Wire Antenna Query

[rocky28965]

I have a basic understanding of antennas but the theory side of it is over my head.
I have a Tecsun PL-660 on order & my intention is to setup a temporary long wire antenna.
I will be aiming at frequencies between 3 & 17MHz.
Because of limited space it will be restricted to about 16M (50ft)
It would be 16 AWG insulated braded wire & run approximately East West.
One end attached to neighbors’ carport & terminate on my house roof.
Then approximately 5 M of RG58 or similar, into my man cave.
Question:
Should I have some sort of device (UnUn, Balum or Transformer) between the receiver & antenna?

Following this, as a project I would like to build a magnetic loop antenna to replace the long wire.
I have looked at loads of variations on the net & read through the wiki etc.
However my limited knowledge means I would have to follow someone else design & hope it does what I want.
But the variation of design & components make it difficult to decide which one to use.
I have attached a couple below which look simple enough for me to build.
Your comments or advice would be appreciated

Thanks

https://www.youtube.com/watch?v=ehjKrJ-TH_w

http://www.kr1st.com/swlloop.htm

 

[w2xq]

RR member https://www.radioreference.com/apps/user/majoco can probably best advise you on HF reception in your country. You can drop him a private message in case he doesn't immediately see this thread. No doubt you will hear many signals from east Asia. A general rule of thumb is too long an external random wire could overload a portable radio's front end. On the other hand, if you are in an electrically low noise environment a loop antenna may not be particularly beneficial... but it would be an interesting learning excercise. I'll leave it to other members to comment on HF loop construction and a balun for the PL-660, as I have no experience with either venture. There are numerous threads discussing the PL-660 and similar Tecsun portables, if you haven't seen them already. Good luck. HTH a bit.

 

[ka3jjz]

You probably don't want to go too much longer than 50 foot, altho it's a bit short to be efficient on 3 Mhz. If you still find overloading to be an issue, then take a look at this thread...

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

It gives you a bit of flexibility since you have a variable gain control (rather than a 3 position switch which might be either too much or too little). If the diodes should blow, you don't have to dig inside the radio and/or send it in somewhere.

The loop you have linked to is manually tuned; while it will work indoors, outdoor antennas are far preferable to get them away from noise sources in the home. Our loops wiki has many other designs - and quite a few homebrew types - here...

Loops - The RadioReference Wiki

Mike

 

[n5rv]

I'd leave yourself open to keeping as many antennas up and ready since not only the antenna performance that you are dealing with, there is also the band propagation at anytime into your area from other regions. I have 2 antenna for my Icom IC-R75, an Alpha Delta DX-Ultra and a 250 foot longwire that is in a horizontal U configuration. The DX-Ultra is a mult-band parallel dipole at 25 feet or so, and the longwire is about 10 feet off the ground. The long wire is great for AM BCB thru about 8MHz, the DX-Ultra is great for 6MHz and up. Having the overlap is nice and the signal strengths vary on antenna performance and propagation into my area. If you do build a mag-loop that will be great for directivity and nulling out co-channel interference, but due to size, you maybe only get the best performance from 7 to 17MHz..... building one for the lower frequencies is a challenge because the optimum size is rather large. But certainly doable. Building antennas is the best way to learn about them.... I am a lover of wire antennas since they are so easy to make and deploy.

73 de jerry N5RV

 

[majoco]

Without a transformer on the end of a coax fed wire, the capacitance of the cable sucks out some of your signal. Having said that, I don't think the antenna socket on the small portables is made to present a low impedance to match the coax any way - it's probably more designed to be fed from the small hank of wire that they supply with the radio. Certainly I have an un-un on my off-centre fed dipole as that feeds coax to a 50ohm input multicoupler and it works reasonably well - but in your case I would be tempted to try a 'no coax' first - just lead an insulated wire down to your radio but beware of too much signal - especially from local broadcast stations. If you wanted to improve on that you could try an antenna tuner at the radio but that's liable to cost more than the radio itself. There's often a receive-only Yaesu FRT-7700 or it's Kenwood equivalent on TradeMe for about $100.

 

[rocky28965]

Without a transformer on the end of a coax fed wire, the capacitance of the cable sucks out some of your signal. Having said that, I don't think the antenna socket on the small portables is made to present a low impedance to match the coax any way - it's probably more designed to be fed from the small hank of wire that they supply with the radio. Certainly I have an un-un on my off-centre fed dipole as that feeds coax to a 50ohm input multicoupler and it works reasonably well - but in your case I would be tempted to try a 'no coax' first - just lead an insulated wire down to your radio but beware of too much signal - especially from local broadcast stations. If you wanted to improve on that you could try an antenna tuner at the radio but that's liable to cost more than the radio itself. There's often a receive-only Yaesu FRT-7700 or it's Kenwood equivalent on TradeMe for about $100.

I'll try it like that & see how it goes.
At some point it will have to enter the roof & drop down inside a wall.
Won't that pickup interference from the house?

 

[ka3jjz]

Yes that's quite possible. Personally I would build a 9:1 so-called magnetic longwire balun and feed the antenna with coax to cut down on that possibility. There are numerous plans on the web and there are a few commercial units, too.

Mike

 

[rocky28965]

Thanks I'll keep that in mind.
I'm afraid my hands aren't up to making anything fiddly like that any more, I would have to buy one.
I assume this is the type of thing you are referring to:

https://www.ebay.com.au/sch/i.html?_nkw=9:1+balun&ul_noapp=true

 

[ka3jjz]

That's the general idea, yes altho I'd be rather careful about buying anything from fleaBay. Even better would be to use what a lot of folks use as a starter - the well known EF-SWL antenna. Scroll down this page to read about it...

https://www.lnrprecision.com/endfedz/

Using coax with your 660 you might need to make a pigtail of some kind to connect to the radio, but it should work just fine. Most of the portables today can handle a very wide range of impedances. The big brother to your radio, the 880, has several users that have the EF-SWL and it works fine.

In fact if you use the starter project I gave the link to you earlier, the input to the box would be a SO-239, then a phono plug out. That's a win win because you can disconnect the antenna from the box during lightning storms and leave the box connected.

Mike

 

[majoco]

I made up a short lead with a BNC female on one end to a standard mono 2.5mm plug to feed my Degen or. Tecsun

 

[krokus]

When hooking up an external, here is something to think about:

http://forums.radioreference.com/showthread.php?p=2390995

Sent using Tapatalk

 

[rocky28965]

I think I'll wait for the unit to arrive before I make any more decisions.

 

[rocky28965]

My PL-660 has arrived & I am very pleased with it.
Son will staying for a few days over Xmas so will nab him to assist with putting up the longwire.
If I get up a ladder these days my knees start to wobble.
I bought 20M of light grey insulated wire, hoping it will blend in, as it will be right in front.
Was looking round for some fishing gut for insulators & finished up buying 50M of 200LB stuff.
This is translucent & almost invisible when you hold it up against the sky.
So then I got the idea, maybe I could set the antenna up so it could be wound back in when not in use, by using the fishing line & some pulleys.
Was wondering if anyone else had used this method or if it was a bad idea for some reason.

 

[krokus]

... maybe I could set the antenna up so it could be wound back in when not in use, by using the fishing line & some pulleys.
Was wondering if anyone else had used this method or if it was a bad idea for some reason.

If you are going to do this, use a very flexible, stranded wire. This could lead to a strength concern.

 

[rocky28965]

I think I'll put it up temporarily first & see if it's going to worth the effort before I worry about winding it up.

 

[rocky28965]

Merry Xmas to all you guys.
We have got the antenna up in place.
I didn't know just what to expect from it.
I set the antenna gain switch on the 660 to normal & connected it via a mono audio adapter.
Reception was certainly stronger than with the wip antenna, but is picking up a pulsing interference from something.
I first though it might have been my wifi, but have now eliminated that.
However the neighbour's wireless internet receiver is about 3 meters from the far end of the antenna.
So are wondering if it may be that.
He is currently away atm so can't eliminate that.
To get it further away I would either have to shorten my antenna or change the angle of it.
I will get on to that but are tied up with family stuff atm.
Had a fairly warm one yesterday.
Had to close everything up at four oclock & crank up the aircon.