| Author |
Message |
    
Ncrebel
| | Posted on Thursday, April 18, 2002 - 9:46 am: | 
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Hey,I have a Maxon MCB45 with the high and low conversion in it that I just got yesterday.WEll,I was checkin the SWR on it and the SWR is fine on the regular 40 am channels and on the high channels,but when I switch to low channels my SWR wants to go a little high.Its not putting me in the red or anything like that it just sends my SWR up to like a 2 or something like that.Once I go to low channels 30-40 though it starts going back down.Any thoughts?By the way I have a A99 hooked to that radio.Thanks |
bruce
| | Posted on Thursday, April 18, 2002 - 10:33 pm: |
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its tuned to about 27.3 you need to retune it to 27.0 but risk VSWR going high on your high channles |
Tech181
| | Posted on Friday, April 19, 2002 - 12:12 am: |
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Ncrebel,
What you got to do is ask yourself, what frequency will be the highest I will most likely talk on regularly and what frequency will be the lowes I will talk on most regularly. Then find the middle.
For an example I will use my setup. The lowest I go is 26.895 and the highest is usually 27.555. Add those two freqs together and then divide them by "2". You get 27.225. That's where you set it.
Once you find the middle you can adjust for optimum SWR there and then your standing wave will be the same at the top and bottom frequencies.
I have found that A-99's are usually better on the higher end than the lower out of the box, even though they claim to be tuned for the middle of the CB band.
Steve
Tech181
Tech181@copperelectronics.com |
Ncrebel
| | Posted on Friday, April 19, 2002 - 2:40 pm: |
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Okay,thanks guys,well,I have a stupid question kinda,how do you tune the antron for SWR?It's got like a ring at the bottom of it kinda like a nut that you can turn,is that how you tune it?Thanks for your help.Oh by the way....anybody know where I can get a frequency chart off the net that I could print out or something?thanks |
Taz
| | Posted on Friday, April 19, 2002 - 5:59 pm: |
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Yes, tune the antron with the rings. |
707
| | Posted on Friday, April 19, 2002 - 8:09 pm: |
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Here's a little trick I learned...
You can "flatten" the SWR a bit by taking a piece of thin aluminum wire, about 4 inches long, wrap 3 or 4 turns tightly around the radiator, just flush with the antenna base, leaving the excess sticking straight out from the radiator. Then cut off all but about 2 inches, leaving it sticking straight out. Now, check SWR, and clip off the wire about 1/8 inch at a time until you get a good match on CH1. Then, check ch40. If it is high, curl the wire down towards the base very slightly and check again. Continue this process until you get a suitable match across the band.
Also, instead of wrapping the wire around the radiating element, you may unscrew it from the base enough to get one wrap around the threaded part, then tighten back down. |
bruce
| | Posted on Friday, April 19, 2002 - 9:34 pm: |
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here is something intresting on the a-99 a plot of e/h plane
http://diana.bib.uniurb.it/antron/antron.htm
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