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Message |
    
Freebird
Intermediate Member
Username: Freebird
Post Number: 397
Registered: 1-2003
| | Posted on Thursday, March 23, 2006 - 12:58 am: | 
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my radio is getting backwards swing on AM.what is the cause of this?and how do i fix it?thanks |
Wolverine
Advanced Member
Username: Wolverine
Post Number: 613
Registered: 2-2003
| | Posted on Thursday, March 23, 2006 - 5:38 am: |
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You are overdriving your amp, which increases heat and distortion like muffled and pinched modulation. Lower your radio's dead key to 2 or 3 watts.
Wolverine. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1341
Registered: 9-2004
| | Posted on Thursday, March 23, 2006 - 10:21 pm: |
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if it is causing the meter needle on the radio to kick backwards when modulation is applied, then you have exceeded the transmitters power output capacity.
the radio will "try" to put out the watts you are asking of it, but when you talk, there is no room left to go up, and the circuit is designed to reduce power when this happens. that is your back swing.
to remedy this: first make sure you are not trying to run the AM power pot at max.
remember doubling your output power will only gain you 1/2 an S-unit, so trying to get an extra 2-3 watts from your 4 watt radiois isnt going to be noticed on the other end.
if the radio is a single final radio, then the dead key should be no more than about 4-5 watts. this will leave enough room for the radio to swing up to its PEP wattage.
if its a dual final radio, deadkey should be 8-10 watts.
now, you may have just done a "tune up" on the TX coils, and thats when you noticed the problem.
you probably tuned the cans with a dead key. sorry, that wont work too well. you have to say, "ahhhh" into the mic in an even tone while tuning the cans. that way they are peaked for voice peaks, not dead key.
sometimes its hard to max out the coils with your voice because it fluctuates too much causing the needle to be erratic.
a cheap and dirty trick is to cause your mic to squeal, and use this for the voice modulation.
its not the best thing though, as that tone is not a good representation of your voice.
if you are spreading or compressing any of the coils in the radio, PUT THEM BACK THE WAY THEY WERE! sure, it shows a couple of watts on the ol' wattmeter, but those watts are not on the channel you are transmitting on, and they are only causing TVI and splatter and are not helping you get heard. the wattmeter cannot tell the difference.
so what kind of radio is this anyhow?
matt |
Freebird
Intermediate Member
Username: Freebird
Post Number: 399
Registered: 1-2003
| | Posted on Saturday, March 25, 2006 - 11:17 pm: |
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thanks for the info |
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