FM and AM Band Antenna?

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Shortwavewave

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I bought a real nice AM/FM/MPX radio from Standard Radio Corp(dont know the mfg year). Its has a real wood case, real metel knobs.

It has an internal ferrite bar for AM, and picks up FM nicly without an antenna.

My question, Ive uploaded some pics to show that is has two FM ant terminals, as if it for a Dipole? What would I have to do to use a Yagi? or some type of other antenna?

Having some wire just thrown about looks kinda tacky for the FM dipole, I like my wires hidden, but its not a must.

The AM ant, I have used a Longwire, because a external loop seems to have no affect on this radio, Ive tryed 3 different Tuned Loops, and one Broadband Loop, I know the terminals are connected, other wise the longwire wouldnt work, and I know ground is working, Ive tested in with a Multimeter.

Point/Question Is What would be the best antenna to use for FM and AM on a older radio like this?

This should be a easy thing for me, but its got me scratching my head.

Thank you.





 
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gcgrotz

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For local reception I would use a twinlead dipole, check Radio Shack. If you are using an outdoor TV antenna with coax, just get a TV type coax-twinlead balun and connect it to the terminals.

See the other recent posting here for AM antenna ideas.
 

ka3jjz

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You didn't show us the back of the radio, which is where the real question lies :.>>

It would seem that the screws on the back of the set are just for an FM antenna. To get things like loops - as recommended (correctly) in other threads on this forum - to work for AM reception, likely as not you would need to disconnect the internal loop from the circuit and run a PL259 onto the back of the set using those wires.

73 Mike
 

ka3jjz

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I wouldn't worry about that, frankly. To be safest, I'd probably dig a little and see if I could turn up a service manual (and it would take some digging, as this stereo goes back aways, I'm sure) to be certain.
My first stop would be the Worldwide TV FM DX Association mailing list - it's quite likely someone there knows where that can be had. And here's the link (from their new website):

http://www.wtfda.info/

A nice little weekend project, I must say. 73 Mike
 
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ka3jjz

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Boy did I pull a DUH on that one! You would want a nice chassis mount SO239 on the back of the radio, and a PL259 on the cable from the loop to the new jack on the stereo.

DUH! Sri about that! 73 Mike
 

KC0QNB

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No so239, no pl259, use 75 ohm cable and an 300:75 balun hook the 300 ohm side to the fm teminals. buy/build an fm broadcast antenna, stick it out on your metal mast. run the cable from the antenna to the set. That radio is real nice looking and made by standard, probably the same standard that made two way radio gear.
Hook your am terminal to your shortwave antenna, yes that is a real ground screw hook it to a good ground, (you do have an antenna ground system right?)
 

ka3jjz

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That's assuming the FM and AM terminals (jacks) on the back of the set are wired together or feed both RF sections - which I kinda doubt, given that there's an internal loop. I once had a stereo not unlike that, and the FM antenna didn't do squat on AM. Besides, I can't think of any manufacturer of an antenna that was good on both AM and FM. Sometimes hooking a good Yagi up with the method you describe works, sometimes it doesn't make much difference.

Besides he's already tried connecting loops, and it didn't seem to work. Very likely the internal loop was not 'disconnected' (either physically or electrically) when the external loops were connected. That's pretty strong circumstantial evidence of isolated antenna feeds.

That's why getting a good service manual on the radio is a much better bet. 73 Mike
 
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ka5lqj

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My 2 "cents", LOL!

Hi Guys!

Take it from an old radio repairman and BCB/FM Dxer, be safe about hooking up ANY antenna
to the receiver. First of all, if the set doesn't have an isolation transformer to "block" a 'floating'
ground, you will get a nasty, 120 volt shock if the a/c plug is turned the wrong way.

The AM Broadcast side really doesn't need another antenna, but IF you could find an old, tube-
type set that wound anttenna on the back (inside) of the set (usually on thick fiber board. If the
leads of that Litz wire will reach, you can mount that on to a wood dowel and turn it for better
or different stations reception. This works when you have a high-powered AM'er and you have
another weaker station on the same frequency.

Now, for distant FM reception, I would suggest an outside aerial on a very tall mast with a rotor.
BE SURE that when erecting the set-up there is absolutely NO chance that you, the mast, or the
antenna will even come within 10 feet of a power line or house drop. Recently in Memphis, there
were two hams, father and son killed while putting up a fiberglass, 10 meter antenna. But, fiber-
glass doesn't conduct radio waves and the inside of the antenna was metal. The got too close and
the 7200 volt a/c line "flashed over". It killed the father outright, the son died later at the hospital.
The sadder thing was the son's small daughter witnessed the whole thing. I believe she was 7 years
old. She went for help, but it was too late.

Most FM antennas today have the 75 ohm connector to hook, quad-sheilded, coax. Be sure you get
enough coax. Depending on your location to a radio pager service, you could also get an FM antenna
amplifier (Radio $haft, LOL!). When you need to hook-up the coax to the antenna, use a "barrel"
matching transformer (75 to 300 ohms with spade lugs) Hook the lugs to the radio terminals and
Voila'! You're in business!

I hope this helps.

Respectfully submitted,
73,

Don/KA5LQJ
 

KC0QNB

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On some radio sets for an external am antenna there was a "tap" on the am loopstick that went to the am connector on the back.
Ernie, look and see, you have had the chassis out, whats in there?
I just looked at img3839 from your link looks to me like the white wire wound on the loopstick, may be the same white wires that are connected to the g and am screw am I right?
 
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Shortwavewave

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Thank you all for your help, only problem is untill I get a house and back yard I cant put up a mast in my apartment complex, BUT I can but up some sort of outdoor antennas, Loops, Verticals, the small stuff.

Here is a video about my radio http://www.youtube.com/watch?v=Ji4egdNI2q8
note: that the satations I was getting were with NO antenna

What would be the best FM yagi, not to big to get?

Also, for now I cant have a rotabable yagi, would would be some antennas I could make? A dipole? A vertical?

A 1/2wave dipole for aprx 98mhz would be 5ft
And a full wave vertical would be 10ft?

As for the AM antenna guess Ill just have to experament, perhaps my loops arnt big enough.
 

Shortwavewave

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Yes the white wire is connected to AM and G similur to a balun setup, that is what confused me because the Loops I used had no affect. BUT a longwire did
 

Shortwavewave

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OK got a new problem, LOL

Used the multimeter for the contiuity test, aka what touching each other

Well Both FM, AM and G terminals are all touching back and forth, side to side, you name it there touching some way form of fashion.

NOW I have blisters on my heard from sctatching LOL
 

prcguy

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The antenna connections on your receiver are typical for most receivers made for the last 40yrs or more, I think everyone is over analyzing the hookups. Its common to run the longest piece of wire for AM that you can and it complements the internal ferrite antenna. If your looking for FM broadcast DX then a yagi is nice, otherwise an omni directional "turnstile" works well, which is two crossed dipoles at 90deg to each other. Its common for mfrs to ground antenna connections with chokes or a 1meg ohm resistor for static dissipation. There is probably nothing wrong with your receiver.
prcguy
OK got a new problem, LOL

Used the multimeter for the contiuity test, aka what touching each other

Well Both FM, AM and G terminals are all touching back and forth, side to side, you name it there touching some way form of fashion.

NOW I have blisters on my heard from sctatching LOL
 

KC0QNB

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Just because they show continuity doesn't mean squat, there are coils resisters transistors more continuity than you can shake a stick at, I bet if you connect your ohm meter to the power plug it will show continuity, but it ain't shorted, because the fuse of circuit breaker didn't trip or blow in your house did it ?
Ernie don't worry about anything if it lights up and plays audio it is working just fine, but here is a warning, while you are pokin around in that thing remember in ohms or continuity settings, there is a voltage on your probes that could damage something very sensitive, and finding parts for that radio won't be easy. laterz R
 

kb2vxa

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Talking a simple answer to death again? Here it is boiled down, advice from an old pro who cut his teeth on that sort of radio. The two FM connectors on the left are for 300 ohm twin lead and the one on the right and ground are for 75 ohm coax. Of course the center goes to the right hand FM terminal and the shield to ground. (;->) The AM terminal is for any convenient length of wire AKA a random wire antenna, ground is not necessary, the power cord is RF ground. If you experience a lot of line noise try grounding that terminal to the closest cold water pipe or if not available hot water baseboard heating will do, even a steam radiator. Just make sure you have a CLEAN and tight connection, a poor connection is worse than none at all.
 

KC0QNB

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Talking a simple answer to death again? Here it is boiled down, advice from an old pro who cut his teeth on that sort of radio. The two FM connectors on the left are for 300 ohm twin lead and the one on the right and ground are for 75 ohm coax. Of course the center goes to the right hand FM terminal and the shield to ground. (;->) The AM terminal is for any convenient length of wire AKA a random wire antenna, ground is not necessary, the power cord is RF ground. If you experience a lot of line noise try grounding that terminal to the closest cold water pipe or if not available hot water baseboard heating will do, even a steam radiator. Just make sure you have a CLEAN and tight connection, a poor connection is worse than none at all.
Every outside antenna needs a ground for best results. I will bet the power cord is not grounded, probably a just a two wire cord connected to a transformer inside the radio.
Looking at the pictures that Ernie posted that set is old enough that I don't believe there is any provision for a 75 ohm hookup, just a 300 ohm twinlead connection. I have seen what you are talking about, I am glad they started putting "F" connectors on radios like that. I do agree however a clean tight connection is a must.
 
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