Home |
Search |
Today's Posts |
|
#1
|
|||
|
|||
Balcony Antenna for Shortwave Listening
Hello,
On Tue, 07 Dec 2010 21:58:17 -0800, Richard Clark wrote: On 08 Dec 2010 00:45:41 GMT, SĂ©bastien MEDARD wrote: But, before that I just wanted to know what would be a good antenna, or good antennas for where I live. want to listen to. You should have a choke (W2DU style BalUn) connected at the feedpoint. One example shown at: http://www.n0ss.net/qrp_1-1_w2du_coaxial_balun.pdf That's the first thing I will do. Ferrite ordered Paying attention to your ground is important, but if you live upstairs in an apartment, then think dipole (even if one side is vertical - where the horizontal wire would be called a "long-wire"). OK. By the way...... What would be a good antenna tuner for a SWL? Any advice for a brand? Any advice for a good DIY kit? The price you could pay is not a predictor of performance. Look at the schematic on the last page of: http://www.mfjenterprises.com/man/pdf/MFJ-902.pdf Seems not so simple for me. I see two things on the schematic : - 2 variable capcitor and an inductance on the center - A balun for balanced line (ie dipole????) As I already get a balun for dipole could you confirm that I just need the center part of the schematic? If the answer is yes, if I understand the schematic well, both of variable capacitors are put one after the other inserted into the line. The big question is how to make the variable inductance? Some wire wired on a ferrite rod? (L ----------- A????) with a selector? Are the number of half-loops means the number of turns? Even there, with a good switching design you could use the same components to build them too. (I am thinking of PI configuration, L, and so on). What is the influence of these different configurations? Old AM (tube) radio parts are perfect for building your own tuner. It seems I need to find some Thank you for your patience, Sebastien. |
#2
|
|||
|
|||
Balcony Antenna for Shortwave Listening
On 09 Dec 2010 17:11:54 GMT, Sébastien MEDARD wrote:
http://www.n0ss.net/qrp_1-1_w2du_coaxial_balun.pdf That's the first thing I will do. Ferrite ordered Hi Sébastien, Good first step. http://www.mfjenterprises.com/man/pdf/MFJ-902.pdf Seems not so simple for me. I see two things on the schematic : - 2 variable capcitor and an inductance on the center Good. - A balun for balanced line (ie dipole????) Yes. As I already get a balun for dipole could you confirm that I just need the center part of the schematic? Confirmed, yes. If the answer is yes, if I understand the schematic well, both of variable capacitors are put one after the other inserted into the line. The big question is how to make the variable inductance? Some wire wired on a ferrite rod? (L ----------- A????) with a selector? Are the number of half-loops means the number of turns? Making the coil is easy. It is just bare wire. You connect leads between various turns in the coil and a switch. A three to five position switch will work. You can even wind separate coils and put them on the switch so they add up in series as you turn the switch. Even there, with a good switching design you could use the same components to build them too. (I am thinking of PI configuration, L, and so on). What is the influence of these different configurations? Some antennas (I am speaking of their wavelength, not style like horizontal, vertical, end-fed, or other) are easier to tune with these other styles, but the style offered in the link is fairly general purpose. Old AM (tube) radio parts are perfect for building your own tuner. It seems I need to find some It may not be easy, but if you can find the right shop, you will find many. Tell the shop owner you want this for experimentation and you might get something that isn't in the shop display. The only thing you really need is the variable capacitor from two radios. This technology was very common and found in nearly every home in the 1950s and 60s, but now would be rare unless you find that shop. Thank you for your patience, Feel free to ask more questions when it comes time to put this together. 73's Richard Clark, KB7QHC |
#3
|
|||
|
|||
Balcony Antenna for Shortwave Listening
On Thu, 09 Dec 2010 11:33:27 -0800, Richard Clark wrote:
If the answer is yes, if I understand the schematic well, both of variable capacitors are put one after the other inserted into the line. The big question is how to make the variable inductance? Some wire wired on a ferrite rod? (L ----------- A????) with a selector? Are the number of half-loops means the number of turns? Making the coil is easy. It is just bare wire. You connect leads between various turns in the coil and a switch. A three to five position switch will work. You can even wind separate coils and put them on the switch so they add up in series as you turn the switch. OK. Even there, with a good switching design you could use the same components to build them too. (I am thinking of PI configuration, L, and so on). What is the influence of these different configurations? Some antennas (I am speaking of their wavelength, not style like horizontal, vertical, end-fed, or other) are easier to tune with these other styles, but the style offered in the link is fairly general purpose. I found a PI network tuner shematic. Many thanks for the first steps help! SĂ©bastien. |
Reply |
Thread Tools | Search this Thread |
Display Modes | |
|
|