Improving the fidelity of AM reception audio

[asynchronousman]

Originally Posted by Timbo in Oz

IMO&E PC's Modern TV's and anything else with a switch-mode PSU, will generate quiet a lot of RFI/EMI. which a meer intrenal antenna WILL pick up.

A random wire up highish outside, feeding into a 'low-noise' down lead - some fig 8. wire, or some 300 ohm TV ribbon, looped to stop rain entering yr home, and earthed to a real RF ground, will be a lot better than just the ferrite rod on the back.

if you add a tapped coil and a vane cap you can tune the wire so it 'thinks' it is from 600 metres to 200 or so metres long. this alolowers the bandwidth of the antenna system and lowers nosie even more, it also increases gain.

If the earth is accessible under the run of yr wire up in the air, you could run an in-ground radial back to earth of the same length as yr random wire.

Even an exterior remotely tuned loop, using a varactor, is possible, you put the loop made from rainbow/ribbon inside some EV stable pipe in circle and yr done, maaate.

Timbo

Aye, I've tried to do that and I've pondered putting those ferrite beads from the computer monitors cables, etc on the line to quell them. Maybe I should do that, because the monitor itself will put hash and birdies over everything below 30 meters (above 13 MHz for the rest of you) on my Hallicrafters S-118 Mk II (5-tube) receiver. I also live next to a substations and Heinz Frozen Food (Ore-Ida, the tater tot folks) as well as a cold storage plant and a truck stop. If you go downtown there a major feeder line that actually phases and brings 3 other stations in over two local region's frequencies!

Mother Nature can be a lot worse, though! I was undeneath a MAJOR storm cell for 15 miles once and the entire AM band SQUEALED and SCREECHED this ungodly, baleful and terrifying din. I though the radio had busted right then a there for 5 minutes until I switched to FM and it WORKED. Since it was my prize AM stereo Delco radio, I had thought it was ruined, but when I came back out of it, it returned to normal (major sigh of relief).

You, being in OZ don't have as many stations and they have better co-channel separation too.