Another antenna question

[pinkfish457]

I'm using Ham-It-Up, a SDR dongle, and HDSDR software to listen to shortwave radio. My antenna is a 30 foot long wire connected to the center wire of RG6 coax with runs into my house. The wire is suspended on metal poles with porcelain insulators on each end. The outer braid is not connected to the antenna, only at the input of the upconverter. The upconverter is in a metal housing.

I'm getting lots of static and hissing noise on some of the frequencies. I tried making adjustments in HDSDR, but it doesn't help. Would using a balun help reduce the noise?

I also have a multi-band antenna which I run through the same RG6. When I want to use the VHF, I connect/reconnect the coax. There is no noise problems when using the multi-band antenna.

Thanks
pinkfish457

 

[Blackswan73]

Welcome to shortwave. The hissing and pops are normal on shortwave. VHF is usually FM, which usually don't have hissing and popping.

 

[ka3jjz]

It would be a bit tough to say what the hissing and popping would be about for sure, but the popping might be a sign of a poor solder job on the antenna somewhere. The hissing could be generated from the PC itself, or any number of other possibilities. Unfortunately this is the nature of the beast.

The popping could be any number of things, besides the poor solder joints.

One other thing that could cause the hissing is that the gain is set too high in HDSDR and you're overdriving the dongle. I don't have a SDR so I'm little help there - someone here could likely help with that, though.

Clearly a better antenna is in order. What are your conditions? How much space have you got to work with? How about any trees? Are there power lines near the antenna - If so, can it fall on the lines (which could easily cause a deadly situation)? .

Mike

 

[ridgescan]

You have no counterpoise/RF ground. Try to find a groundpoint somewhere close (3-6') to the coax braid and ground the braid. This may improve noise.

 

[Blackswan73]

Also noise level depends on what band you are listening to. Generally in the daytime, the higher bands are quieter, 11 MHz. and . At night, the powers bands are usually quieter, below 12mhz.

 

[pinkfish457]

Another Question

I found a Grove Power-ANT III in my junk box, and connected it to my long-wire antenna. It seems to cancel most of the noise.

Is the Power-Ant the same as a UnUn or is it an antenna tuner?

 

[ka3jjz]

After looking it up on Google, this is nothing more than a preamp with a variable gain control. Usually preamps add more noise than signal, but hey, as long as it works for you, go for it. Just keep that gain control down so you don't overdrive your receiver...Mike

 

[db_gain]

Some things to try are adding ferrite cores to the feed line at the antenna and radio ends of the coax, and adjusting the filter passband in hdsdr, ferrites will keep radio frequency noises from traveling along the outside of the coax, and the hdsdr filter bandwidth can tailor the audio to the signal, as well as enabling noise reduction if desired. Also, hdsdr has a effective noise blanker, wich reduces the pops and static to a degree.

 

[k9wkj]

keep the preamp gain down to the bottom
keep the dongle gain just about on the bottom