back swing from amp

[413]

i have tried more than one amp... the palomar 350hd has a back swing as well as the blue thunder.. radio is at a 2 watt dead key and with the amp on im dead keying around 45.. i have tried turning the mic gain down and it still swings backwards.. as well i have checked for voltage drops as well.. any ideas??

radio is at 2 watts and swinging 8

i also read somewhere that the palomar 350hd should be driven with an 8-12 watt dead key.. dose this sound right?? seems really high to me..

[Fluxmaster]

ill let pillpopper chime in on this one

[998]

sounds like high dk to me or bad mod on the radio

[Fluxmaster]

sounds like high dk to me or bad mod on the radio

yea I was gonna say probably something with the radio. Never had anything swing back on me though.

[Pillpopper]

With the amp on your getting a deadkey of 45 watts right? When u modulate whats the metter showing then? What is your SWR's with the box on and off?

[413]

swr's are at 1.2-1.3 dependening on where exactly i check them.. out at the shop or here at the house.. (open versus trees and buildings) ... and they show that both amp on and off...i can key and get a dead key of 45 than it will swing back to about 25... and i have checked with my radio.. 2 watt deadkey swinging 8... figured id make sure of what it was.. i dont trust my built in meter...

[Pillpopper]

Just to make sure, are going by the meter off the radio?

[413]

no... i hate the meter in my radio.. dont find them to be trustworthy.. i checked it with 2 different meters.. both showed the same thing... 2 watt dk with only radio.. 45 with amp on.. and backswing with amp... i checked about some better coax but cant get it here locally.. gonna have to order it..

[Dodgem250]

i also read somewhere that the palomar 350hd should be driven with an 8-12 watt dead key.. dose this sound right?? seems really high to me..

Firstly, if you have a swing kit in the radio... extricate it and reinstall thy jumper wire, put on meter and tune up power...

You read correctly, The HD stand for High Drive, it does require a higher "drive" than a standard amplifier, I would start testing the dead key at about 6 watts and go up from there. I am certainly going to lean towards the radio being the culprit, only because of the lack of input power to the amp, the back swing is a simple result of the lack of signal being sent to the amp.

I am not a big fan of variable power, it has caused more trouble with amps than I care to tell you about, but, in my experience, anyone who uses a HD box, should try the variable power route in the radio...

this is the time you'll ever hear me say, "use variable power"

Thanks,
Dodgem

[413]

i figured it was either in the radio or in my coax.. i wasnt sure if the rg58 was capable of handling power from an amp... as well the radio is not equiped with a swing kit... and this is on a galaxy 959.. so any ideas what needs done exactly??

the 350 hd is going to be put on my galaxy 33... so am i better off setting my high power dk to six and go from there?? and leave low power for barefoot talking??

yall have been alot of help in diagnosing the problem... now i just need to learn what to do exactly to be capable of fixing it...

[Crusher]

If you are using your 959 and using that as the radio to drive amp? Is this correct? I have seen this problem in a few of the Galaxy 225 and 250's. If you are Dking 45 and swinging backwards, you must be using an average or something similar type meter. I have seen many of these mass produced amplifiers were there was never a capaitor across transformer and is mistuned. Something is not right. I have had several that after reworked, would DK 45 and swing 60-70+ watts on a Bird. Sounds like something mistuned in the ouput section.

[Pillpopper]

I would have to agree with Crusher, Sounds like your on a bird or an average reading meter, I would double check this. This does not sound like a radio problem imo. Get back to us on the meter and we will help you trouble shoot.

[413]

i have been using 2 different meters.. one is not set up for pep.. just avg.. the other is a radio shak digital meter that reads pep power... both are showing the same results... if i can ever get everything working correctly im wanting to permanent mount that digital meter in the pickup like it was designed to do...

[Crusher]

It is an amp issue. Something is not right. I am sure someone has already said this, but make sure all electrical connections are tight and secure. I have seen a few installs that were done very cheaply or using undersized or loose or dirty connections. this being said, when you key up and try to to talk you are getting a huge voltage drop. Probably not your case, but figured I would mention it as I have seen this many times before.

[413]

ill recheck everything in my wiring.. i wasnt showing a voltage drop on my fluke 73... but i may pull the cover off and check my voltage internally...

[davemadegangsta]

i figured it was either in the radio or in my coax.. i wasnt sure if the rg58 was capable of handling power from an amp... as well the radio is not equiped with a swing kit... and this is on a galaxy 959.. so any ideas what needs done exactly??

the 350 hd is going to be put on my galaxy 33... so am i better off setting my high power dk to six and go from there?? and leave low power for barefoot talking??

yall have been alot of help in diagnosing the problem... now i just need to learn what to do exactly to be capable of fixing it...

99.99 its the radio......:frown2:

[WorldWideSugarCaneHauler]

Those skip talkers swing their boxes backwards all the times.

[413]

anyone capable of checking and/or fixing this amp.. please pm me.. i will be looking to get my problem straightened out after Christmas is done..

please pm me a price to check it over... than we can go from there...

as well anyone who can do some work to the 959 that is pushing it... i have a spare radio for the time being that i can use in that pickup..

[Stickman]

I don't think it's your amp that is the problem, I beleive it's the radio that is the culprit. What I would do is have everything in line than take 1 of your watt meters and install it behind the radio and see what the radio is doing as an exciter. Just because the radio may show you 2 swinging 8 doesn't mean thats what the radio is seeing when you try to use that radio as an exciter. Also is the vehicle off or is it running? If it's off your battery doesn't have enough power to give the amp. Vehicle should always be running when testing amps. This is because charging systems will but out 14 volts plus the amperage that the amp may need. Most of the guys that do alot of back swinging are using tube amps, as these amps don't tend to loose audio at the higher DK like solid state amps do. What has been done to radio? You may need to have it tune up to give the amp more of a push, or buy a small driver to push it forward.

[Cotton Mouth]

How sure are you that the radio doesn't have a SWING KIT in it? Did you buy the radio new and if so nothing was done to it at the time of purchase, like peak & tune or clip and what ever? Because I have a Cobra 29 Philly that will do that when I use my Digital SWR460 with it but if I put the bird on it everything is normal with forward swing, and from what I can tell that is caused from a swing kit being installed. Never have I had that happen before when I have used the regulated variable power, just the cheap ass swing kits or what ever it is that they call swing kits that everyone seems to be doing to there radios. If you know someone with a Bird you might try it and see and I have heard this happen with other people also and found the same end result. Let us know what you find out though, because I'm curious.

Cotton Mouth.

[ONE37]

Another question would be, what kind of meter are you using? Are you using the cheap DOSY/PARADYNAMIC stuff? Go with a BIRD. More reliable. If you want accuracy? Use an Oscilloscope. Time and voltage read correctly would give you an accurate reading.

When I first started slaughtering radios in the early nineties, everything back swung for me. I didn't know at the time that was not ok. But the golden screwdriver I was learning how to screw radios up from had a beat down 43. Watched the reflect watts on it as much as I could.

Glad I don't do radios no more. No money in it...

ONE37 back out!

[413]

i havnt worked at correcting the problem any recently... and after tearing up the transmission and alot of my electrical yesterday im in no big hurry.. but when i do find the problem i will let everyone know..

[413]

i said i would let everyone know what i found for the cause of my backswing.. it is a voltage problem... dont know exactly how to cure it at the moment... but im dropping close to 1.5-2 volts with it running when i key and modulate... and only starting with less than 14 (according to the volt meter i have installed) dropping to 12 is killing it... im not sure why my volt meter i had inline wasnt showing it... but using my fluke meter that is what i have found... im thinking of a custom built regulator for 15v off the alternator to operate it.. is that a good way to go.. or am i lookn to screw something up...

[zman350]

if thats a digital multimeter it will pick up rf and give u a false reading,and thats wat looks like has happened,if you dropped to 1.5 volt ,your batterry is seriously dead,and your truck would cut off.

[Stickman]

I would drop the dead key on the radio to around 2 watts and let it go. Even tho the amp may say it's a high drive doesn't mean that you will sound all that great, also the lower dead key will not be as bad on the volt. systems as the higher dead key would be. it will still go down on modulation, but not as bad with a lower dead key from the radio.

[Camel221]

Btw I don't think anyone asked this yet but what size wire are you running to the amp?

[413]

zman- ok.. any remondations on a good way to monitor the system?

stickman- this is on a different setup.. not the hi drive.. this on on a blue thunder 200... and i have set the dk down to 2 watt.. is seems to work better when i have it set on 3 on my variable.. (galaxy 959)

camel- this was all rewired with 8ga last week....


guys... i really appreciate the help you have been giving me... learning alot.. im completely new to the amp world on the cb end..

[coolbreeze]

8 ga wire is good for that amp.
what the fuse size
is it to the battery
where and HOW do you have your ground. I hope not a seat bolt un sanded

do the lights dim as you talk?


overall i believe the backswing is from an un tuned or poorly tuned radio.

[Mr. 557]

I agree w/ Stickman and Coolbreeze on this one.
It is general knowledge that inline wattmeters "create" reflect. Most work best with exactly 1/2 wave cable on the input side. First, check the radio and antenna only. Look at the power, both carrier and swing. Check on channel 1, 20 & 40. If it swings backward on any or all of these, then your radio is not properly aligned or your carrier is overdriving the radio (radio does not have maximum peak). If it checks fine there, then hook up to the amp and check it with the amp off. Try different jumper lengths from radio to amp. But more than likely, it is either with the radio itself, wrong jumper length from radio to amp, or wrong jumper from amp to meter. Could even be a combination of those!

[413]

coolbreeze- the amp is fused with a 40 amp breaker about 6 inches from the battery... and is grounded to the dash frame... and that frame has a ground strap directly from the battery as well..(in a different location)..

557... so to figure out my coax length out of the amp i need to just experiment with longer coax correct?? i agree it could be in the radio.. that is more of where i was thinking to begin with.. just wanna be sure before i send it off somewhere...

[Crusher]

Just out of curiousity, how is your radio power leads hooked up?

[413]

ran from an aftermarket fuse panel... all that pannel runs is the cd player.. and the switches for my lights.. and the lights are on a relay.. so the most of the power is to the radio.... and grounded to the firewall..

[Crusher]

I have seen a radio act sick, but normally it was power hook up to radio and huge voltage drop. I had a wire break in the plug this past summer.

[Mr. 557]

Most aftermarket wattmeters perform more accurately with 1/2 wavelength between amp and meter. This limits the change of impedance on the antenna coax.

[Stickman]

In order to get to your 1/2 wave multiple u need to find out your velocity of the coax your using and do the math which is 492 *velocity factor / freq your gonna be on. Hope this helps

[413]

ok... just to make sure i read this right.. it is 492 TIMES (x) vf and divide by freq correct??

would i be better off to set this on channel one or 40.. or right in the middle at 20?? i run about all 40 channels...

[Mr. 557]

Channel 20. Once you get the meter and system set correctly, take the meter out of line and only use it for testing occasionally. The least amount of items in your setup, the better effeciency!

[413]

ok... if i keep using rg58 (been having bad luck with the 8x recently) it says i need 11.9 feet... so is that from amp to antenna.. or radio to antenna.. or is that a complete total between the 2?? or did i completely screw this up.... this is kinda confusing me.. but intriguing at the same time..

[duckkiller127]

i wouldn't run more than a cobra 29 through 58

[coolbreeze]

use 8x in 3,6,9,12,15 ft and see which one works best. some boxes just cant get it all out

[Maniac373]

I smell a SWR vs. coax length controversy starting

MR. ANTENNA THEORY will be here soon...

nothing wrong with agreeing with the input SWR of the amplifier, with varying length coax jumpers--- from radio to driver, and driver to big box-- I have done it myself..

Maniac

[duckkiller127]

i'll be more than happy to debate it, there are facts then theories that people swear by because "this is what happened" but then they don't know WHY it happens that way

[nn216]

Start over get rid of all coax in use and replace with new.Test radio into a dummy load or a known good ant.Check all grounds and other connections,clean all grounding surfaces,check antenna connections,make sure of required clearances.set antenna, with radio only,then install amp in its permanent position,complete with ground t0 frame,install jumper from radio to amp,I use 12ft. or 6ft to start.At this point check for reflect between radio and amp and amp and antenna at low power.if your reflect if any can now be adjusted by slight adjustment of the antenna ,take your time and get it as low as possible.change your jumper from radio to amp to adjust reflect there./after low power adjustment turn on your amp and check reflect,and adjust antenna with all should be good.if not have someone check amp. good luck ps do all your swr reflect test away from any trees buildings,your buddys truck or any other obstructions. NoName216.com

[Mr. 557]

Traditionally, rg58 is more a 75 ohm coax although it was used with cb. If you have an amplifier, scrap the rg58. Use 8x up to 1000-1500 watts. Assuming that your antenna and coax are set properly, your amp is connected and grounded correctly and there are no issues with the radio or amp internally, then you can get an accurate reading with a traditional aftermarket wattmeter by using 1/2 wave coax from the output jack of the amp to the input jack of the meter. This reduces the possibility of changing the impedence of the antenna system. THEN, try different lengths of jumper coax in increments of 3,6,9,12,15,18 BETWEEN the radio and amplifier to match your reflect properly. Just because a Galaxy performs well on 1 length of jumper to the amp DOES NOT MEAN that your Cobra 29 will perform the same on that jumper also. However, with a backward swing, if your antenna and antenna coax are tuned properly, then you will want to use the process of ellimination with the more obvious and easiest to change first (Anything after your final amplifier stage would be considered antenna system. If you have a 1/4 wave antenna and 1/2 wave coax, but use a 3' jumper from amp to external wattmeter, then you are adding 3' + inches to your antenna coax. If you use 1/2 wave instead, then you are less likely to change). Once this is done, then you can change jumper lengths between the radio and amplifier until a match is obtained. With an external meter, this is extremely difficult. If you know what your carrier and SWR are with just the antenna to radio, then you can change lengths with the amp in line until the carrier power and swr are the same with the amp in line as it was out of line. NOW, this is why investing in a BIRD 43 wattmeter will save time and sanity.

[nn216]

rg 58 is 75ohm ......not how is it more 75 than 50. please explain.?????this post is a joke right? ok ok im sorry iget it.

[Stone_Wall_668]

I need a better meter..........

How do I check with a O-scope?

[Mr. 557]

RG 58 and RG59 are common types used in cable tv and sattelite communications. RG6 became the norm because of its better shielding and thicker dilectric, making it more broadbanded and today can still be used in signals to accept most HD broadcasting. RG11 is the best for HD and becoming much more popular, because sattelite broadcast signals are being generated on frequencies beyond the capabilities of some rg6 and heading more that way.
Again, I am not saying that rg58 won't work on cb. Just trying to make it understood that it is not a RELIABLE cable application for anyone planning on using POWER!

[Stone_Wall_668]

Get something ~50 ohms nothings perfect.
And that will handle the pwr out.

Now how do I hook my o-scope to the tx without damaging anything?

[Mr. 557]

Again, there is confusion. RG58 is TECHNICALLY a 50 ohm cable. However I believe there were 2 types. Because of their cababilities of covering frequencies of up to 2,000hz, it was widely used in 75 ohm applications for years. I wasn't trying to start a debate, but rg 58 cable is not a reliable cable to use on a powerfull CB application, therefore a "deterrance" statement was needed for the post, right?

[Stone_Wall_668]

Again, there is confusion. RG58 is TECHNICALLY a 50 ohm cable. However I believe there were 2 types. Because of their cababilities of covering frequencies of up to 2,000hz, it was widely used in 75 ohm applications for years. I wasn't trying to start a debate, but rg 58 cable is not a reliable cable to use on a powerfull CB application, therefore a "deterrance" statement was needed for the post, right?

I agree MR. 557, used it for networks 50 Ohm, and cctv 75 Ohm applications. These are low voltage applications, 1.5V P-P for cctv net 10base-2, I think was 12v

However, I would not use it in my auto for any type of CB installation. Ive seen it melt to the carpet, not that I was running high power :D

Time to start another thread..................sw-668

[BumperJack]

Take it to Stickman just my .02