LOW SWR LOW OUTPUT HIGH SWR HIGH OUTPUT

[wavrider]

So the higher the VSWR the more reflected power??

And according to Walt Maxwell "Reflections" the power reflected back due to a mis match of impedance at the antenna will then in turn be reflected at the transmitter and be "IN PHASE" with the transmitted power thus giving the watt meter a higher voltage which will make the meter display a higher wattage output, but this is not accurate due to the reflected power being in phase with the transmitted power.

Here we go again

The best advice i have seen is wrap an rf choke at the feed point and then see what happens.

IF you still want lower vswr readings then adjust the rings to have the meter read what you want it to read.

From the factory they should be set and no adjustment required.

This is not always true and some may need adjusting. Always a chance you got one not adjusted correctly at the factory.it happens.

The readings you posted is very use able .

And as CK posted it may be the radio itself needed alignment.

Don't sweat the small stuff get on the air and make some contacts, have fun.

 

[fourstringburn]

And according to Walt Maxwell "Reflections" the power reflected back due to a mis match of impedance at the antenna will then in turn be reflected at the transmitter and be "IN PHASE" with the transmitted power thus giving the watt meter a higher voltage which will make the meter display a higher wattage output, but this is not accurate due to the reflected power being in phase with the transmitted power.

This is basically what I said in the beginning about reflected power and why you should check SWR readings at a higher transmitter power of more than 10 watts so you can check he reflected power which should be subtracted from the forward power. At low power, the values are too small to really be accurate.

With a high SWR, it usually does make the forward power higher just as your quote says but after you subtract reflected power, than it should be within tolerance of being accurate.This is why most of us that use in line meters use cross meters so we see both reflected and forward power at one glance.

Any fluctuations after checking with a higher transmitter power, then what others have posted about common mode and radio alignments may apply.

 

[Beetle]

ok then, .....could please 'splain to me how you can have a VSWR ratio of less than 1:1?

Yes you can have a less than 1:1 match because 1:0 is perfectly flat or didn't you read that on ham universe.com?

Here is a pic which does show a mobile antenna with a near perfect match with a SWR below 1:1. This doesn't mean the antenna doesn't have other losses which it does in the coil inductance used to match the 50 ohm feedline since the antenna is shorter than a 1/4 wavelength for the given frequency.

What it is showing the resistive impedance (R) is equal to the magnitude of impedance (Z) giving a reactance value (X) of less than 0 in this case.

This shows that the antenna is of good design in regards to the coil loading to match a 50 ohm load ( really 52 ohms) and I have mounted the antenna with a good and solid D.C. ground.

Since this antenna is nearly 7 ft. tall, less inductance coiling is used to match it to 50 ohms therefore less losses from the loading coil which results in a better ERP ( effective radiating power) when compared against a 4 or 5 ft. coil loaded mobile antenna.

My previous Hustler RM series I replaced with the same mount on the same vehicle didn't give near as good as a reading as this antenna did.

For those interested, this analyzer reading is from a Sirio 5000 performer series 3/8 mobile mirror mount antenna.

[/QUOTE]
The SWR shown in the picture is 1.04:1. It's not "less than 1:1" because a ratio, by definition, is a comparison of a value with unity, or 1.

The reactance shown in the picture is slightly capacitive as shown by the minus sign in "X: -0.6Ω". The absolute value of reactance can't be less than zero.

Nor is 1:0 a valid ratio.

 

[fourstringburn]

Yes you can have a 1.0 SWR or below 1.1 as shown. I get what your saying by mathematical definition though.

The reactance value is in the negative so what should it be called then?

Aren't all shortened mobile antennas capacitive in nature? The analyzer pic also gives the measured capacitive value.

See post 15 and click link for a SWR table showing power loss.

 

[Captain Kilowatt]

Yes you can have a 1.0 SWR or below 1.1 as shown. I get what your saying by mathematical definition though.

The reactance value is in the negative so what should it be called then?

Aren't all shortened mobile antennas capacitive in nature? The analyzer pic also gives the measured capacitive value.

See post 15 and click link for a SWR table showing power loss.

Yes you can have an SWR of 1.0 HOWEVER you cannot have an SWR ratio of less than 1:1. It is an impossibility. People have to be careful when expressing SWR as either a definite number value such as 1.8 (which implies 1.8 to 1 since it is a ratio) or expressed as 1.8:1

 

[fourstringburn]

Yes you can have an SWR of 1.0 HOWEVER you cannot have an SWR ratio of less than 1:1. It is an impossibility. People have to be careful when expressing SWR as either a definite number value such as 1.8 (which implies 1.8 to 1 since it is a ratio) or expressed as 1.8:1

Thanks for clarifying!

 

[Stellasstillarat]

This sounds like a good starting point. He doesn't own a dummy load but I own one of those cheapo cylinder shaped one with all the fins on it. I think it rated at 20 watts 60 pep. If this is good enough for a stock output radio I will be glad to lend it to him. Are they any good? I purchased it and never used it. Still in the package. O think it's a radio shack.

Another thing is to try the radio into a dummy load and check the power output on ch. 1 and 40. It is possible the radio needs a slight alignment and the power is not even across the band.

 

[Stellasstillarat]

It's funny you mentioned the choke. I used the link a member listed about that below the feed point eight 8" rapped coaxial choke. I found it interesting and was actually gonna suggest he'd do that but didn't want to advise him to do something that may not help his situation. As I mentioned he doesn't seem to be hurting his rig but it seems to be bothering him as he didn't expect to have to begin adjusting the a99's rings as it's advertised to pre tuned for mid band but he wants to get it correct before he purchase an amp and runs it on that setup. He doesn't have access to this information. I will copy all replyes and let him sort them out himself. So far all are great suggestions. Thanks

So the higher the VSWR the more reflected power??

And according to Walt Maxwell "Reflections" the power reflected back due to a mis match of impedance at the antenna will then in turn be reflected at the transmitter and be "IN PHASE" with the transmitted power thus giving the watt meter a higher voltage which will make the meter display a higher wattage output, but this is not accurate due to the reflected power being in phase with the transmitted power.

Here we go again

The best advice i have seen is wrap an rf choke at the feed point and then see what happens.

IF you still want lower vswr readings then adjust the rings to have the meter read what you want it to read.

From the factory they should be set and no adjustment required.

This is not always true and some may need adjusting. Always a chance you got one not adjusted correctly at the factory.it happens.

The readings you posted is very use able .

And as CK posted it may be the radio itself needed alignment.

Don't sweat the small stuff get on the air and make some contacts, have fun.

 

[Beetle]

Yes you can have a 1.0 SWR or below 1.1 as shown. I get what your saying by mathematical definition though.

The reactance value is in the negative so what should it be called then?

Aren't all shortened mobile antennas capacitive in nature? The analyzer pic also gives the measured capacitive value.

See post 15 and click link for a SWR table showing power loss.

That "measured capacitive value" is, I believe, the total capacitance downstream from where the analyzer is connected. This includes feedline and connectors.

A reactance with a negative value is capacitive; with a positive value, it's inductive. It's NEVER "zero".

Yes, shortened antennas tend to be capacitive; that's why there's a matching system provided which is made up of values of capacitance AND INDUCTANCE to cancel the mismatch. The display of the analyzer indicates the antenna in question is a very small bit too short: negative value = capacitive. Common sense suggests that it's close enough for any applications you're likely to run into in amateur radio.

 

[Captain Kilowatt]

This sounds like a good starting point. He doesn't own a dummy load but I own one of those cheapo cylinder shaped one with all the fins on it. I think it rated at 20 watts 60 pep. If this is good enough for a stock output radio I will be glad to lend it to him. Are they any good? I purchased it and never used it. Still in the package. O think it's a radio shack.

It's fine for this.

 

[Stellasstillarat]

the OP and his buddy are both complete newbies,......and he stated that,...............

do you think he understood anything you posted?

I absolutely understood all the "how to fix it" answers to my op.
. Even you can get schooled I guess.
1.1 not possible huh?
I think this is where you go back and forth with the person who posted 1.1 is possible.
Break out the books drainbamage. I'm sure you'll try your best to dispute that clame.
I actually missed the :1 when I posted 1.1.
It should've been 1.1:1 but didn't think correcting it would changed the fix it answers as it wouldnt have changed the facts stated in my op. Swr and output rise as he goes up in frequency.
So I left it alone.