Inverted "V" Attic Antenna Using Mobile Whips

[StrangeBrew]

.... Why would a $250 analyzer be considered a wise or nesessery investment? ....

With an analyzer you buy it once and it can make every antenna you set up from that point on perform better, even ones made from stuff that wasn't originally intended to be an antenna. They definitely aren't a necessity but having one opens up a lot of opportunities.

 

[222DBFL]

It's not all about vswr!! There are other factors. But hey, until you use one, you may say to heck with the cost. It's a tool and from my experience with them is they just make life so much easier when tuning an antenna or even trouble shooting an issue. Like I said, don't knock it until you have used one and see the light lol! JMHO.

 

[222DBFL]

Sometimes you gotta see it to believe it! That is what the old timer here said after seeing what his Shakespeare big stick looked like on one, lol! He ordered a new antenna that day! Anyway. Good day.

 

[Riverman]

You guesstimated darn close, Stellasstillarat. Almost to the penny.

It's just hard for me to justify the purchase of an analyzer. For $250 I can get another vintage radio or two (which is where my pleasure lies) and have money left over.

On another note, my biggest concern with these two antennas was "RF in the shack" since I didn't have enough coax to coil and make a choke. However, my SWR readings stay rock steady with me touching the radio, SWR meter, every connector, and moving the coax and jumper around. Also, my nose hairs don't tingle and those on the back of my neck don't stand up when I key the mic, so I'm guessing I have very little or none.

 

[The DB]

It's not all about vswr!! There are other factors.

This is true, yet when many people get an antenna analyzer all they use the increased abilities of the antenna analyzer to help them tune SWR... Its like they are stuck on SWR tuning, although in pretty much all cases it's the limit of what they know. This group doesn't care about anything other than SWR, and use all of the power of their shiny new toy that cost them a pretty penny to do essentially what they could do with a piece of $20 equipment that they already own...

Further, if you ask most CBrs, and even many ham's, that use antenna analyzers, they will tell you that the best possible tune is R=50 and X=0, which will get you that perfect SWR match people seek, and in most cases, if you are seeking performance, is not the best possible tune...

Its a shame really. You can get a much cheaper tool to assist in tuning antennas, one that doesn't cost much more than a cheap SWR meter, and it will help you tune antennas for performance as well as a much more expensive antenna analyzer, but no one ever mentions them anymore. I'm talking about a field strength meter. If you are tuning pre-made antennas, it is a field strength meter that you should get experience working with first as they can teach you some valuable lessons that you can later apply to using an antenna analyzer, should you ever get one...

In any case, his antenna seems to be working well. I don't see there being a need to get an expensive piece of equipment to tune it further...


The DB

 

[M0GVZ]

You guesstimated darn close, Stellasstillarat. Almost to the penny.

It's just hard for me to justify the purchase of an analyzer. For $250 I can get another vintage radio or two (which is where my pleasure lies) and have money left over.

But what good are they going to be other than ornaments if you have a crappy antenna? I assume you intend on using them?

 

[M0GVZ]

Further, if you ask most CBrs, and even many ham's, that use antenna analyzers, they will tell you that the best possible tune is R=50 and X=0, which will get you that perfect SWR match people seek, and in most cases, if you are seeking performance, is not the best possible tune...

This. For my mobile install for example, at X=0 the best value of R I could possibly hope for is 37 as it means my mobile is performing as well as a 1/4 wave over perfect ground which is a massive achievement for a mobile installation. A R value of 50 would mean I had some real serious losses.

 

[Riverman]

But what good are they going to be other than ornaments if you have a crappy antenna? I assume you intend on using them?

Ouch. That stung.

Guess I'll just have to take my chances.

 

[222DBFL]

And by no means was I suggesting he get one. I just agreed with the fact if used properly, they are a handy tool for antenna tuning and trouble shooting. If you are into building antennas and such, or had to tune a few antennas, then hey it might be worth the investment.

 

[binrat]

I had a 259b for a few years, rarely used it to its max potential. I ended trading it for an iP30z plus cash. It was a deal that I would have been stupid to turn down. I'm happy with the 30z as it does what I need.

 

[StrangeBrew]

.... I'm talking about a field strength meter. ....

Any recommendations for a decent field strength meter and info on how to use them? I haven't had much luck with them in the past but must admit that the ones I was using were at the low end of the quality spectrum and I didn't have much info available as far as operating one was concerned.

 

[zig zag]

Any recommendations for a decent field strength meter and info on how to use them? I haven't had much luck with them in the past but must admit that the ones I was using were at the low end of the quality spectrum and I didn't have much info available as far as operating one was concerned.

nice job on the attic antenna,,,

 

[M0GVZ]

Any recommendations for a decent field strength meter and info on how to use them?

Build your own to use with a digital multimeter.
http://www.zen22142.zen.co.uk/Circuits/rf/sfsm.htm

The idea is to use them to compare one antenna to another rather than for an absolute value because that's of little use. In this case even a cheap one will do the job OK although it won't be that linear in its readout.

How to use them? Set at a specific distance from the antenna, key up with a carrier mode (FM/CW) and take a reading. Change antenna or make modifications to the existing one you're testing, repeat at the same distance, compare the two readings. If reading A gives a reading of 50 and reading B gives a reading of 100, B has 3dB gain over A.

 

[Captain Kilowatt]

Another good thing about field strength meters is that you can use them when setting up a directonal antenna. Set it behind the antenna and tune the reflector for lowest signal strength. You can also easily experiment with various spacings too and actually see the results.

 

[The DB]

Any recommendations for a decent field strength meter and info on how to use them? I haven't had much luck with them in the past but must admit that the ones I was using were at the low end of the quality spectrum and I didn't have much info available as far as operating one was concerned.

I started with a cheap MFJ that cost me $30... I have a better one now though, but in essence how they are used are the same.

I put it as far away as I can get a reliable reading. As there are other fields generated by the antenna and not radiated, getting the field strength meter further away from the antenna to a point will get you more reliable results.

Using the MFJ meter mentioned above, on the base tune and while the radio is transmitting, I use the adjustment knob to center the needle over one of the marks, I use the middle mark. I make a change to the antenna (while the radio isn't transmitting of course) and note the effects on the needle. I continue to make adjustments until I find the tune on the antenna that peaks the signal (or no matter how to change an antenna from a certain point the signal on the field strength meter is weaker. With that meter at any point the needle is to far away from a mark I use the adjustment knob to recenter the needle on a mark.

I don't move the meter during tuning. I have been known to attach it to a broomstick, and tie that broomstick to a fence post, or stick it in the ground. However you do it you want the antenna and the field strength meter to not move while tuning.


The DB