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variance in swr readings

W

Whiplash-265

Active Member
Aug 14, 2011
280
17
28
59
Ontario, Canada
up until now i've been running an swr meter in-line (PDC1 Compact CB SWR/Power Meter) on my mobile and been turning out good results
radio to 24" patch cable to swr to antenna cable/antenna and power juiced (so let's say 60w) and between 1 and 40 AM i'm getting between 1.3 and 1.5 deadkey
dropped the spendies yesterday and picked up a 259B
so now 259b to antenna cable/antenna and i'm getting 1.8 to 2.3

so am i correct in my assumption that my PDC1 is a POS and the 259b is what i need to re-tune by?
and if the cheapie meter is gonna be pulled from the equation (always in-line) is it safe to run a female to female between the patch and the antenna coax?

i'll have a few more questions as i become more familiar with this thing :)

thanks in advance
 

I never much cared for PDC or Dosy meters. I would trust the analyzer.

The adapter is safe to use, but you'll have the usual perfectionists proclaim insertion loss effects.
 
Whiplash-265 said:
up until now i've been running an swr meter in-line (PDC1 Compact CB SWR/Power Meter) on my mobile and been turning out good results
radio to 24" patch cable to swr to antenna cable/antenna and power juiced (so let's say 60w) and between 1 and 40 AM i'm getting between 1.3 and 1.5 deadkey
dropped the spendies yesterday and picked up a 259B
so now 259b to antenna cable/antenna and i'm getting 1.8 to 2.3

so am i correct in my assumption that my PDC1 is a POS and the 259b is what i need to re-tune by?
and if the cheapie meter is gonna be pulled from the equation (always in-line) is it safe to run a female to female between the patch and the antenna coax?

i'll have a few more questions as i become more familiar with this thing :)

thanks in advance
Click to expand...


For your information when you have the analyzer hooked to the antenna make sure no one keys some watts close by or that MFJ will be headed back to the factory for repair.
 
thanks psycho, will definitely take that advice :)

damn there's a lot of shyt to learn about this li'l tool :)
it's a lot to absorb for us "not so electronically minded" to grasp :unsure:
 
Whiplash-265 said:
up until now i've been running an swr meter in-line (PDC1 Compact CB SWR/Power Meter) on my mobile and been turning out good results
radio to 24" patch cable to swr to antenna cable/antenna and power juiced (so let's say 60w) and between 1 and 40 AM i'm getting between 1.3 and 1.5 deadkey
dropped the spendies yesterday and picked up a 259B
so now 259b to antenna cable/antenna and i'm getting 1.8 to 2.3

so am i correct in my assumption that my PDC1 is a POS and the 259b is what i need to re-tune by?
and if the cheapie meter is gonna be pulled from the equation (always in-line) is it safe to run a female to female between the patch and the antenna coax?

i'll have a few more questions as i become more familiar with this thing :)

thanks in advance
Click to expand...
your answer to what is in bold; yes its safe, how ever it can cause RF bleeding but ur in the mobile ...dont worry. the pdc = POS. the 259b = awesome. do what the analyzer says. for get the meter inline.(y) be careful with the analyzer psycho is right it can get real messed up real quick.
 
An antenna analyzer is not a simple thing to use correctly. It's just like any tool, you have to know what it's capable of doing, and what it's telling you. An antenna analyzer has advantages over an SWR meter, it can tell you what the SWR is, but the biggy, it also can tell you if the antenna is resonant. An SWR meter can't tell you anything about resonance. The difference between that analyzer and an SWR meter is the 'R' (resistance) and the 'X' (reactance) that the analyzer tells you about. The best possible 'R' and 'X' is, 50 and 0. That's 50 ohms of resistance and zero reactance. Why's that important? Cuz that 'X', reactance, doesn't contribute to radiating anything. So, you want as little of it as you can get. If you watch that 'R' and 'X' and the SWR meter, you'll see that there will be several places where the SWR meter says things are good, and the 'R' and 'X' aren't anywhere near good. When you find the frequency where they all agree as to what's good, you've found where that antenna is resonant and impedance matched, where it's 'tuned' the best. That SWR meter and the 'R's and 'X's don't always agree. It's not bad once you get the hang of it, it's the 'getting there' that's a real PITA, right?
- 'Doc
 
Morse123 said:
your answer to what is in bold; yes its safe, how ever it can cause RF bleeding but ur in the mobile ...dont worry. the pdc = POS. the 259b = awesome. do what the analyzer says. for get the meter inline.(y) be careful with the analyzer psycho is right it can get real messed up real quick.
Click to expand...

my prob is i have the radio mounted in-dash so i'd really love to leave in the 2' patch. It's either the POS meter or a f/f. Meter for now i guess, it at least give me a quick reference..
 
W5LZ said:
An antenna analyzer is not a simple thing to use correctly. It's just like any tool, you have to know what it's capable of doing, and what it's telling you. An antenna analyzer has advantages over an SWR meter, it can tell you what the SWR is, but the biggy, it also can tell you if the antenna is resonant. An SWR meter can't tell you anything about resonance. The difference between that analyzer and an SWR meter is the 'R' (resistance) and the 'X' (reactance) that the analyzer tells you about. The best possible 'R' and 'X' is, 50 and 0. That's 50 ohms of resistance and zero reactance. Why's that important? Cuz that 'X', reactance, doesn't contribute to radiating anything. So, you want as little of it as you can get. If you watch that 'R' and 'X' and the SWR meter, you'll see that there will be several places where the SWR meter says things are good, and the 'R' and 'X' aren't anywhere near good. When you find the frequency where they all agree as to what's good, you've found where that antenna is resonant and impedance matched, where it's 'tuned' the best. That SWR meter and the 'R's and 'X's don't always agree. It's not bad once you get the hang of it, it's the 'getting there' that's a real PITA, right?
- 'Doc
Click to expand...

i was reading about that Doc (RX....appropriate you'd know about that lol) but haven't had a chance to get her back onto the coax cuz of work. Have today off tho so will test things out again. I'm aiming for 27.555 as my reference and had a nice swr that was lowest there and climbed up going either up or down the frequencies...perfect scenario. will see what my r/x shows and report back

again, much thanks gentlemen!!
 
I'm surprised no one asked (since it's a mobile install) what kind of antenna is being used and how/where it's mounted on the vehicle. That alone could have quite a bit to do with the swr concern.

A mag mount on the trunk lid or tool box of a truck vs. a 102" stainless whip mounted up high and properly to the body of the vehicle (as an example). Both will behave differently to changes in power and nearby obstacles.
 
hey Ratso

magnet on pickup truck roof...Wilson 5000 on Ram Quadcab mounted towards rear/center due to coax restrictions
swr results between power output are resolved from what it used to be after i changed the stock 259 connector to a soldered one...no change now between 4w and 75w (257HP)
we have a sports-plex out this way so i drive over there for my tests...big open fields and the nearest thing to a one storey building is easily a few hundred feet away
windows up, doors closed :)

got a chance to run thru the bands again and got these results

26.965 1.4 swr r=65 x=12 z=67 o=0
27.555 1.4 swr r=35 x=06 z=36 o=0 -efficiency (coax test only or not?) but...96%
28.000 2.6 swr r=26 x=10 z=29 o=15

while i was out there i tried out the 802 as well
that's one weird pattern i tell ya lol..i didnt map it, but did a walk around and it's all drivers side, side and rear...not what i expected at all lol
 
Sorry, I was referring to this;
"A mag mount on the trunk lid or tool box of a truck vs. a 102" stainless whip mounted up high and properly to the body of the vehicle (as an example). Both will behave differently to changes in power and nearby obstacles."
Sure, two antennas mounted in different places would act differently, but this wasn't about that, it's only about one antenna and one mounting place.
[Lately, my posts seem to be lagging behind a bit. I figure that's because of delays in the internet or how I'm accessing the internet. This isn't the first time or the only forum/website that it happens with. No idea why.]
 

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