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Forummaster
| | Posted on Friday, January 23, 2004 - 12:15 pm: | 
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Mobile Amplifier Installation Tip’s
While there are many different Amplifiers out there that perform in many different ways, this is to be used as a General Guide for Mobile Installations.
The following Tips are to help you to better utilize your Amplifier and allow your Amplifier to perform Better and Last Longer.
Before you Begin
#1 ~ Overdriving Amplifier.
Very Important! Do Not Overdrive the Amplifier.
If the Amplifier calls for 4 Watts Dead Key then start out trying 3 1/2 watts or 3 or 2 1/2 watts.
Driving an Amplifier with less than 2 watts is not recommended
An Amplifier will sound a lot clearer / cleaner with a little less input. As many meters are not the same I would recommend starting at 3 watts Dead Key and proceed from there.
A radio with the Modulation Limiter clipped or modified can cause major damage to the Amplifier form excessive harmonics. Also try and keep your Modulation at 100% or a little less.
#2 ~ Recommended Coax
I recommend using RG8 Type (Rated 2000 Watts) or RG213 (Rated 5000 Watts) Type Coax with Soldered Connection’s.
I do not recommend using any type of Crimp on Connector’s.
Mini 8U carries a Rating of 1000 watts for use with smaller Amplifiers.
I do not recommend using any RG58 or RG59 Coax for Any Amplifier installations.
#3 ~ AirFlow
Your Amplifier will require a good airflow around and over your amplifier for proper cooling & Maximum Performance or you may even add a Fan Kit for the Amplifier.
This is Very Important with larger size Amplifiers.
Without good airflow your Amplifier will have excessive heat build up and shorten the life of your Amplifier & effect the performance of the Amplifier.
#4 ~ Performance
With your SWR properly set at 1.5 or below, and under normal operating condition’s you can expect many years of use from your Amplifier.
Amplifiers can cause interference to other electronic products.
Should you have these problems with interference you can easily install a Low Pass TVI Filter in Line.
Installation
#1 ~ Connecting Amplifier
When adding an Amplifier to your system you will need a good quality coaxial jumper to run between the Radio and your Amplifier.
This can be a 3 or 6-foot jumper, which generally works very well.
You can use any length you choose but I would recommend at least a 3-foot length.
But, please be aware that the length of your jumper can affect your SWR.
#2 ~ Checking SWR.
When adding an Amplifier to your system it is highly recommended that you have a SWR reading of No more than 1.5 across the band, and less is better.
This measurement should be taken inline between your Radio and the Amplifier, with the Amplifier turned OFF.
#3 ~ Connecting Amplifier to Power.
Very Important! Always use heavy enough wire for the Power Lead coming from the Amplifier and connect it directly to the vehicle’s battery.
Red to Positive post on Battery and Ground the Black wire to the Chassis ground as close to the Amplifier as possible.
Always add a Circuit breaker or Fuse of a higher rating than the Amplifier requires as this will protect the wire coming from the battery should a short ever occur.
I strongly recommend that all connections be Soldered or Crimped Very Well and Die-Electric grease applied to prevent oxidation or battery spray.
A ground lead that is too long can cause problems with the Radio, Amplifier or other electronic products in the vehicle.
| Amplifier Size | Recommended Wire to Use | | 20 Watts - 100 Watts | #14 - #12* Gauge Wire | | 100 Watts - 250 Watts | #12 - #10* Gauge Wire | | 250 Watts - 350 Watts | #10 - #8* Gauge Wire | | 400 Watts - 500 Watts | #8 - #6* Gauge Wire | | 500 Watts - 650 Watts | #6 - #4* Gauge Wire | | 650 Watts - 1000 Watts | #4 - #2* Gauge Wire |
* denotes Recommended wire to use.
Respectfully Submitted
Lon
Tech808
Added Note by Tech671 :
I would use the "recommended input) of all amplifiers with a grain of salt. Start with 1/2 of the recommended input into your amplifier.
Using a decent power meter set your radio so the amplifier DOES NOT exceed 1/3 of it's peak power when keying the mike (dead carrier, not speaking). Preferrably set to 1/4 of peak.
EXAMPLE:
Texas Star DX250. Set radio starting at 2w. With amplifier in max power key the mike. The amp should not exceed 80w or about "4" on the amplifier's meter. KL60. Set radio starting at 2w. With amplifier in max power key the mike. The amp should not exceed 20w. In either of these examples, if you exceed that wattage your radio needs to be turned down in power.
Be aware that many amps' peak power ratings are grossly overrated and you need to know a fairly accurate peak power ability of that amplifier to set your radio properly.
EXAMPLE:
KL203, actually a 120w amp. Black Cat 300, actaully a 200w amp, same for the KL400. KL500 actually a 400w amp. KL200p actually a 100w amp. |
Climber
Member
Username: Climber
Post Number: 64
Registered: 1-2003
| | Posted on Tuesday, August 24, 2004 - 7:42 pm: |
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Forummaster & 808
I just read this and need to make a change.
Thanks for reminding me the right way to set up.
Climber |
Cbblackbeard
Intermediate Member
Username: Cbblackbeard
Post Number: 101
Registered: 12-2003
| | Posted on Tuesday, August 24, 2004 - 11:01 pm: |
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Can any damage occur if my radio dead keys 1 1/2 watts instead of 2 watts?
Can I use 10 gauge wire with a Texas Star 250?
I had my Palomar 250 installed by a "professional" and he connected BOTH power and
ground to my vehicle's battery, is this ok? |
Tech808
Moderator
Username: Tech808
Post Number: 3391
Registered: 8-2002
| | Posted on Wednesday, August 25, 2004 - 8:12 am: |
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Cbblackbeard.
Question #1 ~ NO Damage will occur to your radio if use 1 1/2 watts of drive.
Question #2 ~ YES you can use 10 Gauge wire which is what I use on everything Mobile.
Question #3 ~ YES it is OK to connect Both the Positive and Negative direct to the Battery.
Hope this helps,
Lon
Tech808 |
Cbblackbeard
Intermediate Member
Username: Cbblackbeard
Post Number: 102
Registered: 12-2003
| | Posted on Wednesday, August 25, 2004 - 10:07 pm: |
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Thanks Lon !
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Poppathree
Junior Member
Username: Poppathree
Post Number: 38
Registered: 2-2004
| | Posted on Thursday, September 01, 2005 - 3:27 pm: |
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Cbblackbeard,
I agree with Lon, but if you have any interference with your vehicle electronics (noise over stereo, dash equipment,etc.)try hooking the ground wire to the nearest chassis ground. I had all sorts of interference with the ground going to the battery, because the wire can radiate or re-radiate rf. Once I grounded to the chassis (I used the seat mounting bolt),all the RF problems disappeared. |
Moonraker
New member
Username: Moonraker
Post Number: 9
Registered: 3-2005
| | Posted on Monday, September 05, 2005 - 1:13 pm: |
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If i check my swr with my amp on, will i get an accurate reading? Also, is it a good idea to check the swr between the amp and the antenna or is the reading between the radio and amp the only important one? |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1399
Registered: 7-2004
| | Posted on Monday, September 05, 2005 - 5:40 pm: |
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check radio to antenna with NO amp even in line.
then check with amp in line & OFF!
then check inline with amp ON!
you can use 2 meters, 1 between radio & amp, & 1 between amp & antenna.
or just 1 between amp & antenna-that's the 1 you NEED!
meter in radio can pass for 1 between radio & amp.
ALL readings should be well under 1.8:1. even under 1:5.1. with amp on, they may go up, but still should be well under 1.8:1.
when they are only bad with amp ON, check & change jumper to different lengths. if mag mount antenna, move it around. DO NOT run 10' of coax to put meter from amp back to front seat of vehicle. leave it where it is, or get 1 with remote unit. |
Moonraker
Junior Member
Username: Moonraker
Post Number: 10
Registered: 3-2005
| | Posted on Monday, September 05, 2005 - 6:26 pm: |
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Thanks for the info. My swr with the amp off is 1.2:1. With the amp on high, they were almost 3:1. I am using a dual coil antenna and earlier today I put the shorter upper coil where the longer lower coil was and the longer coil where the short one was. The reasoning behind this was that the smaller coil put off less RF and I would not have as much reflected power. I guess this worked. my swr with the amp on high is now 1.6:1.
By the way, my antenna is mounted to the top of the headache rack on my truck and I took the swr reading between the amp and antenna. Maybe this will help someone out there having a similar problem |
Tech808
Moderator
Username: Tech808
Post Number: 6973
Registered: 8-2002
| | Posted on Monday, September 05, 2005 - 6:38 pm: |
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A helpful TIP from Wilson Antenna,
If the SWR is good until power is applied:
The antenna is not the problem. In this case, it is the amplifier. You have already established that the antenna is properly tuned and in good working order with low SWR, except when power is applied. Assume a ham operator is on 10 meters using a solid state amplifier. With the radio only, the SWR is 1.1:1; when the amplifier is turned on, the SWR jumps to 2.0:1. The amplifier is not only transmitting at 28 MHz, but is also transmitting on a second frequency of 56MHz. This is known as a "second harmonic" (2X the fundamental frequency of 28 MHz, transmitting at 56 MHz). Thus the SWR meter is reading both the reflected signal of the normal frequency and the rejected second harmonic signal. The antenna will not accept energy transmitted at 56 MHz, and returns it all back to the radio, which shows up on the meter as high SWR because the meter can not tell the difference between 28 MHz and 56 MHz. In fact, as much as 30% of the power is at 56 MHz. This is generally due to an amplifier that is not adequately filtered. Adding a Low-pass filter at the amplifier output is the only solution. For best results, connect the low pass filter directly to the amplifier using a barrel connector.
Hope this helps,
Lon
Tech808
CEF808
N9OSN
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Moonraker
Junior Member
Username: Moonraker
Post Number: 13
Registered: 3-2005
| | Posted on Monday, September 05, 2005 - 7:58 pm: |
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Thanks for the info, Lon. It all makes perfect sense to me now. |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 1404
Registered: 7-2004
| | Posted on Monday, September 05, 2005 - 8:37 pm: |
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as i've said before, there are times where straight SWR meter will read a 'good' condition, yet a meter measuring reflected power will show a large amount of reflect. at the same time. that is why. whether or not it is the amp causing the problem is open for debate. as moonraker found, making changes in various places can affect what gets reflected. sometimes jumper length, not just radio to amp, but amp to meter, etc, as well as physical placement of antenna. and as in moonrakers case, 'parts' of the antenna. the low pass filter is a trick to use when swr meter shows good, & you get an amp that should do XXX watts, but is showing 35-50% more. hopefully, the filter kills the harmonics, & fwd & ref power gets back to where it should be. THEN, you need to fix the problem... |
Mrhydone
Junior Member
Username: Mrhydone
Post Number: 16
Registered: 7-2005
| | Posted on Thursday, December 08, 2005 - 6:47 pm: |
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DUMB QUESTION:
When checking the SWR do we check it only
with the dead key? (not speaking into mic)
or do we check it also while modulating
(speaking into mic?) |
Hatchet
Member
Username: Hatchet
Post Number: 86
Registered: 7-2004
| | Posted on Friday, December 09, 2005 - 3:57 am: |
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only deadkey, no modulation |
Wolverine
Advanced Member
Username: Wolverine
Post Number: 570
Registered: 2-2003
| | Posted on Friday, December 09, 2005 - 4:20 am: |
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Dead Key (while not speaking into the mike), for an accurate reading.
Wolverine. |
Alsworld
Advanced Member
Username: Alsworld
Post Number: 955
Registered: 1-2002
| | Posted on Friday, December 09, 2005 - 7:54 am: |
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Check it with the Dead Key only.
Alsworld
CEF 101 |
Mrhydone
Junior Member
Username: Mrhydone
Post Number: 17
Registered: 7-2005
| | Posted on Friday, December 09, 2005 - 12:56 pm: |
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thanks!! |
Mrhydone
Junior Member
Username: Mrhydone
Post Number: 19
Registered: 7-2005
| | Posted on Tuesday, March 21, 2006 - 7:04 pm: |
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While checking the swr and i dead key it is
pretty much flat, but when i speak into the
mike the swr goes up to about 1.5 |
Moonraker
Intermediate Member
Username: Moonraker
Post Number: 186
Registered: 3-2005
| | Posted on Tuesday, March 21, 2006 - 10:13 pm: |
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That doesn't matter. Just dead key don't speak into the mic. |
Kid_vicious
Senior Member
Username: Kid_vicious
Post Number: 1333
Registered: 9-2004
| | Posted on Tuesday, March 21, 2006 - 10:53 pm: |
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normal.
you cant trust the movement of the SWR meter to be accurate when modulation is applied.
is simply cant be calibrated in that way.
pay no attention to that meter when talking.
just make sure the PEP wattage stays the same, and you'll know that you are doing fine.
matt |
Patzerozero
Senior Member
Username: Patzerozero
Post Number: 2602
Registered: 7-2004
| | Posted on Wednesday, March 22, 2006 - 3:53 pm: |
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to prove, if you key 10 watts, & swing 50 when talking....
set cal to 10 watt key & view SWR as 1.1:1
then, whistle to 50 watt PEP steady, & you'll see cal needs to be reset. if you do & recheck SWR with 50 watt PEP tone, they'll return to CLOSER to that 1.1:1, rather then showing that 1.5:1 SWR peak. |
Gtr86
New member
Username: Gtr86
Post Number: 5
Registered: 4-2004
| | Posted on Monday, March 24, 2008 - 7:49 pm: |
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Stiffening caps from car audio? Has anyone used a larger cap from a car stereo application on a Larger amp install, will these save your alt or at least give you better wattage? |
Hotwire
Senior Member
Username: Hotwire
Post Number: 2463
Registered: 1-2005
| | Posted on Monday, April 07, 2008 - 1:37 am: |
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My personal opinion I feel they are useless when it comes to rf amps. Caps are made for audio amps so that the bass bumps harder. It's not a constant flow of amps and maintained voltage. Need more watts? Then you got to get the alternator rebuilt.
To be honest it is cheaper to have a standard alternator rebuilt to 200 amps than it is to buy the caps and everything you need to hook them up with.
My fried 100 amp GM alternator cost me 180 dollars to have an upgrade rebuild.
KEEP IT REAL!
Kenny
cef491(27.115lsb)
2sf491(27.555usb)
Indiana
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