Look at this!

[Space Varmint]

Crap! Man I'm trying to do some sensitive frequency measurements and everything is iffy on my freq. counter I built. My MFJ freq. counter is just not sensitive enough. So I'm wondering why is it so hard to read these signals? They should be just within threshold no problem. Then I just touch the lead to the freq. counter and I got a rock solid 750 KHz. So I turn off my PLL I'm building and it's still there. So I do a search on the internet and find this:

Call Facilities Location Power

United States

KFQD 750 kHz Day ND2 ANCHORAGE AK US 50.0 kW
KFQD 750 kHz Nit ND2 ANCHORAGE AK US 50.0 kW
WSB 750 kHz Unl ND1 ATLANTA GA US 50.0 kW
WTHQ 750 kHz Day NDD BROOKPORT IL US 0.5 kW
WNDZ 750 kHz Day DAD CALUMET CITY IL US 5.0 kW Pattern
WNDZ 750 kHz Day DAD PORTAGE IN US 15.0 kW Pattern
KKNO 750 kHz Day NDD GRETNA LA US 0.25 kW
WBMD 750 kHz Day NDD BALTIMORE MD US 0.73 kW
WRME 750 kHz Day DAN HAMPDEN ME US 50.0 kW
WRME 750 kHz Nit DAN HAMPDEN ME US 10.0 kW Pattern
WARD 750 kHz Day DA2 PETOSKEY MI US 1.0 kW Pattern
WARD 750 kHz Nit DA2 PETOSKEY MI US 0.33 kW Pattern
KBNN 750 kHz Day NDD LEBANON MO US 5.0 kW
KERR 750 kHz Day DAN POLSON MT US 50.0 kW
KERR 750 kHz Nit DAN POLSON MT US 1.0 kW Pattern
WAUG 750 kHz Day NDD NEW HOPE NC US 0.5 kW
KMMJ 750 kHz Unl DA1 GRAND ISLAND NE US 10.5 kW Pattern
KHWG 750 kHz Day ND2 FALLON NV US 7.5 kW
KHWG 750 kHz Day ND2 FALLON NV US 10.0 kW
KHWG 750 kHz Nit ND2 FALLON NV US 0.25 kW
971126AH 750 kHz Day DA2 LANSING NY US 2.5 kW Pattern
971126AH 750 kHz Nit DA2 LANSING NY US 0.72 kW Pattern
KSEO 750 kHz Day NDD DURANT OK US 0.25 kW
KXL 750 kHz Day DA2 PORTLAND OR US 50.0 kW Pattern
KXL 750 kHz Nit DA2 PORTLAND OR US 20.0 kW Pattern
WQOR 750 kHz Day NDD OLYPHANT PA US 1.6 kW
KAMA 750 kHz Day DA2 EL PASO TX US 10.0 kW Pattern
KAMA 750 kHz Nit DA2 EL PASO TX US 1.0 kW Pattern
KOAL 750 kHz Day DAN PRICE UT US 10.0 kW
KOAL 750 kHz Nit DAN PRICE UT US 6.8 kW Pattern
WPDX 750 kHz Day NDD CLARKSBURG WV US 1.0 kW

Turns out that dern radio station is about two miles from here. I've seen it. It's right across the street from the liquor store. The one in bold. Yes I'm in Atlanta, Tucker GA actually. Where the station is. I hope I don't have to turn this room into a Faraday cage.

 

[mneary]

50kW, 2 miles away, is a whole pile of power! I'm 3.3 miles from 50kW, myself. Pretty much I've always been nearer than 5 miles from a 50kW AM station.

You might be able to get enough suppression just by using a coaxial cable to take your readings, with its shield connected to the common (some call it 'ground') of the oscillator. If your frequency to be measured is significantly higher than 750kHz, try taking the measurement through a 10 pF series capacitor.

It's handy to just use a scope probe.

 

[Space Varmint]

50kW, 2 miles away, is a whole pile of power! I'm 3.3 miles from 50kW, myself. Pretty much I've always been nearer than 5 miles from a 50kW AM station.

You might be able to get enough suppression just by using a coaxial cable to take your readings, with its shield connected to the common (some call it 'ground') of the oscillator. If your frequency to be measured is significantly higher than 750kHz, try taking the measurement through a 10 pF series capacitor.

It's handy to just use a scope probe.

Hey thanks for that mneary. I beat you to it on the capacitor, in fact it was already there but never thought of the coax. I got some RG-174U in storage that might just do the trick.

edit: But what about the low impedance? That's the clinker. 50 ohms on those low power signals may just cause them to disappear. Always something.

 

[3v0]

Bad post title.

"Look at this!"

Very bad choice for a title.
It does not give the reader any info regarding the post.

 

[Space Varmint]

"Look at this!"

Very bad choice for a title.
It does not give the reader any info regarding the post.

Yeah I thought about that later. I was in the middle of heated anger when I posted it. Probes and wires and equipment all around me. Good thing no one was here in person. They may have heard a few words I wouldn't dare post...

 

[mneary]

I don't know what the amplitudes of your signals are, but the MFJ should be able to pick up an attenuated signal. If you probe at a node that isn't capacitance sensitive, the small cap in series with 50 ohms shouldn't kill it.

 

[HiTech]

I was in the middle of heated anger when I posted it. Probes and wires and equipment all around me. Good thing no one was here in person. They might snap a photo that I wouldn't dare want posted...

... you mean this one?

**broken link removed**

 

[Space Varmint]

... you mean this one?

**broken link removed**

Hey HiTech! Where you been keepin' your bad self? Yeah that's pretty close.

 

[Space Varmint]

I don't know what the amplitudes of your signals are, but the MFJ should be able to pick up an attenuated signal. If you probe at a node that isn't capacitance sensitive, the small cap in series with 50 ohms shouldn't kill it.

Yeah the cap should help. Your right. I'm talking very small signals. Like 3 volts P-P. Not willing to measure the power at the moment. Time constraints you know.

 

[killivolt]

Update yourself. Join the Crowd

Crap! Man I'm trying to do some sensitive frequency measurements and everything is iffy on my freq. counter I built. Yes I'm in Atlanta, Tucker GA actually. Where the station is. I hope I don't have to turn this room into a Faraday cage.

Get Updated.

kv Just a thought.

Quit being a non-conformist join the crowd.

 

[killivolt]

My gosh it's me.

... you mean this one?

**broken link removed**

Me for the last 3 weeks and still having issue's with my ClearOne xap-800 in one room I have four inputs I think maybe shorted.

kv

 

[Space Varmint]

Get Updated.

kv Just a thought.

Quit being a non-conformist join the crowd.

?????? I think there might be a hidden meaning in there somewhere

 

[Space Varmint]

Hey! I cheated. It works too. I made a portable Faraday cage.

All I did was take a piece of foil and attach it ground and hold it up between me and the radio station and it worked. I read all my frequencies.

 

[vishwanath]

hi to all.
I am sorry if this post is irrelevant to this thread but i really need some help on tracking a transmitter using triangulation principle. i want to try and implement it in as small a scale as possible. is there any way to measure the distance between a transmitter and a receiver with a resolution good enough to implement it in a small scale?.

Is this triangulation method used in sports like football to measure distance covered by a player so on?. if so how can it be done in such small a scale or better smaller than that?.

Can the direction at which the transmitter is, be determined to a good deal?

please help someone..
thanks..

 

[Space Varmint]

hi to all.
I am sorry if this post is irrelevant to this thread but i really need some help on tracking a transmitter using triangulation principle. i want to try and implement it in as small a scale as possible. is there any way to measure the distance between a transmitter and a receiver with a resolution good enough to implement it in a small scale?.

Is this triangulation method used in sports like football to measure distance covered by a player so on?. if so how can it be done in such small a scale or better smaller than that?.

Can the direction at which the transmitter is, be determined to a good deal?

please help someone..
thanks..

Yes, you can use PLL to measure distance in RF. I wrote up a whole paper on this one time that even has the math equations for calculating distance. I'm trying to find it.

Anyway it is based on the same technique developed by MIT using the Kodak sonic detectors. The automatic focus unit uses sound to measure the distance of an object and set the focus accordingly.