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Correct Place to Test SWR?
- Thread starter Riverman
- Start date
Sorry, I was contemplating tonight's Chili recipies'...spice spec sheet...
I actually had several questions I'd like to know; but looking over this I realize thus; to ask you for more answers would be a punishment that would even have changed the disposition of such hard hearted individuals - that even Karl Marx would have decided to become a Patriot...
My only question would be, the length of coax in between these sections.
Why?
Well I got chided for using the terms used here - in a discussion about Coax Connectors like the words "Impedance Bumps" - and yet in this scenario - unless others correctly identify your "impostor" in the lineup...? I can't help but wonder if this very "impostor" is that creature...
The devil in the details; it's the smaller, subtle changes to the coax levels of impedance across these points, Read: using so many "insertion points" and the problems each connection has added to the inherited losses versus straight "waveguide" that others say to use Coax inhindered (Read:Non-Chopped/Diced) and leave the mess outside when things get windy...
Meaning why cut up a good cow when you can grind the local deer population into Venison hamburger for your next batch of Homemade non-Hormel - based chili?
Ok, perhaps I've got cooking on my mind but then when it comes the cookouts. why not fire up the Grill, or your amp ( accomplishing pretty much the same thing) only while on one, you invited the friends from your Neighborhood, while the other is inviting them from several states away...
And depending on how the coax is feeling as far as being irradiant - maybe those snob nosed neighbors from church might ask you to work on this Sundays Sermon to help out the Pastor since they can't avoid your invitation for free food thru their (Confused) Alexa, just remember to announce (thru the use of your amp) that if possible - bring a dish to pass.
Ok, looking over the "numbers" I see more of the R values as having repetition meaning the ideal ohmic values are still there and not varying by much. The "inversion" confustion comes from this chart...
Note the Green Arrows pointing to two readings of special note...
How far away in Coax length, are these two readings taken?
(Not just physical distance - the length of Coax between them)
The above it why I really didn't want to point any fingers or make any observations but I cannot be Schrodinger's Cat and wonder why the Vial hasn't gone off yet...
O-Umlaut or Diaeresis - Form whom shall the Cat Purr?
I only ask because you have now queried twice over this event and like the animals that keep coming back to the Back Porch doorstep for more food - so then it is I that which must, then, ask of you...
Call me the Bully in this scenario...
What is your main worry?
The PEP - may simply be a reflection of the tuning tank and output network "trimming" of the 52-MHz trap or 2-nd harmonic attenuation Pi-Filter stuff that is making your PEP values seem to fall like a rock closer you arrive the ends (higher channels in this instance) of this CB band...
The main concern here is are you causing any interference? IF so, then this may indicate you have a Pi-Filter element off spec, meaning the "trap" is working further back towards the 27MHz./ not at 52 MHz where it would originally reside.
Or...
The coax itself may be playing "Maxwell" and showing you that one of your supposed 50-ohm connections is more like a 75-ohm and now you have a Balun (By Device or By Connector) - albeit a longer one than most are used to working with...
I actually had several questions I'd like to know; but looking over this I realize thus; to ask you for more answers would be a punishment that would even have changed the disposition of such hard hearted individuals - that even Karl Marx would have decided to become a Patriot...
My only question would be, the length of coax in between these sections.
Why?
Well I got chided for using the terms used here - in a discussion about Coax Connectors like the words "Impedance Bumps" - and yet in this scenario - unless others correctly identify your "impostor" in the lineup...? I can't help but wonder if this very "impostor" is that creature...
The devil in the details; it's the smaller, subtle changes to the coax levels of impedance across these points, Read: using so many "insertion points" and the problems each connection has added to the inherited losses versus straight "waveguide" that others say to use Coax inhindered (Read:Non-Chopped/Diced) and leave the mess outside when things get windy...
Meaning why cut up a good cow when you can grind the local deer population into Venison hamburger for your next batch of Homemade non-Hormel - based chili?
Ok, perhaps I've got cooking on my mind but then when it comes the cookouts. why not fire up the Grill, or your amp ( accomplishing pretty much the same thing) only while on one, you invited the friends from your Neighborhood, while the other is inviting them from several states away...
And depending on how the coax is feeling as far as being irradiant - maybe those snob nosed neighbors from church might ask you to work on this Sundays Sermon to help out the Pastor since they can't avoid your invitation for free food thru their (Confused) Alexa, just remember to announce (thru the use of your amp) that if possible - bring a dish to pass.
Ok, looking over the "numbers" I see more of the R values as having repetition meaning the ideal ohmic values are still there and not varying by much. The "inversion" confustion comes from this chart...
Note the Green Arrows pointing to two readings of special note...
How far away in Coax length, are these two readings taken?
(Not just physical distance - the length of Coax between them)
The above it why I really didn't want to point any fingers or make any observations but I cannot be Schrodinger's Cat and wonder why the Vial hasn't gone off yet...
O-Umlaut or Diaeresis - Form whom shall the Cat Purr?
I only ask because you have now queried twice over this event and like the animals that keep coming back to the Back Porch doorstep for more food - so then it is I that which must, then, ask of you...
Call me the Bully in this scenario...
What is your main worry?
The PEP - may simply be a reflection of the tuning tank and output network "trimming" of the 52-MHz trap or 2-nd harmonic attenuation Pi-Filter stuff that is making your PEP values seem to fall like a rock closer you arrive the ends (higher channels in this instance) of this CB band...
The main concern here is are you causing any interference? IF so, then this may indicate you have a Pi-Filter element off spec, meaning the "trap" is working further back towards the 27MHz./ not at 52 MHz where it would originally reside.
Or...
The coax itself may be playing "Maxwell" and showing you that one of your supposed 50-ohm connections is more like a 75-ohm and now you have a Balun (By Device or By Connector) - albeit a longer one than most are used to working with...
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Te distance between the readings at the Antenna and the Amp is 90'.
87' RG8x from antenna to SWR Meter and a 3' RG8X jumper from Meter to Amp.
That said, I really am not concerned. No interference and all is working great. Just one of those who obsesses over numbers. Have already fallen off the wagon and forgotten my promise made in my next-to-last sentence in my Post #17.
Hold on...here comes that wagon again! Jumping on!!!
Still interested in what you have to say about all this, Andy, but am having someone strap me down so as to stay put this time. Hope the straps hold.
90 feet? And you have those numbers...?
Hmm... To prove the mess is fine, got a Field Strength meter attachment? Might want to look into this....
How?
Quizzical look on his face...
Hmm... To prove the mess is fine, got a Field Strength meter attachment? Might want to look into this....
How?
By using F/S with all accessories installed and AMP off - so we don't "fool" our meter with extra power were not here for, it's losses, by Using Known Barrel Connector and taking out the various "installation accessories" - Check F.S. each time . The biggest "cut" or Jump - may indicate a poorly made Coax jumper section (intra-connection) or a poorly designed Bypass network (Inter-connection) - per the jumper.
Base F/S measurement with all stuff installed...
Use any METER as the F/S detector - All devices installed first, then remove one at a time...
Barrel end the Device out of the coax route.
Remove Amp - Barrel coax together then re-measure F/S - DO NOT move the F/S meter from initial location - we're checking for something here...
Leave Amp out - Barreled out - go to SWR meter - Barrel it out and recheck F/S - like you did with the amp above...
Soon, all devices except Radio should be barreled out from line so you have straight coax albeit barreled together
You can then - by removal of all devices - reinsert your SWR meter and recheck all your work and readings to see if mirroring event is occurring - then if you have such, the "mirror" is normal - it's a losses issue dealing with the install and locations of antenna and environment and not a problem with the coaxBase F/S measurement with all stuff installed...
Use any METER as the F/S detector - All devices installed first, then remove one at a time...
Barrel end the Device out of the coax route.
Remove Amp - Barrel coax together then re-measure F/S - DO NOT move the F/S meter from initial location - we're checking for something here...
Leave Amp out - Barreled out - go to SWR meter - Barrel it out and recheck F/S - like you did with the amp above...
Soon, all devices except Radio should be barreled out from line so you have straight coax albeit barreled together
- - note the F/S readings
- - if no change - you're fine - all losses and hits against power radiated are not caused by the Devices,
- F/S differs?
- Then you have to review the devices you've installed for impacts as losses either Reactive or by Impedance - as insertion losses you may need to correct or tune out the reactive components.
- I can tell by looks alone, you will be heard pressed to obtain flat readings by tuning alone - this may be a working enigma you can live with.
- The biggest clue is the "reflection mirror" of your "R" value at the amp.
No F/S meter. The 87' of coax is actually 75' plus a 12' jumper w/barrel connector. (More loss?)
Okay. Looks like my RM KL60 is the culprit.
Readings at Radio with Amp inline:
CH 1: 1.1
CH 20: 1.3 R= 62.2 X= 7.2
CH 40 1.5
Readings at Radio with no Amp connected:
CH1: 1.2
CH 20: 1.2 R= 44.6 EX= -5.7
CH 40: 1.2
Think?
There is a reflection there ...
62 and 44
12 = 62 - 50
6 = 50 - 44
So the biggest change is at the amp...
Nothing seriously bad, but note how it changes the SWR result too...
So Impedance bump - some - because the AMP is making the system look LONGER than it is.
Your Channel 1 lower - than 40 - meaning the antenna appears too long - but that is due to the amp - not the antenna itself because of the results achieved in your 2nd result.
62 and 44
12 = 62 - 50
6 = 50 - 44
So the biggest change is at the amp...
Nothing seriously bad, but note how it changes the SWR result too...
So Impedance bump - some - because the AMP is making the system look LONGER than it is.
Your Channel 1 lower - than 40 - meaning the antenna appears too long - but that is due to the amp - not the antenna itself because of the results achieved in your 2nd result.
10-4. Enough to noticeably impede performance?
Since none of the SWR or Resonance numbers are outlandish, I'm guessing not.
You may have a CMC issue - and to be honest, taking the amp out of line and trying to "sub in" a capacitor to see if the antenna looks LONGER or SHORTER in the amp - across the input side or even in series with the input line itself (if that is possible Across is far easier to see results - never had to work with those KL types too much, for as to the Boss was concerned - they were throwaways) even more than this last result - then you know the problem is the Amp not the antenna. Trying the option may also help with CMC for taming the mirror effect.
It can at least keep the coax "bump" the Amp induces into your system, attenuated.
No guarantees...
It's your PEP values that may hurt the amps ability to maintain linearity and even stay working; it may be more of a concern than the SWR bump in itself.
It can at least keep the coax "bump" the Amp induces into your system, attenuated.
No guarantees...
It's your PEP values that may hurt the amps ability to maintain linearity and even stay working; it may be more of a concern than the SWR bump in itself.
Getting Dizzy.
Am going to have to abide by Homer's rule.
Somewhere in the setup I had SWR of 1.08 on CH 20 with a R of 47 and a X of 0.2.
Need to lock up my analyzer and go about my business. Dadgumit.
OR, get a better antenna. And amp.
It's quit messing with it or buy a white jacket with extra long sleeves and the buckles on the back.
No kidding.
Here's what I finally did, Homer. I averaged ALL of the readings for CH1, CH20 and CH40 taken at all of the different locations.The result? Worries are over!
- No one is chatting at the moment.