Posted: 1/26/2012 3:13:24 PM EDT
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The recent thread TN2T on 12 Meters got me scrambling for the radio, even though I was about 4 hours too late. Anyway, I decided I'd try some grayline on 10. However, instead of tuning up like I'd usually do, I decided to see what would happen if I bypassed the tuner. Recently I added some 10 meter legs to my OCF Windom and, sure enough, SWR was acceptable, staying with 1.3:1 for USB at about 100 watts (FM killed the radio, of course). So I decided to try out other bands. I was able to make my way down to 80 meters and only hit 3:1 at worst. I just can't understand how my radio can be so agreeable with a Windom wrapped around the rafters on so many bands. I understand 10 meters, and 12 meters doesn't seem to far of a stretch, on the 10 meter legs. The antenna is cut for 40 meters, so that's understanable, and, to a degree, 15 meters. I know it's best to tune, but I can't see 1.5:1 or better overall to be that bad, except for long-winded QSOs. |
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If you have low SWR everywhere, it's usually a sign that you've got some big losses someplace.
An extreme example is a dummy load, it's a perfect match and radiates no signal. (Well, except for KB7DX on WSPR, his dummy load works there.) Another example would be something like a terminated folded dipole, which basically dumps the unradiated RF into a big resistor. It has low SWR and is very broadband, and also pretty much sucks for transmitting on most bands. A resonant antenna should absolutely have big SWR peaks and valleys –– if you're not seeing them, then you're probably having issues with either detuning or feedline. However, it could just be you're looking at the SWR on the right bands, too. Based on this plot for an OCF windom, I'd say check SWR on 30M and 17M and see if it's way high. If you're not seeing unacceptably high SWR on those bands, you've got some losses someplace that need fixin'. |
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Quoted: If you have low SWR everywhere, it's usually a sign that you've got some big losses someplace. An extreme example is a dummy load, it's a perfect match and radiates no signal. (Well, except for KB7DX on WSPR, his dummy load works there.) Another example would be something like a terminated folded dipole, which basically dumps the unradiated RF into a big resistor. It has low SWR and is very broadband, and also pretty much sucks for transmitting on most bands. A resonant antenna should absolutely have big SWR peaks and valleys –– if you're not seeing them, then you're probably having issues with either detuning or feedline. However, it could just be you're looking at the SWR on the right bands, too. Based on this plot for an OCF windom, I'd say check SWR on 30M and 17M and see if it's way high. If you're not seeing unacceptably high SWR on those bands, you've got some losses someplace that need fixin'. Is there a way to test on 30 without a keyer or digital interface? |
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Quoted: If you have low SWR everywhere, it's usually a sign that you've got some big losses someplace. An extreme example is a dummy load, it's a perfect match and radiates no signal. (Well, except for KB7DX on WSPR, his dummy load works there.) Another example would be something like a terminated folded dipole, which basically dumps the unradiated RF into a big resistor. It has low SWR and is very broadband, and also pretty much sucks for transmitting on most bands. A resonant antenna should absolutely have big SWR peaks and valleys –– if you're not seeing them, then you're probably having issues with either detuning or feedline. However, it could just be you're looking at the SWR on the right bands, too. Based on this plot for an OCF windom, I'd say check SWR on 30M and 17M and see if it's way high. If you're not seeing unacceptably high SWR on those bands, you've got some losses someplace that need fixin'. Just tested several frequencies on 17 and pushed it to infinity. I guess I was too soft spoken on my first go 'round. |
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Quoted: [rimshot]If you have low SWR everywhere, it's usually a sign that you've got some big losses someplace. An extreme example is a dummy load, it's a perfect match and radiates no signal. (Well, except for KB7DX on WSPR, his dummy load works there.) Another example would be something like a terminated folded dipole, which basically dumps the unradiated RF into a big resistor. It has low SWR and is very broadband, and also pretty much sucks for transmitting on most bands. A resonant antenna should absolutely have big SWR peaks and valleys –– if you're not seeing them, then you're probably having issues with either detuning or feedline. However, it could just be you're looking at the SWR on the right bands, too. Based on this plot for an OCF windom, I'd say check SWR on 30M and 17M and see if it's way high. If you're not seeing unacceptably high SWR on those bands, you've got some losses someplace that need fixin'. He said something about that. LOL!!!
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Quoted:
Quoted:
If you have low SWR everywhere, it's usually a sign that you've got some big losses someplace. An extreme example is a dummy load, it's a perfect match and radiates no signal. (Well, except for KB7DX on WSPR, his dummy load works there.) Another example would be something like a terminated folded dipole, which basically dumps the unradiated RF into a big resistor. It has low SWR and is very broadband, and also pretty much sucks for transmitting on most bands. A resonant antenna should absolutely have big SWR peaks and valleys –– if you're not seeing them, then you're probably having issues with either detuning or feedline. However, it could just be you're looking at the SWR on the right bands, too. Based on this plot for an OCF windom, I'd say check SWR on 30M and 17M and see if it's way high. If you're not seeing unacceptably high SWR on those bands, you've got some losses someplace that need fixin'. Just tested several frequencies on 17 and pushed it to infinity. I guess I was too soft spoken on my first go 'round. OK, then you're good. And as far as 30M... switch to AM and be very quiet when you key the mic. |
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Quoted:
Quoted:
If you have low SWR everywhere, it's usually a sign that you've got some big losses someplace. An extreme example is a dummy load, it's a perfect match and radiates no signal. (Well, except for KB7DX on WSPR, his dummy load works there.) Another example would be something like a terminated folded dipole, which basically dumps the unradiated RF into a big resistor. It has low SWR and is very broadband, and also pretty much sucks for transmitting on most bands. A resonant antenna should absolutely have big SWR peaks and valleys –– if you're not seeing them, then you're probably having issues with either detuning or feedline. However, it could just be you're looking at the SWR on the right bands, too. Based on this plot for an OCF windom, I'd say check SWR on 30M and 17M and see if it's way high. If you're not seeing unacceptably high SWR on those bands, you've got some losses someplace that need fixin'. Is there a way to test on 30 without a keyer or digital interface? An unmodulated AM carrier will work. P.S. They do call my dummyload a "Cantenna". 
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Quoted: So, what balun and what are the lengths of the short and long legs of your OCFD? Balun is 4:1 (not sure of type, Gigaparts calls it a BiFi). Overall length is ~66ft, not sure of leg lengths. Given that most are 2/3 and 1/3, I'd say 22ft and 44ft, but I have a feeling the ratio is a little closer. |