HFU HF Underground
Technical Topics => Equipment => Topic started by: MDK2 on May 14, 2016, 2035 UTC
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... for a long wire or random wire being used for reception only? I see some out there (like the MFJ 16010) but they appear to be geared mostly for transmitting.
Just throwing it out there. I don't really have any purpose for one unless I know it could help improve reception, but I'm not sure how that would help. My radios already have tuners after all.
Thank you.
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Short answer:
Maybe.
Long answer:
The purpose of an antenna tuner is to match the impedance of the antenna to the radio. Maximum power transfer occurs when the impedances are the same. As you've noted, this is very important for transmitting, as you want to maximize the actual radiated power. Plus, many modern transmitters will automatically reduce the output power when feeding into a large mismatch, to prevent damage. With receivers, it's a slightly different situation. There's no risk of damage with a mismatch. But it's still sometimes useful to match impedances, to get the most signal out of your antenna. I personally don't use an antenna tuner now, but many years ago, when I was more serious into long wave, I did use a homemade tuner, and noticed tremendous improvement. In that case I was listening with about a 200 ft longwire, which was extremely short (capacitive) on the longwave band. That was probably a worst case situation. About the same time, I was also using a tuner on shortwave, and while as I recall I did provide a small increase in the signal strength, it was not substantial. And it was a pain to continuously adjust the tuner when changing bands or even frequencies.
Another [positive] side effect of using a tuner is that it also often acts as a filter, rejecting stations from other bands. This can be extremely useful if your radio is overloading, say from a nearby AM station. Although in that case, a simple fixed high pass filter that blocks MW would suffice.
You can certainly try a tuner, and see if you notice much of an improvement. I would not count on a major improvement, however, in most cases.
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Short answer:
Maybe.
Long answer:
The purpose of an antenna tuner is to match the impedance of the antenna to the radio. Maximum power transfer occurs when the impedances are the same. As you've noted, this is very important for transmitting, as you want to maximize the actual radiated power. Plus, many modern transmitters will automatically reduce the output power when feeding into a large mismatch, to prevent damage. With receivers, it's a slightly different situation. There's no risk of damage with a mismatch. But it's still sometimes useful to match impedances, to get the most signal out of your antenna. I personally don't use an antenna tuner now, but many years ago, when I was more serious into long wave, I did use a homemade tuner, and noticed tremendous improvement. In that case I was listening with about a 200 ft longwire, which was extremely short (capacitive) on the longwave band. That was probably a worst case situation. About the same time, I was also using a tuner on shortwave, and while as I recall I did provide a small increase in the signal strength, it was not substantial. And it was a pain to continuously adjust the tuner when changing bands or even frequencies.
Another [positive] side effect of using a tuner is that it also often acts as a filter, rejecting stations from other bands. This can be extremely useful if your radio is overloading, say from a nearby AM station. Although in that case, a simple fixed high pass filter that blocks MW would suffice.
You can certainly try a tuner, and see if you notice much of an improvement. I would not count on a major improvement, however, in most cases.
Well, I do live in the city and local MW signals do make the lower HF bands all but pointless for me, at least on my current receiver. That "fixed high pass filter that blocks MW" sounds intriguing however. Although I might just need a balun or something too. As I mentioned elsewhere the longwire goes straight into the 750. Or maybe just a different antenna. Things to ponder... Thanks Chris.
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Chris, you may want to make your answer a sticky, it comes up so often.
JC
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They definitely increase the number of knobs in your shack. That's always a plus in todays world of SDR's and other faux radios.
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I've been using that same tuner for years with my Yaesu FRG-100 hooked up to a 110' longwire. In my case it definitely works, as it gives me numerous options (settings) to help pull in the weaker signals. I attached the longwire to the rear jack of the tuner using a banana-type plug (I think that's what you call it).
I hope that helps..
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Thanks everyone. I did pick up a MFJ 16010-ST * on eBay for pretty cheap, and I think it has helped improve my reception a bit, at least as far as using it as a choke goes. I have also begun to hear stations I haven't before, despite the poor propagation conditions we have had recently. I'm not sure how much credit the tuner deserves for it because I've also been listening in at different times and to different frequency bands than before, thanks to summertime changes to my schedule allowing me more time for SWLing and DX'ing.
@ OhFiveCharlie, I have done just as you said, gotten a banana plug for the longwire. Seems to work just fine.
* This is an old tuner that does not resemble the current MFJ 16010. It looks exactly like the MFJ 902 or 902b. I don't know if the internal adjustable components are identical to the 902 or 902b, but the circuitry must be otherwise the same.
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^ I purchased mine over 10yrs ago, so I'm not sure it's the current one. I got mine brand new on Fleabay also. I figured it would be safe to do being it's an MFJ (Mighty Fine Junk) product and if it didn't work, I can always throw it off my terrace lol..
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On my current hf antenna (ocf dipole) I use a B&W lowpass filter to keep the fm broadcast and vhf sigs out of the front end of the hf rig and a old Grove TUN3 minituner to selectively peak frequencies when desired. The TUN3 is best at the lower freqs, higher freqs and it's of little value. However, it does provide for a more efficient transfer of energy from the antenna system to the receiver, and a tuner, any tuner, should accomplish the same. They are a benefit if used correctly. I modded the TUN3 to have a gas discharge dealy to help keep nearby lightning strikes from harming the rig, and set it to the grounded input position when not in use.