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Author Topic: What is a "birdie"  (Read 8551 times)
N0SOY
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Posts: 72




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« on: August 29, 2012, 04:23:44 PM »

I have a MFJ9406 and I was running a receive only test on 6m with a 10m antenna (My 6m had not arrived ) I kept hitting points where there bfo screamed but there was not any voice on it.  I suspected that it was just a weak signal that I could not lock on to but I wonder if anything else was happening. Or if the radio needs a re-alinement.

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NO2A
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Posts: 806




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« Reply #1 on: August 29, 2012, 06:01:03 PM »

Birdies are generated by the rig itself. I doubt an alignment would make any difference. Some rigs have many,others hardly any.
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KM3F
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Posts: 512




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« Reply #2 on: August 29, 2012, 09:58:16 PM »

Two oscillator signals or harmonics mix together within the radio and are detected by the audio detector same as a normal signal would be.
If the sleight difference in frequency or F1 +/- F2 between them is in the audio range, you can hear it.
Good receiver designs place this issue outside the bands your use so you don't hear them.
Good luck.
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KA4POL
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Posts: 2041




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« Reply #3 on: August 30, 2012, 07:45:04 AM »

Besides being a result of mixing frequencies it is also possible to receive harmonics of internal oscillators. You should see what frequencies you are receiving those signals on. It may well be the case you are receiving DSL signals or something similar as well. An alignment will shift those signals at best.
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AA4PB
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Posts: 12913




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« Reply #4 on: August 30, 2012, 08:20:03 AM »

If its a "birdie" then its internally generated and you will still hear it with the antenna disconnected. If it goes away when you disconnect the antenna then its an external signal rather than a "birdie" and it'll have to be eliminated at the source.
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N0SOY
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Posts: 72




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« Reply #5 on: August 30, 2012, 10:33:52 AM »

Here is an update.  Last night I hook up the power and turned on the radio with no antenna.  No bfo activity but when an antenna was hooked up it the bfo activated on 50.125 and various spots.  I suspect that the radio was picking up weak signals that were not audible but the bfo responded.  ( I am not sure what the correct term actually is. )

Best

David
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KA4POL
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Posts: 2041




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« Reply #6 on: August 30, 2012, 10:50:08 AM »

A beat frequency oscillator or BFO is a dedicated oscillator for creating an audio frequency signal from Morse code or an intelligible signal from a SSB carrier.
You were obviously receiving some such carrier from outside. There can be lots of sources in your house or in the neighborhood. I can for example see my DSL signals.
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WB8VLC
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Posts: 124




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« Reply #7 on: August 30, 2012, 11:53:40 AM »

Your lucky you only have one at 50.125 MHz How about a list of products that cause birdies on all of my 6 meter radios from 50.000 to over 53 Mhz.

1.Black and Decker coffee maker.  Fixed by wrapping cord with ferrite chokes.
2.Netgear Router.  Fix: Replaced wall wart power supply with a home brew linear regulator.
3.CFL lamps.  Fix: tossed all CFL's out and purchased a good supply of incandescent bulbs.
4.Cable TV leakage.  Fix: Removed all of the unconnected cutoff cables handging off of the entry panel and terminated all of the connected but unused ones.
5.Electric lawn mower pulse charger.  Fix: a nice old gas mower as a replacement works wonders.
6.Electric Leaf blower charger, (The green people can toss their electric gas replacements in the garbage as far as I'm concerned)  Fix: used the internal battery for another project and I smashed and tossed the electric leaf blower in the garbage. I can honestly say that it was an exhilerating feeling smashing this junk device with a sledge hammer.
7.Neighbors plasma TV. Fix: 6 meter band modified MFJ 1026 nulling box. This device worked so well that I can now hear and work Europe on a small 5 element yagi during those rare band openings.
8.Street light a half block away with faulty photocell that local Power company hasn't fixed yet.  Fix: keep bugging portland electric to fix this wonderfully designed piece of art ( sarcasim).




good luck with your noise

Mike
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W5DQ
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Posts: 1209


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« Reply #8 on: September 07, 2012, 01:53:50 PM »

One under PAR at most fairways  Grin

Seriouslythough, it is an internally generated carrier that is found by the RX circuitry. They can be most annoying if there is one on a freq you want to operate because basically without redesigning the radio, they cannot be removed.

Don't misinterpret a externally generated RFI signal as a birdie. Many RFI signals will disappear when the antenna port is connected to a dummy load. A 'birdie' will not disappear. In fact, it may sound louder due to the loss of background noise compared to when the actual antenna is connected.

Another difference is you like them in golf and hate them in ham radio!!!

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
KA4POL
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Posts: 2041




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« Reply #9 on: September 07, 2012, 09:48:47 PM »

Golf is a game whose aim is to hit a very small ball into an even smaller hole, with weapons singularly ill-designed for the purpose (Winston Churchill)
That's why we stick to ham radio.
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W5DQ
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« Reply #10 on: September 08, 2012, 01:29:58 PM »

Golf is a game whose aim is to hit a very small ball into an even smaller hole, with weapons singularly ill-designed for the purpose (Winston Churchill)
That's why we stick to ham radio.

Golf, like ham radio, is a pursuit to improve one's abilities. Anyone with minimal coordination and enough attempts can put a golf ball in the cup as well make a QSO. The trick to both is to do be able to do it effectively, when you need to, sometimes under adverse conditions.

I always like the statements made by non-golfer's about how silly and archaic the game of golf is. Golf is one of the oldest organized sports known and it takes some perseverance to get to be good at it, just like ham radio. 

I like both although I will admit. I am much better at ham radio operating than I am at golf.  Grin

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
AA4PB
Member

Posts: 12913




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« Reply #11 on: September 08, 2012, 02:56:26 PM »

Is a QRP golfer one who insists on using a short club?
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KA4POL
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Posts: 2041




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« Reply #12 on: September 08, 2012, 11:24:26 PM »

Actually Churchill did play golf in his younger years. He, however, preferred to play polo which suited him better: live opposition, a much bigger ball.
By the way, golf started out from Scotland.
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N0SOY
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Posts: 72




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« Reply #13 on: September 09, 2012, 09:30:54 PM »

Yes the Scotsmen who invented it must have been really wasted and thought it was funny at the time.

Think about it, knock a small ball into a goffer hold with a bent stick.  Add to it put the hole a long way away.
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W5DQ
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Posts: 1209


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« Reply #14 on: September 10, 2012, 08:42:21 AM »

Yes the Scotsmen who invented it must have been really wasted and thought it was funny at the time.

Think about it, knock a small ball into a goffer hold with a bent stick.  Add to it put the hole a long way away.


Nothing that a steady intake of alcohol won't make appear to be easier than it is Smiley

Gene W5DQ
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Gene W5DQ
Ridgecrest, CA - DM15dp
www.radioroom.org
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