Interesting Antenna Experiment

[SAR923]

I have a Pro92 I use as a secondary scanner in my office. I mounted one of those crappy RS mag mount antennas on a steel plate about 10 feet above the office window instead of using the rubber duck since the computer noise was driving the Pro92 crazy. It worked OK but trunk systems more than 10 or 15 miles away were impossible and the UHF performance was mediocre at best.

I happened to have one of the RS Bidirectional (15-206) amplifers around and thought I would hook it up as a lark to see if it made any difference. All I needed was an F to BNC adaptor and a BNC to F adaptor to make it work. The specs are 54 mHz to 1000 Mhz range so I figured I had nothing to lose except the price of two adaptors.

The results were nothing short of amazing. I'm now picking up trunk systems 50 miles away with full quieting. I can pick up UHF signals from San Jose, which is about 70 miles from me. I can actually hear the train mobile uints on the UP system from the Roseville yard, which is about 50 miles away. There's been no increase in intermod and there's actually so much traffic from BART, Richmond, and Oakland that I've had to lock them out to have any chance of hearing what's happening in my area. I haven't noticed much degradation at all on low band VHF since CHP is the big user out here and they have plenty of power. If you listen primarily to low band VHF, this might not owrk for you.

For those of you who can't mount a roof antenna, this might be a viable alternative. I have no idea if this is an interaction that works only wth the RS mag mount but I imagine it would work with any mobile antenna. I'm now kind of jealous because my "hyped up" Pro 92 will pick up things my Pro96 running off a a dipole on 30 foor mast won't, digital excepted of course.

 

[loumaag]

Jim, I am curious about this setup. Is the number you put up there accurate? It doesn't return much info on the RS site. I did spot a 15-2506, is this what you meant?

 

[SAR923]

Sorry, Lou, 15-2506 is correct. I've been listening to this set up for the last few hours and I've heard trunk systems I can't get on my Pro96 with the discone. I know the Pro92 has a tighter front end than the Pro96 so maybe this amplifier opens the front end enough to make it a really sensitive receiver. I tried the same setup on my Pro96 and the results were terrible. I couldn't hear anything unless the attenuator was on every VHF and UHF frequency. Did nothing to help 800 mHz. There's something about this amp that turns the Pro92 into a pretty hot receiver. Even the air frequencies come in better.

 

[ReceiverBeaver]

Hi Jim, Excellent !! One of the best things about the radio hobby is our ability to experiment. You never can tell how a gizmo or antenna or radio will perform under one's specific local conditions.....until ya try it. Well done dude. I'm glad it worked for you. One shouldn't be afraid to try something like that.

 

[N_Jay]

If an amp at the receiver end helpts that much, then your receiver is deaf!

As for the "You don't know till you try", that is very true if you don't take the time to understand the issues.

Hmmm, lets pour random liquids into the gas tank and see if the car runs better?

I mean, "YOU DON'T KNOW UNLESS YOU TRY!"

Hmmm, lets take random herbs till you feel better?

I mean, "YOU DON'T KNOW UNLESS YOU TRY!"

Hmmm, Lets dance around till it rains?

I mean, "YOU DON'T KNOW UNLESS YOU TRY!"

(Ever wonder where superstitions come from?)

 

[AZScanner]

Hmmm, lets pour random liquids into the gas tank and see if the car runs better?

I mean, "YOU DON'T KNOW UNLESS YOU TRY!"

Thank you N_Jay, always a shining beacon of optimism, and an inspiration to us all..... :wink: Seems like everytime there is someone who has found a way to improve their reception, almost as if on cue, here comes N_Jay to rain on their parade.

Unlike pouring random liquids into a gas tank or ingesting random herbs, experimenting with a small signal booster isn't going to damage anything. So your comments are about as relevant as they are helpful. I'm still using rabbit ears N_Jay, they work just fine for me. This amplifier works just fine for him. Why is that such a problem? Seems like it just drives you nuts when people don't use a bonafide "Scanner Antenna" for scanning. I find that about as nutty as berating someone for bathing with HAND soap instead of body wash. Who cares, so long as the end result is what you want?!

N_Jay why don't you write Antenna Design and Installation for Dummies and show us all how it's done. Not only would that be better than posting insults, but it would make you some money too - I mean, just look at all of us rubes who don't know jack about antennas.... you'll make a fortune.

-AZ

 

[SAR923]

If an amp at the receiver end helpts that much, then your receiver is deaf!

Obviously it means my receiver is deaf! This has been an issue with the PRO92 since it first came out. The 15-2506 amp apparently acts to overcome the receiver deafness with no ill effects. This was not a "random" act, as you put it. It was a reasonable and safe experiment to see if the 92 would perform better and the results have been spectacular. Since I assume we are are all here to help each other have a better scanning experience, posting my results might help others that have the same problem.

I've been working with radios for a long time. Churlish response like yours don't bother me although I expect this type of juvenile reaction from usenet and not here. The real problem with such a disrespectful response is you scare off people with less experience who may also have helpful information to post.

I don't intend to start a flame war here. I'll be happy to answer any constructive questions from others about my setup but I'll be ignoring your rants in the future.

 

[N_Jay]

Hmmm, lets pour random liquids into the gas tank and see if the car runs better?

I mean, "YOU DON'T KNOW UNLESS YOU TRY!"

Thank you N_Jay, always a shining beacon of optimism, and an inspiration to us all..... :wink: Seems like everytime there is someone who has found a way to improve their reception, almost as if on cue, here comes N_Jay to rain on their parade.

-AZ

I guess you missed the comment;
"As for the "You don't know till you try", that is very true if you don't take the time to understand the issues."

Experiment: the act of conducting a controlled test or investigation

I would ENCOURAGE all with interest to take just a little time and effort to learn a bit and then EXPERIMENT based on that knowlege (Building more knowlege), rather than pure trial and error, likely building more superstitions.

 

[nexus]

Hmmm, lets pour random liquids into the gas tank and see if the car runs better?
I mean, "YOU DON'T KNOW UNLESS YOU TRY!"

Thank you N_Jay, always a shining beacon of optimism, and an inspiration to us all..... :wink: Seems like everytime there is someone who has found a way to improve their reception, almost as if on cue, here comes N_Jay to rain on their parade.
-AZ

Dark Helmet: Who made that man a gunner?
Maj. *******: I did, sir. He's my cousin.
Dark Helmet: Who is he?
Col. Sandurz: He's an *******, sir.
Dark Helmet: I know that. What's his name?
Col. Sandurz: That is his name, sir. *******, Major *******.
Dark Helmet: And his cousin?
Col. Sandurz: He's an ******* too, sir. Gunner's Mate, First Class, Philip *******.
Dark Helmet: How many *******s we got on this ship, any how?
Everyone: Yo!
Dark Helmet: I knew it. I'm surrounded by *******s. Keep firing, *******s!

 

[Tweekerbob]

N_Jay:

There is also something called a control in an experiment. His control was his pro-92 connected to the magmount w/o the CATV amp. He received less than adequate reception.

The experimental side was introducing the CATV amp to "see" if this would improve his reception. All other variables being the same, this is a safe and simple experiment.

Already knowing his receiver was totally deaf, tone deaf, or just deaf in one ear, he theorized the addition of a broadband amp (such as a CATV amp, since CATV channels have little to no spacing and since most amps are continuous over a range of frequencies) would improve his reception.

From this I conclude that Jim has the knowledge required to conduct this experiment. He knows that his receiver is deaf in some way and he knows that an amplifier has the POTENTIAL to increase the sensitivity of his receiver and thus his overall reception. (POTENTIAL read "you don't know until you try")

Nowhere did he come up with just a guess, like taping a lucky rabbit's foot to the back of the PRO-92 in hopes of improving his reception.

BTW, can you prove that rain dances don't work? Seem to work to me; they always stop dancing when it starts raining (even if takes a few months). They have a 100% success rate.

Ryan

 

[AZScanner]

Dark Helmet: Who made that man a gunner?
Maj. *******: I did, sir. He's my cousin.
Dark Helmet: Who is he?
Col. Sandurz: He's an *******, sir.
Dark Helmet: I know that. What's his name?
Col. Sandurz: That is his name, sir. *******, Major *******.
Dark Helmet: And his cousin?
Col. Sandurz: He's an ******* too, sir. Gunner's Mate, First Class, Philip *******.
Dark Helmet: How many *******s we got on this ship, any how?
Everyone: Yo!
Dark Helmet: I knew it. I'm surrounded by *******s. Keep firing, *******s!

:lol: Another Spaceballs fan....

My favorite part was this one:

Dark Helmet: Did you see anything?
Col Sanders: No sir! I didn't see you playing with your dolls again sir!
Dark Helmet: Good!

-AZ

 

[nexus]

AhhahHAHahHA

I'm a Mel Brooks FAN! But since I'm a fan of sci-fi and star wars especially, that makes spaceballs one of my all time favorites.

My favorite was:

"Sir, I think you should come see this."

"What is it?"

"Sir, I lost the beeps, the sweeps, and the creeps."

"You lost the what, the what and the what?"

"You know, the beeps, (making beeping sound), the sweeps (making a sweeping sound) and the creeps (making an arcade sound)."

"That's not all he's lost..."

Or...

Sir, it's megamaid...
Well what about her?
She's gone from SUCK to BLOW!

ROFLMAO... I gotta pull out that dvd tonight and watch it hahah

 

[N_Jay]

Hi Jim, Excellent !! One of the best things about the radio hobby is our ability to experiment. You never can tell how a gizmo or antenna or radio will perform under one's specific local conditions.....until ya try it. Well done dude. I'm glad it worked for you. One shouldn't be afraid to try something like that.

Did anyone notice my response was to this post? :wink:

Not to your original post, SAR2401:evil:

 

[AZScanner]

I would ENCOURAGE all with interest to take just a little time and effort to learn a bit and then EXPERIMENT based on that knowlege (Building more knowlege), rather than pure trial and error, likely building more superstitions.

Well, I'm sorry I jumped on you N_Jay, I did apparently miss something in your first post. But I'm serious about that book. There's far too few references out there for the casual scanner listener when it comes to antennas. I've tried to read up on antenna design and theory, only to give up in disgust. Why? I'll show you. Here's a sample from hamuniverse.com:

The Yagi antenna's basic design is a "resonant" fed dipole (the fed dipole
is the driven element ), with one or more parasitic elements.
These parasitic elements are called the "reflector"and the "directors."
A dipole element will be "resonant" when its electrical length
is 1/2 of the wavelength of the frequency applied to its feedpoint.

Really. And in English that means..... what? That's my point. The whole page reads like that. YUCK! I would love to find something that explains how to build a good antenna in plain simple english, what the different types are, whats good, what's bad what works and why it works, what doesn't and why it doesn't. Instead all I find is stuff like this. Help us all out - is there a place online or even a book that exists anywhere that doesn't read like corporate case law? I don't want to spend months studying for a ham license so I can understand these antenna websites.

-AZ

 

[astrodanco]

There is also something called a control in an experiment. His control was his pro-92 connected to the magmount w/o the CATV amp. He received less than adequate reception.

I thought the concensous on the net is that the RS magmount antenna is junk? I'd try a better antenna (and better coax) before concluding much of anything. Both Antenex and Larsen make better antennas and magmounts than Radio Shack.

 

[SAR923]

There is also something called a control in an experiment. His control was his pro-92 connected to the magmount w/o the CATV amp. He received less than adequate reception.

I thought the concensous on the net is that the RS magmount antenna is junk? I'd try a better antenna (and better coax) before concluding much of anything. Both Antenex and Larsen make better antennas and magmounts than Radio Shack.

Tried that with a Larsen already. It was marginally better than the RS mag mount but not by an order of magnitude. I don't think the RS mag mount is that bad for reception, especially if you do the cutting mod that's posted here. It's the build quality that's bad. I wouldn't put on on the roof of my truck but it's good enough mounted on the side of a wall.

I swapped out the RS mag mount with my Larsen this morning just so I wouldn't be doing any "random" experiments. The RS mag mount seemed slightly more sensitive in the 800 mHz band, picking up more talk groups, while the Larsen seemed to be slighty more sensitive in the UHF bands. Neither was a clear winner. When I disconnected the amp, they were both equally deaf so the amp is the thing that has caused the change.

Remember I'm also comparing results with the same radio hooked to dipole on a 30 foot mast. It performs better than even the dipole when used with the mag mount and the and the amp. I tried the amp with the dipole and the receiver denses becuase of front end overload. It seems the combination of the less efficient mag mount and the amp is the ideal combination for me in terms of better overall reception. YMMV.

 

[ReceiverBeaver]

ReceiverBeaver agrees with AZScanner who also notices that NJay the Omnipotent is always quickly around to piss on anybody's parade.

Perhaps NJay is displeased that ReceiverBeaver will not sell him any delicious and nutricious beaver sandwiches at the customary RR discounted price.

NO delicious and nutricious discount priced beaver sandwiches for NJay the Omnipotent !!!!!!!!!!!!!!!!!!!!

Full retail price only for you

 

[N_Jay]

. .

NO delicious and nutricious discount priced beaver sandwiches for NJay the Omnipotent !!!!!!!!!!!!!!!!!!!!

Full retail price only for you

There is a HUGE difference between knowing what you are talking about and knowing everything. :wink:

Some people don't know much, but still know what they are talking about. :wink:

Others know quite a lot, but still DON'T know what they are talking about! :evil:

 

[astrodanco]

I tried the amp with the dipole and the receiver denses becuase of front end overload.

In this particular case, I hope you're placing the amp at the antenna rather than the receiver end of the coax. Of course you are, right?

 

[AZScanner]

I tried the amp with the dipole and the receiver denses becuase of front end overload.

In this particular case, I hope you're placing the amp at the antenna rather than the receiver end of the coax. Of course you are, right?

Probably not actually, since the receiver end is so much easier to get to. Remember, the antenna end is atop a 30' mast. Plus I don't think the amp was meant to be outside in the weather.

But this might be a viable alternative to a base antenna for those of us who (like me) live in an apartment or other area where a base antenna is either prohibited or just not practical. It's certainly worth trying - if it doesn't work you can always return the amp. I might give it a try, just to see if it helps any, as superstitious as that may be.... :wink:

-AZ