Lighting Arrestors and coax use on antenna?

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RonGT

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If I were to build a ground plane base for one of my antennas,
I have a few questions.
Can I make it from non magnetic stainless steel?
I have some round stainless that is abput the right thickness.
Can I make the radials from stainless also?
is there a formula on how round the base is and how long the radials should be?
I plan on bolting the radials to the round base, 4 of them.
The base will be bolted to my antenna bracket.
My center antenna is fiberglass and 45" long 1/4 wave base loaded.
Will use RG-6 with ground because I have a roll of it, compression connectors.
Ron
 

mmckenna

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If I were to build a ground plane base for one of my antennas,
I have a few questions.
Can I make it from non magnetic stainless steel?
Absolutely. Stainless steel would be ideal.

I have some round stainless that is abput the right thickness.
Can I make the radials from stainless also?
Any electrically conductive material will work. I've made antennas out of copper tubing before. Nice thing about copper is that it's easy to solder the joints to prevent corrosion from becoming a problem later on. If you are using stainless and have the ability to TIG weld, you could make a nearly indestructible antenna.

is there a formula on how round the base is and how long the radials should be?
I plan on bolting the radials to the round base, 4 of them.
The base will be bolted to my antenna bracket.
My center antenna is fiberglass and 45" long 1/4 wave base loaded.
The ground radials would be about 1/4 wave. There are some pretty good calculators on line that will let you enter the frequency and it'll give you the exact measurements. Just pick the center of the FM broadcast band, or your favorite/desired frequency and use that.

Will use RG-6 with ground because I have a roll of it, compression connectors.
Ron
Good stuff and those connectors are easy to install. Should work out pretty well.
 

RonGT

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Thank you mmckenna,
The disk I used is about 8" across (round) non magnetic stainless probably 308 or 304 ss quality.
The radials I cut are 16" long and are 3/16" round , I blacksmith an eyelet on one end of each to go around a .200 stainless bolts I have, the radials are magnetic probably 316 ss
I can tig them on if need be but did drill the disk to fit on the angle bracket top and the bolts for the radials incase I have to change or keep trimming them. ( bolt cutters wont hardly cut them) but my Bimetal band saw will.
Could you point me in the direction of the formula on the net?
Thanks Ron
 

mmckenna

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For receiving, you don't need to be too concerned with exact length. Exact length comes into the equation when you are using a transmitter and are concerned about SWR/return losses. Just getting it close is enough.

Probably no need to TIG weld them if it's a good connection. If it starts acting up in a few years, you may need to disassemble and clean the joints. Other option would be to just bolt them and follow up with a quick tack weld, but that's probably not necessary.

Here's a calculator you can try:

Amateur Quarter Wave Ground Plane Antenna Calculator
 

prcguy

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What frequency is the antenna?
prcguy

If I were to build a ground plane base for one of my antennas,
I have a few questions.
Can I make it from non magnetic stainless steel?
I have some round stainless that is abput the right thickness.
Can I make the radials from stainless also?
is there a formula on how round the base is and how long the radials should be?
I plan on bolting the radials to the round base, 4 of them.
The base will be bolted to my antenna bracket.
My center antenna is fiberglass and 45" long 1/4 wave base loaded.
Will use RG-6 with ground because I have a roll of it, compression connectors.
Ron
 

RonGT

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Thanks, The calculator is only in MHZ
isn't AM band in the 500-1700 KHZ?
Sorry I do not have a meter to check the frequency pcrguy,
Ron
 

mmckenna

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Thanks, The calculator is only in MHZ
isn't AM band in the 500-1700 KHZ?
Sorry I do not have a meter to check the frequency pcrguy,
Ron
Yes. You are not going to be able to make a 1/4 wave vertical for the AM broadcast band. A 1/4 wave antenna for 1000KHz would be close to 250 feet tall and need equivalent ground radials. You are much better off getting a loop antenna.
 

mmckenna

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You can make a 1/4 wave vertical for the FM broadcast band pretty easily.

Either way, vertical antennas won't work so well on AM broadcast band since they'll pick up stuff from all directions. Loop or rod antennas work better since they are directional. Turning the antenna slightly will help improve reception or null out stuff you don't want to hear.
Even on the FM broadcast side, using a directional antenna is going to be a much better solution.

I think 1/4 wave verticals are not the right choice for what you are trying to do here. I really think you either need to purchase or make a dedicated FM broadcast directional antenna, even an old style TV antenna will work.
For the AM broadcast side, you really do need to be looking at a good loop or external antenna. Vertical will be pretty much useless.
 

RonGT

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splitter?

Does anyone know where I could find and AM/FM splitter band separator?
I have one radio that has the 75 Ohm f connector on it and the am part has the twin lead type.
If I had a separator like an CATV splitter antenna in and FM AM out I could use the same antenna.
Would a splitter from a CATV or Satellite TV work?
Ron
 

Rred

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AM broadcast band is so good at penetrating things, that typically you can liberate one of the 3" long ferrite rod antennas from any dead transistor radio, attach it directly to those 300 ohm leads behind the radio, and it will outperform any fancy antenna splitter and matches you can find. (Unless you really need to get out of a cave that's blocking all AM signals.) And you're avoiding the compromised performance from an antenna that can't serve two masters equally well, no matter how you split it.

FWIW.
 

RonGT

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no reception!

Ok its not a cave which could possibly be better than where I am.
I am in a very rural area for AM/FM reception.
I know its hard to realize that when 90% of the populace live near or in a city.
Plus I work in metal buildings with LED and florescent lights.
There is NO, NO reception what so ever,
Loop antennas and ferrite bars do nothing in the buildings, I have a pile of them I have made.
BUT my vehicle radio picks up perfectly the very few distant stations while sitting with in feet of the buildings.
I figure that with a better than a factory Vehicle antenna attached to the top of the building that even that would improve.
I may be wrong?
So I purchased one of the better quality Vehicle radios that I have listened to, made the necessary modifications so I can at least have the radio in the building so I don't have to go outside and tune and power on the radio,
Maybe I am wrong and none of it will work but that is what I have now, nothing.
All the tube type , transistor type radios do nothing unless I am outside and have a loop antenna attached, but I work inside and a loop antenna on top of the building , well I just cant see it.
A wire antenna strung along a fence or building or tree is not going to happen here, no way for that to work.
So my question is there a band separator that is for AM ?FM as on of my better desk radios has the F connection for FM and the 2 screws for the twin lead or am I just guessing there is such a splitter.
I figure that the factory Vehicle radio is a better radio that type you can buy for the city dwelling population and it picks up great reception while traveling at interstate speeds with a crummy 32" stainless rod,
It would work great with a great antenna and standing still and with great grounds to earth.
Ron
 

mmckenna

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Yes, you can get a band separator. InLogis Pixel Technologies AF-KIT AM/FM receiver to an AFHD-4 (AF-KIT) from Solid Signal

I think the issue you seem to have is that the building itself has enough RF blocking properties that it's going to require all your antennas to be outside.

An AM loop will work if it's outside the building and fed inside via coaxial cable. Unfortunately commercial made AM loop antennas like this are expensive.
FM antenna will be much easier, as I've mentioned above.

If AM broadcast radio is an absolute requirement, you are going to need to have an antenna mounted outside the building.

I think mounting a vehicle antenna outside the structure might be a good option. Since the vertical antennas on cars works well for AM and FM due to the way it's interfaced inside the radio and how the antenna is designed, you should be able to do this by just extending the coax inside the building and connecting to the radio.

I think you are on the right track with this, but I'd caution against over thinking it. Trying a vehicle antenna mounted outside the building and connected back to the radio via coax is a cheap test to try. If that doesn't work satisfactorily, then start looking for the splitter/combiner, FM antenna, AM loop, etc. But, that's going to cost more.
 

Rred

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A metal building, whether it is a modern prefab or a leftover Quonset hut, still counts as a cave, as far as radio waves are concerned.
You could call it a "Faraday Cave". Doesn't matter if it is ten feet of concrete over steel beams, or just good sheet steel paneling, that's enough to mess up radios.
I knew someone in a sub-street level plant in downtown Manhattan that had the same problem. Shoved a coat hanger on a wire up an air shaft far enough to "see" daylight, and he had the only working radio in that facility. Nothing fancy, just a wire into daylight.
 

RonGT

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Thank for the link its something I have searched for.
Yep no reception, tried all the slinky antennas, Ferrite bars, coils inside PVC, coils on wood frames, air capacitors, worked good but not weather proof, decided to go the vehicle radio as it has something built into it that makes it work with just a vertical whip.
So I have the parts just about finished up, the splitter is for an old Sangean that seems to receive better than most I have had so its up to the AC Delco and the Sangean for now.
Ron
 
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