New Antenna! But does it work better?

[beamin]

So I live in a basement apt. thats 1/2 way under ground. Makes the grounding part very easy. So this is what I created:

GROUND
A 24" copper pipe that has stripped wire spooled around the top then wrapped in electrical tape. From this a 18ga wire comes in through my window where it goes into a short 6" piece of rg6? cable left by the comcast people. Its connected to the shielding.

ANT
The center copper wire of the cable is connected to a roughly 30' length of stranded 18 ga wire that runs horizontally along the ceiling.

So here is what I heard the 5000kHz Canada tine signal comes in very good at night. All signals seem louder and on some bands the noise is ALSO louder. But on 5MHz and 27MHz (quarter and full wave length for this size ant. I think?) The noise is lower. At 27MHz something weird happens almost no static or 60MHz harmonics but a strange almost 10or 20 Hz buzz sound comes out: This happens on other bands too but not as bad. Picked up some distant CB signals but here in Baltimore MD not many use a CB. Almost none of the hiss static at 27MHz.

Is this a feature (the buzz) of running a full wave length? Seems this antenna really needs the ground to work; the wire by itself seems to only work a little better then no antenna. Why? Is it over loading this radio? Just a few really hard and vague no simple answer questions I have.

 

[ka3jjz]

Well let's start with the 5000 Khz signal - that's WWV in Fort Collins, Co. CHU - the Canadian time station - is on other frequencies.

The 'buzz' is not related to having a 'full wave length'. It's hard to say what this buzz is that you are hearing around 27 Mhz. There are many lo-power devices that work in that range - cordless mice being one. There is also a possibility of picking up noise from a wall wart, which have next to no shielding on them, and would also cause noise on other freqs besides 27 Mhz.

RFI issues are often difficult to isolate, particularly since you can't necessarily turn off everything in your building to find the cause. You can try turning off your own electricity, but if it's being radiated from outside your unit, there's little in the way of remediation you can do to the offender.

Mike

 

[wyShack]

the length of your antenna(in wavelengths)should make no difference on hum pickup. If you think of your antenna, receiver tuner and ground system as forming a 'circuit', you may have just 'hit' a frequency where other noise is 'tuned' out allowing your receiver to hear what is actually broadband noise. Most of today's receivers are actually more sensitive than they need to be with the 'noise level' driving the AGC (automatic gain control(s)) to lower sensitivity. often the overall antenna 'circuit' has many points where it has 'peaks' and 'dips(or nulls) caused by the complex impedance interacting with the receiver 'front end'.

I would recommend that you 'tie' your ground rod to the main ground rod for your building. This will reduce some of the noise, and also protect your equipment. nearby lightning (like out to a mile) and 'faults' on the power system in your area can cause 'local' ground potentials to differ by many volts (for sort terms and under rare conditions many hundred) which can easily damage the tuner in your receiver.

Have fun experimenting with the new antenna

73

 

[popnokick]

So I live in a basement apt. thats 1/2 way under ground. Makes the grounding part very easy. So this is what I created:

GROUND
A 24" copper pipe that has stripped wire spooled around the top then wrapped in electrical tape. From this a 18ga wire comes in through my window where it goes into a short 6" piece of rg6? cable left by the comcast people. Its connected to the shielding.

ANT
The center copper wire of the cable is connected to a roughly 30' length of stranded 18 ga wire that runs horizontally along the ceiling.

Do you mean to say that the 30 foot length of antenna wire runs along the ceiling of your BASEMENT apartment? If so, that means that there is very likely electrical wiring directly above your antenna wire (in the floor of the apartments above you... and notice I wrote "apartments" plural)? Every one of those apartments and all of their wiring is generating RFI / EMI which will get into an HF shortwave receiver. And if your building has foil-backed insulation in the walls, it will make the problem worse. I'm encouraged to read you can receive WWV on 5 mHz, but is there any way you can get any wire outside of the building?

 

[beamin]

Do you mean to say that the 30 foot length of antenna wire runs along the ceiling of your BASEMENT apartment? If so, that means that there is very likely electrical wiring directly above your antenna wire (in the floor of the apartments above you... and notice I wrote "apartments" plural)? Every one of those apartments and all of their wiring is generating RFI / EMI which will get into an HF shortwave receiver. And if your building has foil-backed insulation in the walls, it will make the problem worse. I'm encouraged to read you can receive WWV on 5 mHz, but is there any way you can get any wire outside of the building?

The wire hangs one foot from the ceiling as far away from any walls with any mains conductors. I factored this in when I was laying out the cable, also it's away from the upstairs neighbors wifi and refrigerator (I have been inside their house). Np foil backed insulation, built at a time before.

Wouldn't tying it into the mains ground just pick up tons of noise? I tried that as a lazy way to make a ground and found that out. I appreciate the info about lightning but I also factored that in and I disconnect the power and ant/gnd cable when I'm not using it. We do have pretty bad lightning some summers in MD and global warming is making it worse.

I can run the wire to a tree about 5' off the ground out side but the wire will go up to the tree at 45' angle from ground level then take 90' right turn to the next tree with a gain of 25' feet of wire above ground. Bad part is I can't leave the wire up when the grass cutters come.

 

[wyShack]

It is not just lightning that can cause a problem with multiple grounds-I would suggest you google 'ground potential rise'. Usually bonding the two grounds will eliminate the problem. I would suspect your noise pickup trying to use the main ground was either using the 'ground' at an outlet or running a wire to the other ground rod. at RF the impedance of a wire is terrible. I have gotten much better results by running a coax cable to the rod and putting a .01 microfarad capacitor between the center and shield at both ends of the coax. Use the building grounding system for for everything but RF.

I would not trade safety for better reception-it is not a good trade.

73

 

[WA8ZTZ]

Couple of suggestions:
look into building a loop or broomstick antenna... lots of plans out there for these, hard to say which would work better for you, you'll have to experiment

try some sort of tuner or preselector (such as the MFJ 956), it will allow you to peak the signal and tune out some of the noise