Antenna tuners are expensive!

[joeuser]

Hi, with the help of the community brain trust. I have decided on going with dipole " G5RV " variation. I'm going to be using a Realistic DX-440 & possibly another older receiver down the road (older as in no digital read out). After much reading & discussion its also clear that even though I'm just listening & not transmitting I really must have an antenna tuner. WOW, they ain't cheap! Seeing them around 200$.

I assume the automatic tuners only work with the transmitted signal not the received only.

I have seen ' kits ' on eBay from HK for 15 bucks. They are so cheap it scares me. I also am weary of " you get what you pay for " Are these kits viable?

I was going to go with MFJ but man alive, some of the reviews really concern me... MFJ standing for Mostly Fracking Junk? (Something like that).

So now I'm looking at used on eBay... I saw a cool old Heathkit for 144$ & I watched it - I had a feeling it was a good deal & while I was researching it, the darn thing sold! I should have just jumped on it, but I'm a total noob at this...

I've seen some name brand stuff, home made deals, etc... Im hoping for general pointers without having to pawn off a kidney...

 

[mitbr]

Hi, with the help of the community brain trust. I have decided on going with dipole " G5RV " variation. I'm going to be using a Realistic DX-440 & possibly another older receiver down the road (older as in no digital read out). After much reading & discussion its also clear that even though I'm just listening & not transmitting I really must have an antenna tuner. WOW, they ain't cheap! Seeing them around 200$.

I assume the automatic tuners only work with the transmitted signal not the received only.

I have seen ' kits ' on eBay from HK for 15 bucks. They are so cheap it scares me. I also am weary of " you get what you pay for " Are these kits viable?

I was going to go with MFJ but man alive, some of the reviews really concern me... MFJ standing for Mostly Fracking Junk? (Something like that).

So now I'm looking at used on eBay... I saw a cool old Heathkit for 144$ & I watched it - I had a feeling it was a good deal & while I was researching it, the darn thing sold! I should have just jumped on it, but I'm a total noob at this...

I've seen some name brand stuff, home made deals, etc... Im hoping for general pointers without having to pawn off a kidney...

An antenna tuner is used primarily to match a transmission line to the radio when you transmit.
It can have an effect on reception if the antenna is poorly ,matched to the frequency you are listening to.

You cannot use an automatic ant tuner unless you transmit.

The G5RV is not a great swl antenna as it is tuned for the ham bands only.

I would save the money needed for a tuner and put it into the antenna.
If you need any more help let me know I have been a ham for 20 years and make my own wire antennas.


Tim

 

[popnokick]

You're only receiving, right? A tuner can be added to a receive-only G5RV anytime, so try it WITHOUT a tuner first and if you're not satisfied, buy and install one then. Be sure you have an adapter to use the Ext Antenna jack on the radio. And beware that you may overload the receiver's front end when using the external antenna. You may need an attenuator... I can't see that the DX440 has one built in. A tuner might help in this regard, as you could deliberately detune slightly to reduce the incoming signal level. An MFJ-901B is $100 and can do the RX-only job. And yes... auto tuners are used with transmitters.

 

[prcguy]

A G5RV is sort of tuned to the 20m amateur band, otherwise its a random length dipole fed with balanced line and they work fantastic for SWL without a tuner. The thing that makes it work so well for SWL is the almost loss-less balanced feedline that doesn't incur extra loss working in a high VSWR environment like coax does.

You don't specifically need a G5RV and you can simply make a dipole almost any (large) size to fit your property and run balanced line all the way to the radio. If your radio has a coax connector use a 1:1 choke balun close to the radio with the least amount of coax possible and you will have a SW antenna that rocks.
prcguy

An antenna tuner is used primarily to match a transmission line to the radio when you transmit.
It can have an effect on reception if the antenna is poorly ,matched to the frequency you are listening to.

You cannot use an automatic ant tuner unless you transmit.

The G5RV is not a great swl antenna as it is tuned for the ham bands only.

I would save the money needed for a tuner and put it into the antenna.
If you need any more help let me know I have been a ham for 20 years and make my own wire antennas.


Tim

 

[prcguy]

Forgot to mention, some tuners are not that expensive. If your really want an HF tuner look for a Dentron Jr tuner on Fleabay. These are great little tuners that work the entire HF band and they usually go for less than $50 used. They also handle up to 300w if you ever need to transmit.

If you put up a G5RV or similar dipole fed with balanced line you really don't need a tuner. You will find you can peak the signal some with a tuner but the signal to noise ratio, which is what determines how well you receive, will not be improved with a tuner when using a large antenna like a G5RV. You can get the signal level to come up some but the noise will come up the same amount and your signal to noise ratio will not change.

If your using a really small antenna (short whip, etc) without a large capture area and its starving the receiver for signal, then an antenna tuner can actually improve reception by bringing up the signal above the noise.
prcguy

 

[n0nhp]

When using my G5RV for SWL (on my transceiver) I bypass the tuner. I have tried both ways and have found that it will make much less than one S unit of difference, it will sometimes help reduce background noise or in some cases increase background noise when the antenna is "tuned". As others have said, the only reason for the tuner is to present a "tuned" load to the transmitter. The G5RV is a very good, low noise SWL antenna and due to it's balanced nature resists man made noise that end fed and random wire antennas often exhibit.
Make sure you have a switch or other disconnect for the antenna though. It will build static in windy and under thunderstorm conditions. Older and lower cost receivers do not have the front-end protection that some of the high end equipment has. I replaced the FET front end on a lot of Sony and other low cost SWL receivers due to the owners putting up an outside antenna and forgetting to disconnect it when they were done listening.

Bruce

 

[ka3jjz]

<snip>Make sure you have a switch or other disconnect for the antenna though. It will build static in windy and under thunderstorm conditions. Older and lower cost receivers do not have the front-end protection that some of the high end equipment has. I replaced the FET front end on a lot of Sony and other low cost SWL receivers due to the owners putting up an outside antenna and forgetting to disconnect it when they were done listening.

Bruce

That is the exact reason for this little first-timer project I mentioned in this thread...

http://forums.radioreference.com/receive-antennas-below-30mhz/295299-great-first-timer-project.html

Better to blow some cheap diodes in a box....Mike

 

[joeuser]

OK. I think I finally have my ducks in a row now! Now its time to shop!

Thank you so much gentlemen! Not just here... but all the other HAM threads I had questions skillfully, thoughtfully, & forgivingly answered. Really appreciate it.

 

[Boombox]

My take on it is that you probably don't need a tuner. And if you want a tuner, get a used MFJ. It's very hard for a company to mess up something so simple as an antenna tuner.

A DX-440 has plenty of gain, and although they say the G5RV is tuned for 20 meters (I'm just going by what they say, I don't know much about G5RV's), it should also pick up SW broadcasts from lower frequencies also.

If the DX-440 happens to overload, you can turn down the RF gain. I used to run mine into a 100 ft wire and didn't notice any overload effects, but I'm in a low signal area.

I'd be more concerned about static electricity from the outdoor antenna zapping the 440's RF transistor, either during winter when the outdoor air is dry, or due to nearby thunderstorms..

It might be a good idea to run a pair of diodes 'back to back' (parallel, reversed polarity from each other) between the antennas hot side and the ground, especially during winter.

 

[joeuser]

My take on it is that you probably don't need a tuner. And if you want a tuner, get a used MFJ. It's very hard for a company to mess up something so simple as an antenna tuner.

A DX-440 has plenty of gain, and although they say the G5RV is tuned for 20 meters (I'm just going by what they say, I don't know much about G5RV's), it should also pick up SW broadcasts from lower frequencies also.

If the DX-440 happens to overload, you can turn down the RF gain. I used to run mine into a 100 ft wire and didn't notice any overload effects, but I'm in a low signal area.

I'd be more concerned about static electricity from the outdoor antenna zapping the 440's RF transistor, either during winter when the outdoor air is dry, or due to nearby thunderstorms..

It might be a good idea to run a pair of diodes 'back to back' (parallel, reversed polarity from each other) between the antennas hot side and the ground, especially during winter.

Won't the static discharge into the ground? I was either going to run a line to the cold water pipe or drive a stake into the ground...

 

[teufler]

either are a good ground. I second the choice a dentron jr. Though not automatic, you can tune the antenna for noise or louder volume. Then note your frequency and write the setting from the tuner down along with the frequency. Then if you switch to that approximate frequency again, you can dial the tuner and you will be in the ball park quickly. The bigger Dentron tuners, the 3000, the ads had that tuner loading the bedsprings on a bed and talking . I have loaded the chainlink fence, and it worked. MFJ , I have had a tuner made by them but I sold it. Nothing bad, just didn't need it.

 

[ka3jjz]

My take on it is that you probably don't need a tuner. And if you want a tuner, get a used MFJ. It's very hard for a company to mess up something so simple as an antenna tuner.

A DX-440 has plenty of gain, and although they say the G5RV is tuned for 20 meters (I'm just going by what they say, I don't know much about G5RV's), it should also pick up SW broadcasts from lower frequencies also.

If the DX-440 happens to overload, you can turn down the RF gain. I used to run mine into a 100 ft wire and didn't notice any overload effects, but I'm in a low signal area.

I'd be more concerned about static electricity from the outdoor antenna zapping the 440's RF transistor, either during winter when the outdoor air is dry, or due to nearby thunderstorms..

It might be a good idea to run a pair of diodes 'back to back' (parallel, reversed polarity from each other) between the antennas hot side and the ground, especially during winter.

While on the surface that sounds like a good idea, there's an issue here - if you live in a heavy RF saturated area, or have nearby MW/FM transmitters, there's a chance that the diodes could rectify and cause all sorts of noise or other issues. Better to use a gas-discharge tube - even a small neon light bulb will do the job. Mike

 

[Boombox]

Won't the static discharge into the ground? I was either going to run a line to the cold water pipe or drive a stake into the ground...

In a way, yes, but not the way you want it to.

Static electricity coming off the antenna during a dry, cold winter day or static charges from a nearby T-storm will flow through the antenna and then discharge to the ground through the radio's RF circuit (and the RF transistor is an FET -- sensitive to static charges) if you don't supply an alternate path to ground ahead of the radio (and the radio's RF circuits).

Either diodes, or like KA8JJZ says, a neon bulb running between the hot side and ground, would be a good investment to protect the DX-440's RF FET.

I think diodes would be an effective method -- many radios (like the DX-398 and DX-375) already have protection diodes wired in the antenna circuit. But if you can get a neon bulb, I've heard of them being used also, and it might even be simpler. You place the neon bulb or 'back to back' diodes between the antenna lead and your ground wire. Static charges will choose that path to the ground instead of trying to find its way through your radio's RF amp.

I had my 440 hooked up to my 100 ft. antenna for several years, with no damage. But I always unplugged it when not in use, and I live in an area with humid winters and very little thunderstorm activity. I also had my 440 wired with protection diodes inside the back of the case (between the antenna connection and the battery ground). During times I thought it was cold and dry enough for there to be static charges on the outdoor antenna I used an indoor antenna.

At the very least, be extra careful with your radio in winter if you live where the air gets cold and dry in winter (you live in Kansas, I think it gets dry there in winter?), and always unplug the antenna from the radio when not in use, and especially whenever there is t-storm activity present.

Hope this helps.

Chris

 

[joeuser]

In a way, yes, but not the way you want it to.

Static electricity coming off the antenna during a dry, cold winter day or static charges from a nearby T-storm will flow through the antenna and then discharge to the ground through the radio's RF circuit (and the RF transistor is an FET -- sensitive to static charges) if you don't supply an alternate path to ground ahead of the radio (and the radio's RF circuits).

Either diodes, or like KA8JJZ says, a neon bulb running between the hot side and ground, would be a good investment to protect the DX-440's RF FET.

I think diodes would be an effective method -- many radios (like the DX-398 and DX-375) already have protection diodes wired in the antenna circuit. But if you can get a neon bulb, I've heard of them being used also, and it might even be simpler. You place the neon bulb or 'back to back' diodes between the antenna lead and your ground wire. Static charges will choose that path to the ground instead of trying to find its way through your radio's RF amp.

I had my 440 hooked up to my 100 ft. antenna for several years, with no damage. But I always unplugged it when not in use, and I live in an area with humid winters and very little thunderstorm activity. I also had my 440 wired with protection diodes inside the back of the case (between the antenna connection and the battery ground). During times I thought it was cold and dry enough for there to be static charges on the outdoor antenna I used an indoor antenna.

At the very least, be extra careful with your radio in winter if you live where the air gets cold and dry in winter (you live in Kansas, I think it gets dry there in winter?), and always unplug the antenna from the radio when not in use, and especially whenever there is t-storm activity present.

Hope this helps.

Chris

OK, good advice. Yes, it gets dry in the Winter & we do have considerable T-Storms. So, I will have to deal with this. Its cheaper to buy this stuff than it is to buy radios!