What kind of antenna do you have ? If it a fiberglass whip you may or may not have a tuning rod that may be in the tip of the antenna. If you have a metal antenna then you should be able to adjust it . First,get an external SWR meter and attach it to your radio with a 12" section of jumper coax from the radio to the transmitter side of the meter then your antenna coax goes to the other connector. Now loosen the tuning rod using the alan wrench and set screws on the antenna. Next , place the whip or rod to the bottom and bring it 1/4 " then key you radio and check your swr on channel 1/40/and 19. Write down the numbers you get and then readjust and recheck it. Always writing down the results until you are at least a 1.5:1.
SOURCE: radio shack trc-447
According to the service manual for the TRC-447, the only adjustment is for "power" which is #L205. The only other step in the transmitter alignment is for the "S" meter.
On the Cobra, VR4 is AMC, L14,L13,L12 is AM power.
SOURCE: I was wondering what was the range for the
Antenna :
-should be tuned, have good coax with no pinches, whip is centered over highest flat metal surface, no metal beside adjacent to whip, power is wired to battery direct, not to ignition or cigg lighter. whip is wiped clean of corrosion, whip is up, longer is better.
Praire City car-to-car: 15-20 km's
Praire Rural car-to-car: four-thirds over the horizon. Probably 60 km's.
Alot further over water.
Less within trees and mountains/valleys.
Google "Ham radio" & "ducting" "inversion" "skip" "sun-spots"
these refer to a condition where a radio signal getting stuck between the upper and lower atmospheres and travel intact for 1000's of km's (canada to mexico for example)
SOURCE: i have no problems just would like to tune and
RV2 is modulation. turn that up to get full modulation. L9 and L12 is AM power.
SOURCE: tunning the antenna on radio shack cb trc-447
After installing the antenna, follow these steps to adjust the
standing wave ratio(SWR).
1. Turn on the CB.
2. Set S/RF/SWR/CAL to CAL.
3. Key the Mic and rotate SWR CAL so the meter points
to CAL.
4. Unkey Mic.
5. Set S/RF/SWR/CAL to SWR.
6. Key Mic again and note the actual measurement on
the SWR scale. Refer to the following table to interpret
the reading.
1:1 - 1.5 Great
1.5 - 2:1 OK
2:1 - 3:1 Not So Good
Higher than 3.1:1 Terrible
The ideal standing wave ratio (SWR) is 1:1, or a meter
reading of 1 on the SWR meter's top scale. A SWR ratio
of 1.5:1 to 2:1 is excellent for most mobile CB antenna
applications.
Check the SWR on Channel 1 and Channel 40
If the SWR is higher on 1, make the antenna longer
If the SWR is higher on 40, make the antenna shorter
Most antenna's are adjustable. Make small adjustments at a time.
167 views
Usually answered in minutes!
×