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March 12, 2010

Comments

Andreas

Don't invest in more receivers. Invest in better antennas. If you can't build an outdoor antenna, try with a magnetic loop antenna:

e.g. homebrew like this one http://www.kr1st.com/swlloop.htm

All my shortwave radios (Standard C6500, Yaesu FRG-7, ATS-803a, Sony ICF-5900W, Panasonic RF-2200, RP-2100 etcetera) extremely benefit from my homebrew magnetic loop antenna.

Especially on the tropical bands reception is much better than with telescope antennas or a random wire via preselector. Just my 2 cent, of course your mileage may vary.

But let me add one thing: maybe it's not a matter of reception quality that makes you searching for another radio, another radio and another radio... maybe that's just the beginning of a collector's virus ;)

Michael Salmons

That's an interesting antenna design, Andreas, thanks. And you're probably right about my radio "problems..."

Shawn Patrick

Always the question SWL have been trying to answer, what is the best antenna. There is no one "correct" answer.

Location of the antenna even more than the antenna itself is the key. I can lay 40 feet of speaker wire and get wonderful reception where I live. But if I go to my father's and do it, I get nothing but more noise because of all the local interference.

Simply walking around your house with a portable will often yield a good sweet spot. That's also a good start.

Also with lower end portables like the 750 and G8, an external antenna will easily overload the radio. I don't have this problem with the G6 and G5.

Andreas, how does that loop antenna do with higher frequencies like in the 15000khz range?

Andreas

Shawn, my personal design is different from that shown in the link. I use an active loop. Let me relate: years ago I built an active antenna with preselection and a whip straight from a kit. It was o.k., but not really great. So I made one little modification... I didn't change anything in the circuit but one simple thing: I replaced the coil of the L/C input stage by a loop of about 35 cm diameter only! The loop ist simple made from copper wire. You can vary the MHz-range by changing the numbers of windings, e.g. for the 60m band I use 3 or 4 windings. On lower bands I sometimes even use a ferrite with a couple of windings.

This homebrew works great for me on all lower bands approx. up to 7 MHz. On the bands above I'm not really "at home", so I can't answer your question faithfully.

And you are absolutely right: there's not one "true" antenna! Therefore antenna experiments are always promising!

Andreas

A very cheap and nevertheless promising preselector-design to boost your telescope antenna:

http://www.dobe.com/wts/funk/preslctr.txt

(Micheal, this design will NOT work with your ATS-803a, but with many other modern time receivers that lack a built-in preselector.)

This simple design provides great improvement e.g. with my RP-2100 on all shortwave bands I use.

Michael Salmons

Shawn, I would never think to walk around the house with a radio to check things out. Thanks for that tip.

Andreas, thanks once again for the thoughtful input. This preselector looks like great little project. Perfect for a weekend.

Andreas

Yes, Michael, and if you need more information, ask Google for "ADDX-Pre-1". (ADDX is the german shortwave listeners association, that made this preselector very popular in europe.)

PS. Many users report, that especially the Sony ICF-2010 (ICF-2001D) benefits a lot from this preselector!

Keith Beesley

Michael,

The bands most affected by local RFI (radio frequency interference) at my house are the longwave band (150-500 kHZ), the lower shortwave bands (c. 2-4 mHz) i.e. tropical bands, and to some extent the AM (MW) broadcast band. Try turning off all computers, modems, TVs, fluorescent lamps, etc., or get as far away from them as possible. Also it goes without saying, battery operation is better than AC! Less noise from the house wiring. You can use rechargeables.

Good luck!

Angelo

I'm being serious about this. If you have the space, pick up an old console stereo from the 1970's---Zenith, RCA, any good quality furniture style stereo. You can and probably will ignore the built in 8 track player and turntable---if those don't work, you probably won't care, and someone might even pay you to take the console out of their house (if you don't have a pick-up truck, rent one from Home Depot and grab a couple friends to help you move it---then treat them to lunch). Anyway, with your knowledge of antennas, you can get something on your roof and feed it through the walls to hook up to the console. You'll get great reception (our 1973-74 RCA was amazing WITHOUT an added antenna) and the speakers will blow your socks off.

Michael Salmons

Keith, RFI probably explains a lot of the problems I experience. Our house is also old so maybe the shielding is a factor? I have no idea, I know only enough about house wiring to get in trouble.

Angelo, are we now talking FM? I've never seen a console stereo with SW.

Though you bring up an interesting point. Frequently I an filled with desire for a beautiful old tabletop made by Saba or Grundig. Only my lack of dealing with electronics of that age have kept me from accumulating those as well!

Shawn Patrick

Yea,

Shortwave antenna building and trial and error is almost as much of an obsession as the radio itself with a lot of shortwave listeners. It's a big topic also with ham radio operators, always trying to build the ultimate antenna.

I tried building a homemade loop AM antenna using a capacitor of an old radio... I never could get it to work but I blame my poor building skills.

Amazingly are some of the antennas that are built and posted on the web. Youtube has dozens of videos featuring shortwave antenna and construction.

Part of the fun is experimenting around. If I had more land and wasn't so uncoordinated, I would put more effort into mine.

So for now, I just use a random length of speakwire spread across my yard.

Cheers.

Brian (Scooby214)

I have made a strong AM loop antenna by modifying the detector tank on one of my crystal radio sets. This particular set has a single tuned detector tank with a large 175/46 Litz ferrite coil. The coil is coupled to a 380 pf air variable capacitor, and tunes the entire AM BC band. I inductively couple it to small radios such as the Grundig G8 or Kchibo D96L, and it really helps with daytime AM DX reception. It is of less help with my larger portables such as the Panasonic RF-888, probably due to the fact that the 888 has a very good antenna to start with.

Andreas

Brian, brilliant concept! Building a loop antenna is very often limited by our mechanical skills. So it's a good idea to start with ready to use components from other radios.

Tim

I built a 24 inch AM loop antenna for the broadcast band using the calculator on this page, and it works great:
http://www.angelfire.com/mb/amandx/loop.html
Total cost about $25.

Chris

I built a basic tuner once using a variable capacitor for tuning, then to a potentiometer for being able to roll back the amount of signal from the antenna, and it worked well. Coax from the antenna to the tuner, then I just used a jumper of bell wire and 'gator clips to the radio.

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