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Proper SWR meter

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mdnanwelch7(at)hotmail.co
Guest

Posted: Thu Apr 22, 2010 11:05 am Post subject: Proper SWR meter

Electric gurus,

  

   I've got an SWR meter I borrowed from a neighbor who's a HAM radio buff.  The SWR meter is a Lafayette, stock no. 99-25835.  I'm waiting for the bnc/pl259 adapter to get here tomorrow, before I can use it.  (It has the bnc male/PL259 adapter to hook it up to my Icom A200).

  

   It was suggested to me to make sure it is the "right frequency meter", to be able to properly check for standing waves.  I wasn't aware of that aspect of an SWR meter.

   Does anyone know if this meter can properly check the standing waves on frequencies of an aircraft radio/antenna?      It only refers to "amateur radio stations".

  

 Thanks,

 Mike Welch

 		 	   		  The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with Hotmail.  Get busy.  [quote][b]

deej(at)deej.net
Guest

Posted: Thu Apr 22, 2010 11:46 am Post subject: Proper SWR meter

On 04/22/2010 03:00 PM, Mike Welch wrote:

 	  Quote: 	
		   The SWR meter is a Lafayette, stock no. 99-25835.  

  

   

   Does anyone know if this meter can properly check the standing waves

 on frequencies of an aircraft radio/antenna?      It only refers to

 "amateur radio stations".


	




	I was unable to find the exact specs for this unit, but I found a forum

thread on it here:

http://forums.qrz.com/showthread.php?t=88199

	If that thread is true, then if you are looking for a relative reading

(ie, a maximum or minimum reading), it might be okay.  If you are

looking for an exact correct numerical reading, then no.



	Typically, if you are tuning an antenna you are looking for a minimum

reading, so it would probably be okay.  Tune, check SWR, tune, check

SWR, etc.



	If you are inserting this inline to check the SWR reading of an

existing antenna installation and need an accurate number, then it

probably won't do you much good on aircraft freqs.



-Dj



-- 

Dj Merrill - N1JOV

Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/

Grumman Yankee Driver N9870L - http://deej.net/yankee/

mdnanwelch7(at)hotmail.co
Guest

Posted: Thu Apr 22, 2010 12:43 pm Post subject: Proper SWR meter

 > Typically, if you are tuning an antenna you are looking for a minimum

 	  Quote: 	
		   reading, so it would probably be okay. Tune, check SWR, tune, check

 SWR, etc.

 
	


 	  Quote: 	
		   -Dj

  
	


   Thanks for the reply, DJ.

  

   After reading some of those comments on it, now I'm concerned it may damage my Icom A200.

  

   The antenna I was planning on checking with it is my recently constructed "copper foil groundplane" antenna.

   I have plugged the antenna into the radio, and the local airport unicom replied with a "loud and clear", but they are only 1/3 of a mile away.  

  

   Should I not risk screwing up my Icom, and try to find a more appropriate SWR meter?

  

 Thanks, 

 Mike Welch

 GlaStar and Kolb MkIIIX builder



 		 	   		  Hotmail is redefining busy with tools for the New Busy. Get more from your inbox. See how.  [quote][b]

deej(at)deej.net
Guest

Posted: Thu Apr 22, 2010 1:14 pm Post subject: Proper SWR meter

On 04/22/2010 04:25 PM, Mike Welch wrote:



 	  Quote: 	
		     Should I not risk screwing up my Icom, and try to find a more

 appropriate SWR meter?


	




	I do not know anything about that particular SWR meter, so I can't say

for sure.  If you can find an SWR meter that covers the amateur radio

144Mhz band, that would probably be close enough so that you can tune

your antenna.  Any local amateur radio operators in your area?  I'm sure

they'd come out and help you for free just to see a cool project like an

airplane being built.  



	Try looking here:

http://www.qrz.com/db/?cmd=1

and then look up their name in the phone book and give them a call.



-Dj



-- 

Dj Merrill - N1JOV

Glastar Sportsman 2+2 Builder #7118 N421DJ - http://deej.net/sportsman/

Grumman Yankee Driver N9870L - http://deej.net/yankee/

mdnanwelch7(at)hotmail.co
Guest

Posted: Thu Apr 22, 2010 2:00 pm Post subject: Proper SWR meter

>Any local amateur radio operators in your area? I'm sure

 	  Quote: 	
		   they'd come out and help you for free just to see a cool project like an

 airplane being built. 

 -Dj


	


 DJ,

  

   Re: ham radio operators, yes.  That's where I got this SWR meter from.  Like I said in my original email, the instruction manual only refers to "amateur radios".

  

   Sounds to me as though I should be okay.  I'll get the adapter from Radio Shack tomorrow, and give it a try.

  

 Mike Welch

 GlaStar and MkIIIX builder

 		 	   		  Hotmail has tools for the New Busy. Search, chat and e-mail from your inbox. Learn more.  [quote][b]

kuffel(at)cyberport.net
Guest

Posted: Thu Apr 22, 2010 2:09 pm Post subject: Proper SWR meter

Mike,

  

 << SWR  meter is a Lafayette, stock no. 99-25835.  .. the "right frequency meter  >>

  

 Lafayette isn't known for excellence in  design.  There are two problems with the meter you mention.  First it  is specified for use only up to about 30 MHz, one fourth the frequency of the  aviation communication band around 120 MHz. As DJ mentions, it might be  able to determine a minimum bad.  But personally, I wouldn't trust  it.  And for sure it wouldn't tell you about the performance of your  antenna near the band edges, which is just as important as the "minimum"  frequency.

  

  Second, to work you must *transmit* power on  the frequencies of interest, a practice frowned upon by the FAA and the FCC  unless you are communicating with someone.  Current practice says to use an  input noise bridge antenna analyzer such as sold by MFJ.  Contact your  local ham radio club.  They will probably have one as part of the club's  equipment.  Even if not, for sure one of their members will have one and be  delighted to come over and help you tune/analyze your setup.

  

 To find your local ham club log on to  arrl.org.  In the upper right hand corner is a website search box.   Select the Category "Clubs" and press Go.  This takes you to a clubs  page.  On the left side enter your Zip code, select the desired mileage  range next to it and press Search at the bottom of this grey box.  Or fly  up to Whitefish Montana and I'll be happy to help you.

  

 Tom Kuffel, AL7AU

    [quote][b]

mdnanwelch7(at)hotmail.co
Guest

Posted: Thu Apr 22, 2010 5:06 pm Post subject: Proper SWR meter

Tom,

  

   Thanks for the tips.  I'll see if I can find a local ham operator guy to help get me squared away.

   If I came up to Whitefish, MT, I wouldn't have time to deal with the antenna....with my fishin' taking up all my time.  

  

 Thanks again,   Mike Welch



 		 	   		  The New Busy think 9 to 5 is a cute idea. Combine multiple calendars with Hotmail.  Get busy.  [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Thu Apr 22, 2010 5:26 pm Post subject: Proper SWR meter

At 04:59 PM 4/22/2010, you wrote:

  	  Quote: 	
		   Mike,

  

 << SWR meter is a Lafayette, stock no. 99-25835.  .. the "right frequency meter >>

  

 Lafayette isn't known for excellence in design.  There are two problems with the meter you mention.  First it is specified for use only up to about 30 MHz, one fourth the frequency of the aviation communication band around 120 MHz. As DJ mentions, it might be able to determine a minimum bad.  But personally, I wouldn't trust it.  And for sure it wouldn't tell you about the performance of your antenna near the band edges, which is just as important as the "minimum" frequency. 	


   Agreed. I blew away a lot of $time$ building matching

   harnesses "checked" with a similar transmission line

   reflectometer of this genre . . .



 [img]cid:7.1.0.9.0.20100422201433.0037fb48(at)aeroelectric.com.0[/img] 



   Optimized for the 3-30 Mhz range, these critters become

   VERY accommodating and tended to show that EVERYTHING you

   attached to it at 145 Mhz had a good SWR!



  	  Quote: 	
		    Second, to work you must *transmit* power on the frequencies of interest, a practice frowned upon by the FAA and the FCC unless you are communicating with someone.  Current practice says to use an input noise bridge antenna analyzer such as sold by MFJ.  Contact your local ham radio club.  They will probably have one as part of the club's equipment.  Even if not, for sure one of their members will have one and be delighted to come over and help you tune/analyze your setup. 	


    Actually, the MFJ259 is an active emitter too but in

    the milliwatt level. But the best part is that it's

    ability to accurately display antenna and transmission

    line characteristics is quite good at 130 Mhz.



    I use to rent one to the OBAM aviation community but

    wear and tear outgo was higher than rental income.



    Bob . . .

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kuffel(at)cyberport.net
Guest

Posted: Thu Apr 22, 2010 8:49 pm Post subject: Proper SWR meter

Me:

  

 <<  you must *transmit* power on the frequencies of interest, a  practice frowned upon by the FAA and the FCC unless you are communicating with  someone. >>

  

 Bob:

  

 <<   Actually, the MFJ259 is  an active emitter too but in  the milliwatt level. >>

  

 Absolutely true, but in this context all receivers  are "active emitters".  For example, Canadian police use a special receiver  to detect the miniscule signal emitted by radar detectors to enforce their  ban on such devices.  The point being made is the amount of power needed to  operate the old style SWR meters *will* cause appreciable interference to  other users while the MFJ259 and such for all practical purposes will  not.

  

 Tom Kuffel

    [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Apr 23, 2010 5:33 am Post subject: Proper SWR meter

At 11:46 PM 4/22/2010, you wrote:

  	  Quote: 	
		   Me:

  

 <<  you must *transmit* power on the frequencies of interest, a practice frowned upon by the FAA and the FCC unless you are communicating with someone. >>

  

 Bob:

  

 <<   Actually, the MFJ259 is an active emitter too but in  the milliwatt level. >>

  

 Absolutely true, but in this context all receivers are "active emitters".  For example, Canadian police use a special receiver to detect the miniscule signal emitted by radar detectors to enforce their ban on such devices.  The point being made is the amount of power needed to operate the old style SWR meters *will* cause appreciable interference to other users while the MFJ259 and such for all practical purposes will not. 	


    Sure, but that wasn't the point, the MFJ device one is

    looking for is not the "noise bridge antenna analyzer"

    or MFJ202. This network analyzer excited by a broadband

    noise source requires a receiver with a signal strength

    indicator tuned to the frequency of interest as part of

    the test equipment. Further their only noise bridge offering



     http://mfjenterprises.com/man/pdf/MFJ-202B.pdf



    is more of a system designer's instrument than

    a technicians test tool.



    Bob . . .    [quote][b]

earl_schroeder(at)juno.co
Guest

Posted: Fri Apr 23, 2010 5:45 am Post subject: Proper SWR meter

Bob wrote:

Actually, the MFJ259 is an active emitter too but in

   the milliwatt level. But the best part is that it's

   ability to accurately display antenna and transmission

   line characteristics is quite good at 130 Mhz.



   I use to rent one to the OBAM aviation community but

   wear and tear outgo was higher than rental income.



   Bob . . .



When you 'rented' the MFJ259, did you include a simplified instruction sheet?



As a proud owner of a MFJ259, I would like a 'cook book' type instructions tailored to the OBAM aviation community.



I would like to know all the theory etc but at this time do not have the time to invest in learning its complete capability and retaining it.  I am interested but short on time.  My Grandson currently has priority!



I just want to know how to correctly connect it and read the SWR.  Then some clues as to how to correct it if necessary.



Then I would like to assist my EAA chapter folks in checking their installations.  The MFJ259 sitting on the shelf isn't doing anyone an favors... (no, it isn't for sale at this time)  Earl

kuffel(at)cyberport.net
Guest

Posted: Fri Apr 23, 2010 8:41 am Post subject: Proper SWR meter

<<   Sure, but that wasn't the point, the MFJ device one  is

   looking for is not the "noise bridge antenna analyzer"

   or  MFJ202 >>

  

 As usual, Bob is correct.  I falsely  "remembered" my MFJ HF/VHF SWR Analyzer Model MFJ-259B used noise bridge  technology.  Should have checked my instruction manual first and used the  full, official name.  The Model MFJ-259 Analyzer is what you will  commonly find available from local ham radio operators/clubs.  The original  point remains, it is a much better tool to adjust aircraft antennas than the  Lafayette style SWR meters.

  

 Tom Kuffel

    [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Fri Apr 23, 2010 1:35 pm Post subject: Proper SWR meter

At 11:37 AM 4/23/2010, you wrote:

  	  Quote: 	
		   <<   Sure, but that wasn't the point, the MFJ device one is

    looking for is not the "noise bridge antenna analyzer"

    or MFJ202 >>

  

 As usual, Bob is correct.  I falsely "remembered" my MFJ HF/VHF SWR Analyzer Model MFJ-259B used noise bridge technology.  Should have checked my instruction manual first and used the full, official name.  The Model MFJ-259 Analyzer is what you will commonly find available from local ham radio operators/clubs.  The original point remains, it is a much better tool to adjust aircraft antennas than the Lafayette style SWR meters. 	


   ABSOLUTELY!! I've owned three of them

   and it's the first tool I pick up when there

   are questions of feed line and/or antenna

   quality to be explored.



   I used to have a noise-bridge. It does perform

   as advertised and was VERY reasonably priced because

   the heavy lifting for test equipment was the companion

   receiver not supplied. I think I gave that one away

   many moons ago.



   Bob . . .    [quote][b]

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Apr 24, 2010 7:27 am Post subject: Proper SWR meter

 	  Quote: 	
		  When you 'rented' the MFJ259, did you include a simplified instruction sheet?



As a proud owner of a MFJ259, I would like a 'cook book' type 

instructions tailored to the OBAM aviation community.



I would like to know all the theory etc but at this time do not have 

the time to invest in learning its complete capability and retaining 

it.  I am interested but short on time.  My Grandson currently has priority!



I just want to know how to correctly connect it and read the 

SWR.  Then some clues as to how to correct it if necessary.


	


   As a matter of fact, I think I did but it's

   on the computer in M.L.



   I'll see if I can did it up and post it early

   next week. If not, I'll write up a new one.

   It's pretty straight forward . . . perhaps

   a cognizant user of such devices will come

   up with a procedure before I get to it.



   Bob . . .

earl_schroeder(at)juno.co
Guest

Posted: Sat Apr 24, 2010 11:10 am Post subject: Proper SWR meter

I wrote:

 	  Quote: 	
		  When you 'rented' the MFJ259, did you include a simplified instruction sheet?


	


Bob wrote:

   I'll see if I can did it up and post it early

   next week. If not, I'll write up a new one.

My response:

Thanks very much!  I'll be watching for it from you or anyone.. Earl



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