TheRadioBoard

wireguy · Joined: 11 Feb 2007 Posts: 216 Location: Indiana

I now live very close to two local am stations. My attempt at traps and tuners has failed. What I have on hand: One ceramic (cardwell?) vari-cap about 34 plates, one ceramic Bud 100mmfdmidget condenser(NOS), one tapped broadcast band (NOS) coil. These were used in earlier attempts at tuners. I want to put up a better antenna this spring. I only have a 25 foot wire up now. Any ideas on getting past these two locals? I am only interested recieving BCB. The only thing that has worked is my four foot looper.
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J.B. Weazle McCreath · Posted: Sun Jan 31, 2010 12:45 pm Post subject:

Hi wireguy,

How much bigger will your new antenna be? If you can somehow manage
to put up more than 100 feet of wire you could use a series tuner and link
couple it to your set. This eliminates the direct connection of the antenna
to the sets tank circuit, plus it gives you some selectivity improvement
that can go a long way to cutting out loud locals.

Cheers, J.B., VE3EAR
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To be where I am, I had to leave where I was!

wireguy · Joined: 11 Feb 2007 Posts: 216 Location: Indiana

I plan on 120 feet. I live in town. Our house is big, surounded by big homes. Lots of power lines. I will probably buy a comercial grade antenna. Is there not a good universal tuner available?
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What would our world be like, if Tesla was alive in our time?

J.B. Weazle McCreath · Posted: Sun Jan 31, 2010 3:35 pm Post subject:

wireguy,

Buy an antenna?? That goes against everything I hold sacred. For use on
a xtal set, we're just talking about a non-resonant length of wire, a couple
of insulators, and maybe a feedthru, depending on how you get it inside.
Nothing high-tech required and all the makings can be had at any good
hardware or farm supply store very cheaply.

For the tuner, all that's required is a variable cap and a coil similar to the
ones you're using in your set. Connect the lead-in from the antenna to
one end of the coil, the other end of the coil to the capacitor stator,
and the cap frame/rotor to your ground.

Align the coil of the tuner with the coil of the set and away you go!
Playing with the spacing between the coils and their alignment is
how the coupling is varied. Close for tight gives loudest at the cost
of selectivity, while apart for loose yields a drop in loudness but the
selectivity improves. It's the selectivity that will get rid of your two
local "crocodile" stations (all mouth, no ears).

Cheers, J.B.
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To be where I am, I had to leave where I was!

wireguy · Joined: 11 Feb 2007 Posts: 216 Location: Indiana

OK, I will try another. The coil I used before was a NOS BCB coil with 8 taps. I would be better of winding a staight coil with no taps?
_________________
What would our world be like, if Tesla was alive in our time?

J.B. Weazle McCreath · Posted: Mon Feb 01, 2010 3:37 am Post subject:

I'll assume that the varicap you have for the tuner is similar to the one that
is in your set. If that's the case, wind a new coil for the tuner that has 10
to 20% more turns than your sets coil. It's easier to remove turns than to
add them if you find it necessary to tweak the coil.

Cheers, J.B., VE3EAR
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To be where I am, I had to leave where I was!

old voltmeter · Joined: 02 Jan 2010 Posts: 29 Location: Uncertain, Texas

Wireguy: I have to agree with J.B. DON'T go out and buy a antenna. I just hung a 130 foot inverted L. Cost less than $5.00 wire was the biggest cost. Look around you proibly have all you need close at hand.

I have two flamethrowers in my backyard KEEL and sister Station KWKH both 50,000 watter less than 10 miles across water from my QTH. What I did was to make a wave trap that took care of KWKH it was the greatest offender. With the longer antenna and wave trap a simple radio nothing great I am reciving DX. This morning I pick up WLS, WHO, And KCMO. The band was full and couldn't get all but will work tonight to pick up more.

I am going to constructed a tuggle front end for this radio which is like a tuner. I think that with a good antenna and a wave trap that you will be suprised what is out there on your radio.

DON'T get discouraged I knew that there was a sloution to my problem and there is a solution to yours. Try a antenna tuner they are simple to make. Then try a trap they are just as easy to make. Look on Owen Poole's web site I just copied his. Breadboarded to a cardboard box. It works great!!!! You have two varicaps and that is all you need..

I am very new to this building crystal sets. Build my first one since I was like 8 years old less than a month ago. now I have a set that will pick up stations that are 1000 miles from my QTH not armchair copy but still got them. All I have right now for phones is a simple crystal earpiece. Put on a pair of shooters muff and you will be suprised what you can hear.

Best of luck there are alot of guys here that will help that is why they are here to exchange ideas and help us newbies.

Best of 73's

Stan
Uncertain, Texas