Posted: 12/30/2012 12:43:06 PM EDT
| Well, HF anyway. Took the 817 and some wires up on a local mountain, sat up there for a couple hours on 20 and 40 meters. Heard lotsa people, didn't make a contact. I know, QRP. Had a wire cut for 20 at a half wavelength and 40 at a quarter. Both let me listen to anything on either band, I used the banana plug connection as recommended by W0ZF on his youtube channel. Any opinions on that setup? For now I'm fairly happy. Talking to someone would have been nice, but at least I got out and used the radio. |
| You need a "counterpoise" (ground wire) for the antenna to function properly. The counterpoise should be the same length as the radiator (wire connected to the center of coax connector). Otherwise the SWR will be so high the rig will limit output power severly. I bet you didn't have .1 watt output with what you were using. |
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Quoted:
So if I put a wire the same length on the ground connector of the radio and lay it out, output will be better? Yes. A counterpoise or ground plane is critical for the radio to operate. You technically had one -- and it was you (and the microphone cord, most likely.) Neither you nor the microphone cord are terribly efficient grounds, so you should see a pretty good improvement. Also I've found orienting the antenna wire vertically rather than horizontally helps a bunch. I did measurements using the WSPR mode, and saw a +12 to +15 db improvement with a vertical wire v. a low horizontal wire. |
| build THIS but instead of the 15ft ground radials build 4 33ft ones and enjoy. |
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Quoted: So if I put a wire the same length on the ground connector of the radio and lay it out, output will be better? The radiating element of an antenna needs something to 'push against'. This is where a counterpoise comes into the picture. A dipole antenna radiates from one side while the other side acts as a counterpoise. A loop antenna cut for the band you are operating needs no counterpoise, however many times performs better with one. Just make sure that when you transmit, your SWR is less than 3:1 or you run the risk of letting the mAJiCk sMoKE out of your radio. It's a bitch to get that stuffed back inside. |
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actually for 40m you probably want radials about 21ft (IIRC) long. Radials on the ground are much shorter than the free space length due to dielectric effect of the ground. If you were trying to run a "half wave" end fed element on 20m with no tuning you were trying to transmit into a near infinite impedance. The simplest antennas, you need either a 1/4 wave element over a ground plane, or else a dipole with 1/4 wave on each side for the band you are trying to use. Also, hopefully you know that ground elevation is not particularly important for HF communications, with regards to your trip up into the mountains. I'm sure you had a nice quiet location with little RF noise or interference though, might be why you were hearing a lot of stuff even with less than ideal antennas. |
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make a dipole
http://www.arrl.org/files/file/Technology/tis/info/pdf/9106023.pdf beg borrow or steal an SWR meter and trim until you have low SWR call CQ on the QRP freq's |
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If you are going to use just a wire you really need a "random wire antenna tuner."
This thing is great for portable use and can tune a random wire as well. (it also has an swr meter on the tuner so with just one wire, or dipole you can tune most of the HF band.) http://www.mfjenterprises.com/Product.php?productid=MFJ-971 |
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Quoted: If you are going to use just a wire you really need a "random wire antenna tuner." This thing is great for portable use and can tune a random wire as well. (it also has an swr meter on the tuner so with just one wire, or dipole you can tune most of the HF band.) http://www.mfjenterprises.com/Product.php?productid=MFJ-971 You still need a counterpoise. |
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Quoted:
If you are going to use just a wire you really need a "random wire antenna tuner." This thing is great for portable use and can tune a random wire as well. (it also has an swr meter on the tuner so with just one wire, or dipole you can tune most of the HF band.) http://www.mfjenterprises.com/Product.php?productid=MFJ-971 A Hendricks 40m - 15m SOTA Halfwave Tuner (kit) would be another good alternative. A half-wave antenna with a counterpoise is much more efficient than a quarter-wave antenna with a counterpoise. Quarter-wave antennas need a number of radials to be efficient. ETA: Were you using SSB or CW? 5 watts of SSB is roughly equivalent to 200 milliwatts of CW, while 5 watts of CW is roughly equivalent to 125 watts of SSB. 
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