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antron 99 RG8U SWR
- Thread starter KD2GOE
- Start date
Is the antenna located in a poor location - such as close to power wires or any large metal object?
Is the antenna new; or did you get it used from a Ham guy that trimmed the length for 10m use?
Is the antenna new; or did you get it used from a Ham guy that trimmed the length for 10m use?
@ w5LZ
with what you told me about impedance mismatch with a amp i started looking at breakdown of the circuits of the RCI-2990
I under stand what your saying so I looked at the radio and spread this coil witch I think is part of the trap and it has changed the impedance match, when I spread it dropped the SWR down to a flat 2.0:1 from CH 1 ~ 40
so you are right it is not so much my antenna as it is my radio.
I am new to radios and RF but not new to electronics
here is a pic of the coil.
with what you told me about impedance mismatch with a amp i started looking at breakdown of the circuits of the RCI-2990
I under stand what your saying so I looked at the radio and spread this coil witch I think is part of the trap and it has changed the impedance match, when I spread it dropped the SWR down to a flat 2.0:1 from CH 1 ~ 40
so you are right it is not so much my antenna as it is my radio.
I am new to radios and RF but not new to electronics
here is a pic of the coil.
There can be issues with the radio too. People say that SWR doesn't change as power increases but that is only if everything is working properly. SWR increasing as power increases can happen when there is a problem or problems. One thing that can cause this is bad coax. A problem that may not be as visible at 4W may be much more noticeable at 50W.
Another problem is spurs. If you are producing spurs or harmonics, your SWR will increase with higher power output. This is common problem with export radios. I have recently been reading of spurs being a common ailment of the RCI radios.
Another problem is spurs. If you are producing spurs or harmonics, your SWR will increase with higher power output. This is common problem with export radios. I have recently been reading of spurs being a common ailment of the RCI radios.
That coil is a part of the 54mhz trap circuit. If you disable that trap by spreading the coils, it will leak the 54mhz harmonic into the output. The net result - if it leaking a lot of 54mhz signal - is a higher SWR because the SWR meter is now seeing return current on an antenna that is tuned for 27mhz; not 54mhz. Smoosh it back together.
ok but I have a low pass filter between the radio and the SWR meter blocking any thing over 30mhz before it gets to the meter... and I am getting better SWR with it spread?
i am guessing the spurs is a result of a main bored that is designed to operate in more narrow band like a CB and there pushing it to cover a lot more then it was
ok but I have a low pass filter between the radio and the SWR meter blocking any thing over 30mhz before it gets to the meter... and I am getting better SWR with it spread?
Have you tried it w/o the LPF?
Beginning to think that someone else jimmied with the 54mhz trap circuit.
**EDIT**
Did you get the A99 used or new?
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yes I have, it is an E-bay radio that i am guessing some one molested. so yeah with out a doubt I am Shure some one messed with every thing.
I am talking on it now on 38L with a guy I talked to when I first plugged it in and he told me i have it screaming now the freq is dead on and i sound clear.
here is the internal amp after I worked on it had 2 blown caps 220uf @ 16v volts so I put 2 220uf @ 32v 105c
can some one tell me what the resistor in the far right is for? it had been heated it still had the right value with in 5%..
be for you say some thing it was doing all this before i did this work
also added a fuse to the fan output and to the amp if some thing happens it will blow the fuse and not the psu. and upgraded the 16awg wire to 14awg.. why they put 16awg on the amp and 12 on the main bored ??? I don't know...
can some one tell me what the resistor in the far right is for? it had been heated it still had the right value with in 5%..
be for you say some thing it was doing all this before i did this work
also added a fuse to the fan output and to the amp if some thing happens it will blow the fuse and not the psu. and upgraded the 16awg wire to 14awg.. why they put 16awg on the amp and 12 on the main bored ??? I don't know...
ummm i looked over the hole radio from the back side and it looked like a factory solder job.
can you get a pic of the inside of yours?
this guy has one 2 on his Galaxy Saturn Turbo
http://www.youtube.com/watch?v=c22-aB26cjA
Mkube,
first, you should put that coil back the way it was.
any "improvement" you are noticing is the result of a meter not knowing how to handle the complex impedance.
try this to see what i mean. while the coil is spread like it is, connect your antenna coax to the radio, the other end goes to an SWR meter, and then out of the SWR meter to a known 50 ohm dummy load. (measure the dummy load with an ohmmeter to be sure)
my guess is that you'll see a bit higher than a perfect 1:1 ratio.
either way, you should put it back, because most likely the radio is not the issue, its the antenna.
if anyone else has mentioned this, i missed it.
the antron 99 is a "half wave over a quarter wave mutual transductance tuned antenna".
they say that in the ads. what they dont say is that the "1/4 wave" part is made up of the shield of your coax coming out of the antenna for about the first 9 feet.
this means that if you made a choke balun right at the base of the antenna, you have ruined your counterpoise, hence the high SWR.
try making sure that you have the coax coming straight down from the base of the antenna with no loops or bends in it for the first 9 feet.
after that, you can add a choke balun or route it any way that you need to.
does this sound like something that could be happening at your installation?
LC
first, you should put that coil back the way it was.
any "improvement" you are noticing is the result of a meter not knowing how to handle the complex impedance.
try this to see what i mean. while the coil is spread like it is, connect your antenna coax to the radio, the other end goes to an SWR meter, and then out of the SWR meter to a known 50 ohm dummy load. (measure the dummy load with an ohmmeter to be sure)
my guess is that you'll see a bit higher than a perfect 1:1 ratio.
either way, you should put it back, because most likely the radio is not the issue, its the antenna.
if anyone else has mentioned this, i missed it.
the antron 99 is a "half wave over a quarter wave mutual transductance tuned antenna".
they say that in the ads. what they dont say is that the "1/4 wave" part is made up of the shield of your coax coming out of the antenna for about the first 9 feet.
this means that if you made a choke balun right at the base of the antenna, you have ruined your counterpoise, hence the high SWR.
try making sure that you have the coax coming straight down from the base of the antenna with no loops or bends in it for the first 9 feet.
after that, you can add a choke balun or route it any way that you need to.
does this sound like something that could be happening at your installation?
LC
I put the coil back the way i found it and it didn't change the SWR at all going in to my 50ohm 50 ohm dummy load
one thing to add with the coil spread I am not getting in to my PC speakers...
the coax is coming right down with no kinks or bends the flag pole it is on is all so grounded 3 ways
I am not disputing the fact there is some thing not right with the radio i am going to take it in to a tech this week for a checkup
one thing to add with the coil spread I am not getting in to my PC speakers...
the coax is coming right down with no kinks or bends the flag pole it is on is all so grounded 3 ways
I am not disputing the fact there is some thing not right with the radio i am going to take it in to a tech this week for a checkup
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I am not BSing it stopped coming through my PC speakers after I spread the coil .
I did go back and try to keep the coil together with min spread that would keep out of my speakers and keep my SWR down low.. if that makes every one feel good... radio is still going to the shop to have it looked at.. ill let him know so he knows every thing going on. before that i am going to test it on my friends A99 antenna.
I did go back and try to keep the coil together with min spread that would keep out of my speakers and keep my SWR down low.. if that makes every one feel good... radio is still going to the shop to have it looked at.. ill let him know so he knows every thing going on. before that i am going to test it on my friends A99 antenna.