Shortwave Antenna

[davidmc36]

I Have an old HF unit that I want to set up for receiving Shortwave. I have a kit from Radio Shack that I got at surplus. It is the 278-758. It has 70ft of antenna wire and 50ft of lead in wire.

My question is would there be any advantage to swapping out the insulated lead in wire for coax? If so, what would you use?

The reciever goes from 1.6 to 23 mhz. Obviously there will be no one ideal length to use if I have no antenna tuner, but I could not use the tuner that it normally uses becaues without the proper license to transmit, I could not activate the tuner. I suppose you could not activate the tuner either if it is only hooked up to that type of antenna. The antenna wire is 20ga and the lead in wire is about 22 or 24ga. I should be able to get a manual tuner for it though, correct?, and just do it by "feel"?

 

[kb2vxa]

Don't worry about a tuner, you don't need one. Don't need coax either, just use the antenna and lead in wire as shown in the instructions. For general coverage shortwave listening you don't need any extras, lots of us do very well with simple receivers and simple antennas.

 

[davidmc36]

How long would you make it? The full 70ft that is in the kit will be 1/4wave for about 6.6mhz and 1/2wave for about 3.3mhz. That will be closer to the lower end of the radio's band.

I actually have two kits and easily enough room on my property to use all of it.

 

[WouffHong]

SW Antenna

I Have an old HF unit that I want to set up for receiving Shortwave. I have a kit from Radio Shack that I got at surplus. It is the 278-758. It has 70ft of antenna wire and 50ft of lead in wire.

My question is would there be any advantage to swapping out the insulated lead in wire for coax? If so, what would you use?

The reciever goes from 1.6 to 23 mhz. Obviously there will be no one ideal length to use if I have no antenna tuner, but I could not use the tuner that it normally uses becaues without the proper license to transmit, I could not activate the tuner. I suppose you could not activate the tuner either if it is only hooked up to that type of antenna. The antenna wire is 20ga and the lead in wire is about 22 or 24ga. I should be able to get a manual tuner for it though, correct?, and just do it by "feel"?

Coupla points you might consider..

To keep nearby shack or home interference down a bit, consider getting some 50 or 75 ohm coax (such as good old cable-TV 75-ohm cable) and an inexpensive Antenna Tuner (an MFJ or other brand) and you will find that by tweaking the Tuner by "ear", the received signals will peak at some setting that you can write down for future listening at that frequency.

You might try running the antenna from a tree using the 70' on the center conductor of the coax and the 50' chunk connected to the shield of the coax and either hanging down or run to another tie point - You can use a piece of plastic with a few holes drilled in it as an insulator. Waterproof the coax and wire junction with some insulating putty, or electrical tape (But that usually leaks and unwinds in the weather and water can get into the Coax)

REMEMBER to have some way to disconnect the coax when lightning is around!!

Grounding the receiver may also suppress some noise and improve reception BUT: assuming it's an older, tube receiver, there should be a Ground lug, screw or bolt on the receiver rear- check with an AC meter that there is no AC voltage between there and some local ground before using it and/or connecting the Receiver ground lug to the local true ground. One can have a shocking experience with older receivers..

That's kinda a collection of general thoughts, and may be appropriate for your situation if an older receiver. :roll:

Bottom Line: Safety First!

73

Tom

 

[davidmc36]

You can use a piece of plastic with a few holes drilled in it as an insulator. Waterproof the coax and wire junction with some insulating putty, or electrical tape (But that usually leaks and unwinds in the weather and water can get into the Coax)

My kit should make that setup nicely. It comes with two plastic "eggs" for the ends of the bare copper part and a couple of nail on insulators for down the side of the house or whatever.

Grounding the receiver may also suppress some noise and improve reception BUT: assuming it's an older, tube receiver, there should be a Ground lug,

No tubes in the reciever but it does have a big ass grounding lug. It already has a bonding wire from the HF to the power supply. Do you think that would provide a good ground? The plug that feeds house current to the power supply is a three lug with ground and then the bonding wire goes from the power supply to the HF. That is how it was set up where I got it from.

Thanks for all the great info.

 

[W6KRU]

How long would you make it? The full 70ft that is in the kit will be 1/4wave for about 6.6mhz and 1/2wave for about 3.3mhz. That will be closer to the lower end of the radio's band.

I actually have two kits and easily enough room on my property to use all of it.

Sorta. It would be 1/8 wave for 3.3. You should put up the most wire you can within reason. 70' on each side of the dipole will be in the 3.5 mHz neighborhood.

 

[davidmc36]

How long would you make it? The full 70ft that is in the kit will be 1/4wave for about 6.6mhz and 1/2wave for about 3.3mhz. That will be closer to the lower end of the radio's band.

I actually have two kits and easily enough room on my property to use all of it.

Sorta. It would be 1/8 wave for 3.3. You should put up the most wire you can within reason. 70' on each side of the dipole will be in the 3.5 mHz neighborhood.

Oops! I got that backwards. I used this calculator:

http://www.qsl.net/kd4sai/antencal.html

It tells me that 70ft is 1/2wave for 6.6mhz and 1/4wave for 3.3mhz. The plans with the kit show connecting the insulated feed line to the end of the antenna wire. Would you say that a dipole with the feed line in the center would be a better antenna overall?

 

[W6KRU]

Oops! I got that backwards. I used this calculator:

http://www.qsl.net/kd4sai/antencal.html

It tells me that 70ft is 1/2wave for 6.6mhz and 1/4wave for 3.3mhz. The plans with the kit show connecting the insulated feed line to the end of the antenna wire. Would you say that a dipole with the feed line in the center would be a better antenna overall?

That is the way I would do it. A dipole with 1/4 wavelength per side for the lowest frequency you want to listen to.

 

[prcguy]

Getting the antenna outside and away from RF noise in your house is a good idea but feeding a dipole with coax for continuous operation over the frequency range of your receiver is not. I vote for making the longest dipole you can fit on your property fed with 300 ohm TV twinlead or450 ohm ladder line right to the receiver. This will get the antenna away from noise sources and the balanced line will reject noise on the way to the receiver and all but ignore high VSWR between the antenna and feedline.
prcguy

 

[davidmc36]

Some great ideas guys. I may have to try more than one. Can't wait to start pullin' in the BBC. lol

 

[OceanaRadio]

David,

With the 70' RS wire kit strung out in any direction and at any elevation (higher angles work better), you will have access to a lot more than broadcast, which is receivable from an indoor telescoping whip. Utility stations (aeronautical, maritime, military, etc) can be pulled in from your entire hemisphere and beyond in winter months. As Warren suggested, don't both with adding a tuner since only expensive ones have a bypass switch and without that you are forced to find a tune-match for every frequency you try to listen to. More work than it's worth. And no you cannot use the xmtr-set's built-in tuner, even if you obtain a license, except for the ham bands you are licensed in. The RS antenna kit used to come with a window-lead that allows a window to close over the lead. Of course as another reader warned, this sets you up to forget to diconnect the antenna before a storm someday. Be careful there.

Is that a King Charles Spaniel in your avian/pic?

Jack

 

[davidmc36]

David,

With the 70' RS wire kit strung out in any direction and at any elevation (higher angles work better), you will have access to a lot more than broadcast, which is receivable from an indoor telescoping whip. Utility stations (aeronautical, maritime, military, etc) can be pulled in from your entire hemisphere and beyond in winter months. As Warren suggested, don't both with adding a tuner since only expensive ones have a bypass switch and without that you are forced to find a tune-match for every frequency you try to listen to. More work than it's worth. And no you cannot use the xmtr-set's built-in tuner, even if you obtain a license, except for the ham bands you are licensed in. The RS antenna kit used to come with a window-lead that allows a window to close over the lead. Of course as another reader warned, this sets you up to forget to diconnect the antenna before a storm someday. Be careful there.

Is that a King Charles Spaniel in your avian/pic?

Jack

That is most definitely a Cavalier in the pic, Alfie is just one year old.

I believe somebody pointed out before that there is no "Ham" license for what this unit transmits on, only restrcited radio operators license, and I am not an airplane or a base that has any business on those bands. Is that correct or is there some of the freqs in the 1.6-23mhz that are Ham bands?

There is a window lead in like you mention, I got two kits a while ago "just in case" that were new in the package. I am thinking that I should set up something easier to disconnect. I don't mind drilling another hole in the house, there are already about a dozen coaxes coming in.

Thanks for the additional tips.

 

[OceanaRadio]

Beautiful dog!

Yes 90% of the amateur frequencies fall between 1.8 and 29 MHz. If your radio is a marine transceiver, it will only transmit on marine-bands, which are a smaller part of that spectrum. Unless of course it was "opened" to TX on all MF/HF frequencies, a possibility, depending on who/what previously owned it. In any case it should receive on all MF/HF bands and that is what you are interested in.

Getting a wire up is the first part, you can always add wire and make improvements later.

Jack

 

[davidmc36]

Beautiful dog!

Yes 90% of the amateur frequencies fall between 1.8 and 29 MHz. If your radio is a marine transceiver, it will only transmit on marine-bands, which are a smaller part of that spectrum. Unless of course it was "opened" to TX on all MF/HF frequencies, a possibility, depending on who/what previously owned it. In any case it should receive on all MF/HF bands and that is what you are interested in.

Getting a wire up is the first part, you can always add wire and make improvements later.

Jack

I found the manual on-line but have not set down to read it yet. I know there is a sequence of buttons that you press to program a total of 48 pre-sets into it but I never looked at just what freqs are available. At any rate I would need the Advanced License with Code to use anything below 29 I think. Is that correct? Something for a future goal once I get started with the Basic.

Alfie is quite a handful at times but great company for the Missus since I work out of town on three week rotations.

Cheers

 

[davidmc36]

I found the manual on-line but have not set down to read it yet. I know there is a sequence of buttons that you press to program a total of 48 pre-sets into it but I never looked at just what freqs are available. At any rate I would need the Advanced License with Code to use anything below 29 I think. Is that correct? Something for a future goal once I get started with the Basic.

Alfie is quite a handful at times but great company for the Missus since I work out of town on three week rotations.

Cheers

As expected, took a browse through the manual and comared it to a freq allocation chart. It only transmits on the fixed and mobile maritime and radiotelephone freqs. It will be lots of fun listening though since it will recieve seamlessly from 1.6 to 23. I can learn a lot about how it is done and someday get a new rig and try it out. I am still looking forward to getting a dual band VHF/UHF and joining the airwaves.