| Author |
Message |
    
Skilletlicker
| | Posted on Sunday, November 16, 2003 - 2:58 pm: | 
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i have asked this question about three times butcant get an answer:on how do i adjust the recieve on my 19-290 midland i know where the adjustements are but unsure if i can use a volt meter or what ,i set the wattage and the modulation and a power mic on and it sounds great almost as good as my galaxy
thanks
the skilletlicker |
Ss8541
| | Posted on Sunday, November 16, 2003 - 11:52 pm: |
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there is no way to properly adjust the rx on -ANY- radio without some type of rf generator. sorry. |
Skilletlicker
| | Posted on Monday, November 17, 2003 - 4:45 am: |
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thanks Ss8541 for the information
skilletlicker |
bdonovan
| | Posted on Friday, November 28, 2003 - 8:41 pm: |
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What about the use of an other cb keyed on same freq at a few hundred feet away?
? |
2600
| | Posted on Friday, November 28, 2003 - 10:48 pm: |
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I have seen plans for home-made attenuators. Meant to allow using a CB transmitter as a signal source for receiver alignment. Basically it's a dummy load that taps off only a tiny portion of the radio power to feed into a receiver. My experience is that this only works with the radio's cover in place. Once you take off the metal covers, the receiver will pick up the stray RF energer that escapes from the dummy load into the room. I remember one of them that used a fifty-foot piece of skinny RG-58 coax as part of the setup. I think they called it a "five-mile simulator". Trouble is, five miles isn't far enough. Aligning a receiver for max sensitivity means turning down your steady "test" signal low enough that you CAN'T hear it any longer. Unless the test signal is down at the bottom of the S-meter, the "peaks" you look for on the tuning slugs will will be close, but not really right.
Years ago I thought I could get away with using a cheap Heathkit RF generator, by adding shielding and filtering to it. With all my effort, the weakest signal I could make it turn down to was between 2 and 3 microVolts. Way too much. I got by with it until I could snag one with a real attenuator. One with output level markings on it.
Getting a receiver "peaked" properly may not really require a big, expensive signal generator, but troubleshooting a defective receiver is another story. If you can't tell how much you are pumping into a receiver, there is no way to judge how sensitive it is. Or isn't.
The old-timers' way of judging receiver sensitivity is to unplug the antenna, and then plug it back in. If the noise level from the antenna flickers the S-meter needle, it's as sensitive as you can use. Can't hear anything weaker than the noise, after all. If you CAN'T tell whether or not the antenna is plugged in by comparing noise level, that receiver is not sensitive enough. If it can't hear that noise level, there will be other things it can't, but should hear.
73 |
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