TECSUN PL 990 X Antenna Question

[dipoledummy]

I would like to experiment with various length dipole( twin lead) wire antennas on shortwave. Does the antenna jack of the 990 support this or is it only a single downlead ?

I like to experiment with various length dipole ( twin lead ) wire antennas on the shortwave bands. Will the antenna jack of the Tecsun 990x support this or is it only a single downlead?

 

[iMONITOR]

There is a lot of discussion on the 990 and antennas here:

Tecsun PL-990 – The SWLing Post

swling.com

 

[ka3jjz]

That article talks about loops, not wire antennas....

Hmmm...a nominal impedance for a dipole, mounted at the correct height, is roughly 50-75 ohms. A twin lead dipole can work with a balun, depending on what design you are using. Then the coax comes from the balun down into the radio. Like many portables, I would try to avoid putting a lot of stress on that jack. They're usually flimsy; a pigtail might be the best bet here.

If you just feed it with twin lead, you are close to creating an old 'T' type antenna - in this case, just twist the two wires together and lightly solder them for stability..;..

Need more info here, I think....Mike

 

[dipoledummy]

That article talks about loops, not wire antennas....

Hmmm...a nominal impedance for a dipole, mounted at the correct height, is roughly 50-75 ohms. A twin lead dipole can work with a balun, depending on what design you are using. Then the coax comes from the balun down into the radio. Like many portables, I would try to avoid putting a lot of stress on that jack. They're usually flimsy; a pigtail might be the best bet here.

If you just feed it with twin lead, you are close to creating an old 'T' type antenna - in this case, just twist the two wires together and lightly solder them for stability..;..

Need more info here, I think....Mike

My plans were to use 50-100 feet of light gauge speaker wire suspended between 2 trees. I f it makes no difference then I will probably solder both leads to an alligator clip and fasten the clip to the unextended whip antenna

 

[dipoledummy]

My original plans for this antenna, based on unfounded assumptions was if I made a dipole wire antenna for 80 meters and fed it into the receiver via the antenna jack that it would work best on 80 meters and be directional in nature. My second assumption this same antenna with both downleads clipped to the telescoping antenna would work on the entire HF band and be non-directional. That was why I asked about the antenna jack - hope we have some Tecsun experts out there

 

[iMONITOR]

My plans were to use 50-100 feet of light gauge speaker wire suspended between 2 trees. I f it makes no difference then I will probably solder both leads to an alligator clip and fasten the clip to the unextended whip antenna

You'll probably end up blowing out the front end, the telescope antenna input is very sensitive.

 

[ka3jjz]

A couple of things here;

• Yes, a full size 80 meter dipole would likely be way too much for a portable without some control on the gain. Overloading (nee 'blowing out') is a very likely result. Too, an 80 meter dipole will work best on the frequency for which it's cut, and on the third harmonic. So if it was cut for 3.5 Mhz, it would next be resonant on 10.5 Mhz. For receiving, it's probably not all that important, but once you move off the designed frequency, the directional pattern will change
• There are a couple of ways to address this; one would be to add a passive preselector (like the MFJ 1046) between the antenna and radio. Another far less expensive way is to add a potentiometer between the 2. This thread discusses static drain, and the schematic shows the pot... Static drain for outside long wire antenna
• NEVER connect anything directly to the whip unless there's no other way. One static zap from the antenna, and the amp (likely at the base of the whip or nearby) will blow, rendering the radio deaf. Use the antenna jack - it likely has some diodes there anyway to prevent static damage.
• There are many, much smaller antenna designs that would likely work well, although many are not necessarily directional. Read topic 5 of Basic HF Antennas - The RadioReference Wiki

Mike