimes funny things happen to rigs when they get transported.  Unless you heard it on another radio, that would be my guess.

+-RH

980

General Radio Discussion / Re: Man Stung With $15,000 Fine in North Miami Pirate Case

« on: August 30, 2016, 2248 UTC »

Ya know, you could add a highpass filter to your setup to eliminate most of your issues with MW...

http://www.qsl.net/kp4md/mwfilter.htm

http://www.dxing.com/tnotes/tnote06.pdf

+-RH

981

Huh? / Re: The DXers' Candidate

« on: August 29, 2016, 1714 UTC »

Yeah, but my plasma TV works for less than your plasma tv....

+-RH

982

General Radio Discussion / Re: Man Stung With $15,000 Fine in North Miami Pirate Case

« on: August 29, 2016, 0438 UTC »

Yet another reason I cringe when I hear someone is broadcasting with a transmitter they built with no real test equipment, or bought from China on Ebay.  Just because the meter moves does not mean all is well, and that is one of reasons for the type acceptance rules from the three letter company.  Commercial stations are supposed to perform NRSC measurements for occupied bandwidth on BOTH AM and FM stations any time something in the transmission system is changed, and are required annually on AM's.  Even in the commercial world equipment fails, and sometimes you won't notice until the station fails its NRSC annual.

+-RH

983

General Radio Discussion / Re: No amateur station shall transmit music

« on: August 28, 2016, 1925 UTC »

Perhaps he has a big splinter?  Ahhhh...

"He's going to be very popular..."

+-RH

984

FM DX Loggings / Re: What is the farthest station heard

« on: August 26, 2016, 2031 UTC »

There was a DX'er by the name of Bruce Elving near Duluth, MN who was rumored to have heard commercial FM stations from Germany.

+-RH

985

Huh? / Re: Does dropping malicious USB sticks really work? Yes, worryingly well…

« on: August 09, 2016, 0010 UTC »

The old trick I was told was to leave a thumbdrive in the elevator with 'HR Files' written on it.  Apparently curiosity does indeed kill the cat

+-RH

986

General Radio Discussion / Re: GPS Under Attack as Crooks, Rogue Workers Wage Electronic War

« on: August 08, 2016, 1749 UTC »

On an unrelated note, has anyone else noted the amount of EMI trash that gets thrown from modern semi tractor trucks?  I had instances where AM is unusable for several hundred feet around the vehicle.  Inverters or APU's perhaps?

+-RH

987

General Radio Discussion / Re: AM Pirate Loggings

« on: August 05, 2016, 0737 UTC »

I am aware of the verbiage you speak....lol

+-RH

988

General Radio Discussion / Re: Surprises of the Faraday Cage

« on: August 03, 2016, 1747 UTC »

Just thought of this, I wonder if skin effect is partially responsible for the lack of shielding by skinny conductors.  Following this logic, you may be able to get away with chicken wire at MW frequencies, but not above 50 MHz or so.

Just a thought...

+-RH

989

General Radio Discussion / Re: AM Pirate Loggings

« on: August 03, 2016, 1744 UTC »

Either way, glad to see the new forum.  It will be interesting to see whether DX'ers categorize 1720 KHz as MW or SW 

+-RH

990

QSLs Received / Re: XFM QSL Card !!!!

« on: August 02, 2016, 0648 UTC »

Last I checked, part 97 only seems to care about TPO, so if you can build it, have at it   After all who couldn't use another 17dB...

+-RH