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Vulcanrider
New member
Username: Vulcanrider
Post Number: 1
Registered: 12-2005
| | Posted on Saturday, December 24, 2005 - 10:38 pm: | 
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For some reason I am having problems installing a radio in my car...I
know this is a basic procedure and shouldn't be that big of a
deal..but I have tried two different antennas...one cheapy one I got
at walmart and then bought a lil wil..made by wilson. I still get a
high swr reading over 3 on the meter!! The only way I get a good swr
is to run it through my kl-60 amp...then it goes down well below 1 !!
I have andjusted the antennas....tried even switching different
radios, one is a standard uniden 5 watt, the other is uniden but
peaked to 20 pep, neither one seems to make any difference as well
as ...different antennas...etc...but with the amp all of these combos
seem to run a high swr. does the amp make that much of a difference?
oh btw when I turn the amp off I got back to the bad swr...any
suggestions? or ideas? thanks for your help!! |
Dx431
Senior Member
Username: Dx431
Post Number: 1133
Registered: 2-2002
| | Posted on Sunday, December 25, 2005 - 12:09 am: |
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What vehicle is this on and where is the antenna mounted?
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Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 523
Registered: 11-2002
| | Posted on Sunday, December 25, 2005 - 1:27 am: |
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Well, I don't mean to knock to your antenna selection but both are crappy to say the least.
The Lil Will isn't that great of an antenna, it just isn't tall enough to really hear well or transmit power that well either.
I don't know personally what's going on in your set-up. That is weird. Usually SWR readings of 3 or better indicate a short somewhere. I would think the amp would make it worse.
I don't know. Best advice I can give...get it right before you throw the amp in. |
Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 949
Registered: 9-2004
| | Posted on Sunday, December 25, 2005 - 2:58 am: |
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welcome to the forum vulcanrider!
and merry christmas.
you are lucky that i have to work on christmas eve so im on the forum and have some spare time.
OK, my answer is going to seem long winded and way too detailed. just bare with me and we'll get that radio a'workin'!
starting at the beginning; unmount EVERYTHING! dont skip the piece of equipment that you're "sure" isnt the problem.
now, run a length of 8ga. wire from the battery's positive terminal to the mounting location for the radio and amp.
now run a length of 8ga.(minimum) wire from the negative terminal of the battery to the mounting location for the radio and amp.
put a fuse in line with BOTH of these wires.
make sure there is a big cable coming off of the battery's negative terminal that goes directly to the vehicle's body. if your car is old; you should take this cable off, clean it, and put it back on.
now make sure that the radio's bracket makes contact with the vehicle's body through a good metal to metal contact. also make sure that when you mount the radio that a good contact is made from the bracket to the metal chassis of the radio.
splice into the + 8ga. wire with the power wire for the radio.
connect the - 8ga. wire to the black wire for the radio.
the jumper length between the radio and the amp is important in that a high input impedance into the amp will cause most of your power to be reflected back into the radio. (this would show up as a high SWR on the radio's built in SWR meter with the amp inline and on) the reasons are long and complicated, so just trust me here when i say to start with a 12 foot jumper from the radio to the amp. (i know it seems too long and wasted, but it's not)
mount the amp wherever it can be easily reached and gets adequate ventilation.
run the + 8ga. wire to the power wire of the amp.
connect the amp's negative wire directly to the vehicle's body keeping it's length to about one foot.
(always use good quality coax. not from rad shak. if you use their cable, then dont bother taking my advice because you cant count on anyhing working right. use RG-8mini or better, and if you're not a master at putting the PL-259's on, then have someone around who is. these are VERY important and not easy to get on right.)
now that your radio and amp are mounted correctly, lets make sure the antenna is mounted correctly.
since you mentioned a lil wil, and i happen to know that these are good antennas when used properly; we will use it for our examples.
the lil wil is a magnet mount and comes with its own coax.
how does the connector on the end of this coax look? if its corroded or loose; cut it off and put on a good quality PL-259. (not the solderless kind!)
if you must use more cable than came with the antenna; make sure you use a barrel connector and tighten the connection well.
a magnet mount antenna, (well, most mobile antennas for that matter) needs a horizontal ground plane to work properly. even though there is no metal to metal contact between the mag mount and the vehicle body; the mount is "capacitively coupled" to the vehicle body. (you should never remove the plastic from the bottom of a mag mount)
SO! stick that lil wil up on the roof in the center. WHAT!? you cant mount it there? well, we all have to keep the peace with the YL.
if you cant put it on the roof; (you REALLY should) then put in on the center of the trunk.
if you are driving a pickup truck, the antenna needs to be at least a foot away from the cab of the truck if you must mount it on the bed.
if you have a truck box, you can mount it there. (if it's aluminum you can mount a 1X1 foot steel plate on the box and stick the antenna on there)
with the antenna on the roof, (or wherever) connect the coax from the antenna DIRECTLY to the radio if it has a built in SWR meter.
if not, run the antenna coax to the SWR meter and then a short jumper to the radio. (NO AMP INLINE YET!)
turn on the radio, turn the mic gain all the way down, and put the radio on ch. 20.
set the meter to CALIBRATE or CAL, and adjust the reading until it lines up with the calibration mark on the far right side of the meter.
now switch the meter to SWR and key the mic again.
what is the reading?
something you said gives me the impression that you arent reading the meter correctly. it is impossible to have an SWR of "way below one".
SWR stands for "standing wave ratio" and as such, will always be a number compared to "1".
like "my SWR is 1.5 to 1" means that the SWR meter reads 1.5
"my SWR is 3 to 1" means that the SWR meter reads "3" and is probably close to the red zone.
the lowest "theoretical" SWR is 1 to 1. this does not exist in reality.
on this physical plane, the best we can hope for is, 1.1 to 1.
so, lets assume that the reading is 2.0 or less.
this is good! (BTW, if you have a variable dead key; set it for about three watts)
now go to channel 1. set the meter to "CAL" and key the mic. adjust the needle until it sits sqarely on the "CAL" mark on the far right side of the meter. switch teh meter to "SWR" and key the mic.
what is the reading?
lets assume that the reading is 1.5 or less.
now go to ch. 40 and repeat the process, including the recalibration for this channel.
what is the reading?
lets assume that its 2.5 or less.
since the SWR on ch. 1 was lower than the SWR on ch. 40, this means that your antenna is more efficient on the lower freqs. than on the higher freqs. this means that your antenna is too long, and needs to be shortened by about 1/4" at a time until the readings on ch. 1 and ch. 40 are about the same. then check ch. 20. the SWR on this channel should be lower than both 1 and 40.
this is assuming that your antenna works properly.
if after all this remounting and using new cable, (you are using new cable arent you? if you dont have the money or the means to buy good quality cable, then you should wait to do this until you do)
if after all this, you still have an SWR way above three on all channels, and switching antennas does nothing, and switching ALL the cables does nothing, then the radio has a problem. if switching radios has no effect, then your SWR meter is faulty. (i would never buy a used SWR meter)
if the SWR is better than it was, then its time to pu the amp inline. if you have an SWR on ch.20 of 1.5 or less, then hook the 12 foot jumper to the radio and the amp's input. then the antenna coax to an SWR meter and the SWR meter to the amp's output. you should be using a radio with a built in SWR meter if one is available.
put the radio on ch. 20, turn the mic gain down, key the mic, set both the internal SWR meter and the meter on the amps output to CAL, and adjust both meters so that they are in the right spot.
unkey, and set both meters to SWR.
key the mic, what are your readings?
the SWR meter on the amp's output to the antenna should still be 1.5 or very close to it. (if its much higher then you need a new antenna)
the radio's SWR meter should be at 1.5 or less.
if it is higher than this, then cut three feet off of the 12 foot jumper, put on a new connector, and try the whole process over again.
most people find that 8.5 to 9 feet works best.
if not, keep cutting off one foot until you see an SWR of 1.5 or less on the radio's SWR meter.
well, that's about it. are you still with me?
if my advice has nothing to do with your situation, then try to provide as many details on your set up. IE: type of vehicle, type of coax, mounting scheme, etc...
good luck and merry christmas,
matt |
Therealporkchop
Advanced Member
Username: Therealporkchop
Post Number: 525
Registered: 11-2002
| | Posted on Sunday, December 25, 2005 - 11:51 pm: |
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Well said Matt, except I'd figure my antenna coax length and stay with the 12 foot jumper from radio to amp. Nothing will have you chasing SWR like an impedance repeater (incorrect length of coax).
I still think a Lil Will blows though...
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Kid_vicious
Advanced Member
Username: Kid_vicious
Post Number: 953
Registered: 9-2004
| | Posted on Monday, December 26, 2005 - 12:51 am: |
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i agree they're not that great, they should give a decent SWR with a KL60 though.
my dad has one on his truck, and it is coupled to a KL300p, using a 29ltd turned down to 1 watt.
i can hear him from 30 miles away at night with about an S-2.
i used his truck for a road trip one time, and i hated that antenna afterwards.
matt |
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