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AM antennas

D

dxer720

I just got a Sony XDR-S10HDiP. The FM is superb. It's the AM that I want to improve. The FM & AM selectivity are stunning, but the AM sensitivity is pretty poor. I'm just using the included AM loop.

Any suggestions for help the AM.

I've thought about getting an inductance-type antenna (Select-a-tenna or C. Crane's ferrite) to help, but I don't know if they can be used with the existing loop or not.

Is there an antenna that connects directly to the speaker-type AM antenna connections on the back of the radio?

I'd love to do a long-wire, but I live in an apartment.

Any suggestions?
 
The Twin Coil Ferrite from C. Crane is a great antenna. You may need to sit it in a window sill and remember it may need to be rotated until you get the best signal but it is a gem. It will set you back $100 though so get ready for that. I have a C. Crane Radio with a built in version of the TCF and it works fine in my apartment. Provided your radio has the approriate jacks for it's connection.
 
Other antennas to try--Terk Advantage, Grundig AN200 and Select-a-tenna (which seems to be available only at Univeral Radio).
 
I have a Terk Advantage & a C. Crane TCF. The TCF can be attached to an antenna input, or used passively with the mini antenna that comes with it. The select-a-tenna works just like the Terk. (no connections required.)
 
My question falls squarely in the "AM Antennas" category so with dxer720's indulgence, let me ask this: I have a 240' tower on my property about 30 miles south of Indianapolis. On the Tecsun portable radio, WSM (235 miles) is barely audible during the day...until I place the radio near the guy wire anchor...then WSM sounds just shy of a local. The entire dial is packed with strong signals. Now that's all well & fine as long as I want to stand out back holding the portable radio near the guy wires. There IS going to be a couple hundred feet of coax going to that location to feed my Icom receiver. What I'm looking for are suggestions on how to get that signal into the house. The guy anchor is grounded just a few feet from the anchor, so hooking the shield to ground & the center to the guy wire will likely not produce much signal as there will be a short almost directly across the coax. I'd suspect that leaving the coax shield off will raise the noise considerably, so that's out. I've thought about looping many turns of insulated wire around a guy wire & letting that inductor float above ground, but that may make me vulnerable to lightning--and would it couple much signal into the coax? I know how to make these things transmit on a single frequency in the AM band, but duplicating the wide band signal pickup my portable has at the other end of a coax cable? Has anyone already crossed this bridge?
 
Not off a tower guy wire, but other wires I've had available when staying at hotels, etc.
Loop the wire as you would imagine, connect the loop to the coax, and ground the shield of the coax.
Yes, then the coax is grounded at two places if you're connecting to a radio that has
an unbalanced input, but this should still get you the signal off the tower.
If it's balanced, like a coupling loop on a ferrite rod would be, then you've only got ground at the far end of the coax.
Then the major portion of current in the coax will be current induced, rather than simply becoming an antenna.
May require some experimentation with number of loops, loose/tight coupling, and best length of winding.

I have also coupled many signals into radios without AM antenna terminals by winding a few turns loosely around the ferrite
bar, then connecting the loop to a coax or tuned loop antenna. If I don't feel like opening the radio, a few turns wound around the
whole radio usually works, too.
 
Tom, Bob, or anyone else...

I spent many years in sales and often traveled by car. Although it was a rare occurence, there were occasions where I would pass under telephone/power line and the sound level and signal strength would increase dramatically. I assume this was a beverage antenna like effect, but I was never in a position to stop and test the potential for super-DX.

Has anyone else experienced this effect?
 
Icangelp said:
Tom, Bob, or anyone else...

I spent many years in sales and often traveled by car. Although it was a rare occurence, there were occasions where I would pass under telephone/power line and the sound level and signal strength would increase dramatically. I assume this was a beverage antenna like effect, but I was never in a position to stop and test the potential for super-DX.

Has anyone else experienced this effect?
Click to expand...

Many, Many times. In fact, there is a really good one with N-S behavior I drive under twice every day. It's a really high elevation powerline,
and whether it's not carrying current I don't know, but it's not radiating the normal sort of noise much of the time.

When driving (or wating for a traffic signal) under these, it sounds like 12 db of magic gain to the North/South.

In fact these are very close to audioguy's house....

Have you noticed this, audio?
 
Tom,

I don't know which power lines you're referring to, but I do notice an extremely strong effect when passing under the I-290 underpass on Illinois 53 just north of I-355. The middle one amplifies AM 1480 about 20 dB. It's amazing! Very consistent, too.
 
On Willow Rd, about a block west of the Edens expy, I think I''ll stop a while there on the way home in the morning and see
just what comes up if I tune around. Maybe the Dominick's lot will be perfect.
 
Tom Wells said:
On Willow Rd, about a block west of the Edens expy, I think I''ll stop a while there on the way home in the morning and see
just what comes up if I tune around. Maybe the Dominick's lot will be perfect.
Click to expand...
Could start a whole new form of AM DXing...power line DX. Maybe we should start a web site for listing the best places. :)
 
This looks interesting..Normally when I drive under big power lines (I mean big ones, not the ones supported by wooden poles), I hear electrical 60 Hz noise on AM.
 
I had a listen this morning. I'm not so sure about the "pattern" of pickup this gives.
There is definitely a lot of RF current being coupled in, but I'm hearing plenty of intermod products with strong locals.
I'd have to think the pickup would be in-line with the wire just like a bev antenna.
 
Interesting. I'm thinking the best location would be rural and far from local broadcasters.

I lived in the Kansas City area for a couple of years and made frequent car trips to Denver. I had a couple of sales stops along the way, and would usually take Old U.S. 40 for a while, rather than jump back on I-70.

There were a couple of places along the way where for a mile or so AM signals would 'boom', and one spot Denver stations would suddenly appear strong as a local, and then quickly fade to nothing. Never had the time to stop and listen, but there were definitely lines paralleling the road.

Back then the AM band was still the first priortiy for car radios, and car antennas were still poles. That might have helped things.
 
Tom Wells said:
Not off a tower guy wire, but other wires I've had available when staying at hotels, etc.
Loop the wire as you would imagine, connect the loop to the coax, and ground the shield of the coax.
Yes, then the coax is grounded at two places if you're connecting to a radio that has
an unbalanced input, but this should still get you the signal off the tower.
If it's balanced, like a coupling loop on a ferrite rod would be, then you've only got ground at the far end of the coax.
Then the major portion of current in the coax will be current induced, rather than simply becoming an antenna.
May require some experimentation with number of loops, loose/tight coupling, and best length of winding.

I have also coupled many signals into radios without AM antenna terminals by winding a few turns loosely around the ferrite
bar, then connecting the loop to a coax or tuned loop antenna. If I don't feel like opening the radio, a few turns wound around the
whole radio usually works, too.
Click to expand...
For closure, I tried several things to couple signals into coax from the guy wire & didn't do very well. Took another route : bought a roll of #12 insulated wire & climbed up to 180' & strung a (more or less) vertical long wire & fed it straight to the coax. That worked at least as well as the Tecsun portable near the guy anchor. Mission accomplished.
 
Icangelp said:
Tom, Bob, or anyone else...

I spent many years in sales and often traveled by car. Although it was a rare occurence, there were occasions where I would pass under telephone/power line and the sound level and signal strength would increase dramatically. I assume this was a beverage antenna like effect, but I was never in a position to stop and test the potential for super-DX.

Has anyone else experienced this effect?
Click to expand...

Beltline Highway (US-12/18) south of Madison, Wis.. Used to be a railroad crossing, just west of the American TV store.

As you drove across the tracks, Chicago AM signals would come WAY up.
 
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