HF Antennas - Experience/Knowledge Needed

Status
Not open for further replies.

ScubaJungle

Active Member
Premium Subscriber
Joined
Mar 11, 2020
Messages
620
Location
West Central Florida
Or......wait a month or three and get the new Icom IC-705. Its a small radio that has the same display as the IC-7300 and has HF, 2m and 70cm. With a 100w HF amp it should be very similar to the 7300 and you will have VHF and UHF. Add an LDG tuner and you will have up to 10:1 tuning range on HF instead of the more limited 3:1 of the internal 7300 tuner. The performance of the 705 should be similar to the 7300 and if worse, not much worse. IC-705 All Mode Portable - Features - Icom America
Hmm, that does look good, but to be honest I'm not big on early-adoption. The 7300 is looking real good, and I'm starting to get excited to have it!

Now I'm thinking about an antenna. Not sure if I should make a separate thread or not, but for now Ill keep it here
.
I like the idea of the doublet/dipole with ladder line, and the ones I've used on the spyserver have gotten really great reception.
Since I'm in limited space, I'm thinking of building a helical doublet with slinky and ladder line. I don't see any obvious reason why this wouldn't work, but is there anything I'm missing?
I figure if the G5RV "JR" is about 52ft, I can get that down to half and still get coverage up to 40m-60m

The design I was thinking of was:
Slinky - Slinky meet at center insulator, go to ladder line. Ladder line goes down to center insulator and into coax, coax starts with 6 spins for balun.

slinky Ctr ins. slinky
~~~~~~o~~~~~~~
||
|| ladder line
o ctr ins.
O coax - 6-turns
| coax

My biggest question about this is that I've seen specified lengths for the ladder line - is it necessary to have a specific length, and if so, can I also put that into a helical pattern for saving space?

I have a 8-10 foot balcony, so I really don't have much to work with and need to get creative. I can use the inside of my apartment, and I can go from balcony to window and get probably 20 feet total across outside, a bit more inside.
 

AK9R

Lead Wiki Manager
Super Moderator
Joined
Jul 18, 2004
Messages
6,667
Location
Central Indiana
Now I'm thinking about an antenna. Not sure if I should make a separate thread or not, but for now Ill keep it here
You've made a pretty clear and distinct change in topic. Yes, you should have started a new thread which I've done for you.
 

prcguy

Member
Joined
Jun 30, 2006
Messages
10,513
Location
So Cal - Richardson, TX - Tewksbury, MA
A G5RV is a 102ft long 20m antenna that happens to radiate ok 80 through 10m due to its size. A G5RV Jr would be a 51ft long 10m antenna that sort of works 40 through 10 and maybe 6m. When you say getting that down to half size are you starting with a Jr and then using the slinky to load it so it fits in maybe 20ft of space? If so be prepared for huge disappointment.

Antennas are all about size. As an example, half wave dipole has known and good performance and for 40m its about 64ft long. Cut that in half (32ft) with loading coils and its going to be noticeably worse with a much narrower band width and a serious impedance change. Cut that down in half again to 16ft with loading coils and it will just plain suck compared to the full size 1/2 wavelength. Just ask anyone who has made a 40m dipole out of a couple of Hamsticks. Now use cheap thin steel coil spring wire with huge IR loss at RF (like a slinky) to load its entire already compromised length and you might as well take up another hobby. At least in my opinion.

So you have maybe 20ft of space outside? I think you might have the best success with a loaded vertical and use as much of the balcony for counterpoise wire. How high could you go with a vertical? I know a few people using large screwdriver antennas with long whips on top and lots of counterpoise wires and they are making contacts. With a 500w amplifier they are maybe up to what other 100w stations are doing into a more efficient antenna, but at least they are on the air.

I've done an amount of hotel hopping on HF with varied success. The best was when I was able to toss about 50ft of wire out the window with a weight onto a roof next door and load that with a wire tuner against a combination hanging counterpoise and wires coming back into the hotel room. The wires heading into the room immediately picked up a lot of RF hash and interference even though they were grounded counterpoise wires, because they will conduct RFI right to the antenna and you will hear it in the receiver. Its best to not have any part of the antenna come indoors.

Another antenna that kind of worked was a 33ft telescoping fiberglass pole horizontal out the window with 32ft of wire on the pole and a counterpoise wire hanging straight down with a wire tuner at the window. Problem is you could see it from two blocks away sticking out over the sidewalk of the hotel but I figured it was temporary and I didn't care.

So thinking about what how big these antennas are and what they might of looked like, if you go smaller and closer to the building, the frustration level will go up exponentially trying to make contacts with a lousy antenna.


Hmm, that does look good, but to be honest I'm not big on early-adoption. The 7300 is looking real good, and I'm starting to get excited to have it!

Now I'm thinking about an antenna. Not sure if I should make a separate thread or not, but for now Ill keep it here
.
I like the idea of the doublet/dipole with ladder line, and the ones I've used on the spyserver have gotten really great reception.
Since I'm in limited space, I'm thinking of building a helical doublet with slinky and ladder line. I don't see any obvious reason why this wouldn't work, but is there anything I'm missing?
I figure if the G5RV "JR" is about 52ft, I can get that down to half and still get coverage up to 40m-60m

The design I was thinking of was:
Slinky - Slinky meet at center insulator, go to ladder line. Ladder line goes down to center insulator and into coax, coax starts with 6 spins for balun.

slinky Ctr ins. slinky
~~~~~~o~~~~~~~
||
|| ladder line
o ctr ins.
O coax - 6-turns
| coax

My biggest question about this is that I've seen specified lengths for the ladder line - is it necessary to have a specific length, and if so, can I also put that into a helical pattern for saving space?

I have a 8-10 foot balcony, so I really don't have much to work with and need to get creative. I can use the inside of my apartment, and I can go from balcony to window and get probably 20 feet total across outside, a bit more inside.
 

ScubaJungle

Active Member
Premium Subscriber
Joined
Mar 11, 2020
Messages
620
Location
West Central Florida
A G5RV is a 102ft long 20m antenna that happens to radiate ok 80 through 10m due to its size. A G5RV Jr would be a 51ft long 10m antenna that sort of works 40 through 10 and maybe 6m. When you say getting that down to half size are you starting with a Jr and then using the slinky to load it so it fits in maybe 20ft of space? If so be prepared for huge disappointment.

Antennas are all about size. As an example, half wave dipole has known and good performance and for 40m its about 64ft long. Cut that in half (32ft) with loading coils and its going to be noticeably worse with a much narrower band width and a serious impedance change. Cut that down in half again to 16ft with loading coils and it will just plain suck compared to the full size 1/2 wavelength. Just ask anyone who has made a 40m dipole out of a couple of Hamsticks. Now use cheap thin steel coil spring wire with huge IR loss at RF (like a slinky) to load its entire already compromised length and you might as well take up another hobby. At least in my opinion.

So you have maybe 20ft of space outside? I think you might have the best success with a loaded vertical and use as much of the balcony for counterpoise wire. How high could you go with a vertical? I know a few people using large screwdriver antennas with long whips on top and lots of counterpoise wires and they are making contacts. With a 500w amplifier they are maybe up to what other 100w stations are doing into a more efficient antenna, but at least they are on the air.

I've done an amount of hotel hopping on HF with varied success. The best was when I was able to toss about 50ft of wire out the window with a weight onto a roof next door and load that with a wire tuner against a combination hanging counterpoise and wires coming back into the hotel room. The wires heading into the room immediately picked up a lot of RF hash and interference even though they were grounded counterpoise wires, because they will conduct RFI right to the antenna and you will hear it in the receiver. Its best to not have any part of the antenna come indoors.

Another antenna that kind of worked was a 33ft telescoping fiberglass pole horizontal out the window with 32ft of wire on the pole and a counterpoise wire hanging straight down with a wire tuner at the window. Problem is you could see it from two blocks away sticking out over the sidewalk of the hotel but I figured it was temporary and I didn't care.

So thinking about what how big these antennas are and what they might of looked like, if you go smaller and closer to the building, the frustration level will go up exponentially trying to make contacts with a lousy antenna.
Thanks for the heads up, I was kind of thinking it had to be too good to be true.
I ended up getting one of the chameleon dipole antennas just so I can have an antenna that I know will work at first, and I can get to experimenting later on without having to rely on what I do make at first.

I'm going to see what I can do as far as space up, but I'm thinking I will just drop it down off my balcony at night.
Now instead of using an actual slinky, if I were to coil the dipole wires in a helical formation, would that be okay, possibly?
I'm going to have to do a lot of playing around. The loops I found were just too expensive so if I can get the chalemeon into a good spot, I'm hoping I'll be good. I get really good vhf and uhf coverage at my location with a dipole inside, and there's not as much noise as you would expect from a building, plus I'm the highest one within a mile or so, so there's nothing directly in the way.
If I can only get one wire extended, could I use the dipole as an end-fed with just one wire fully extended (and use the other as a couterpoise on the balcony), or would it not work like that?
 

prcguy

Member
Joined
Jun 30, 2006
Messages
10,513
Location
So Cal - Richardson, TX - Tewksbury, MA
Which Chameleon antenna did you get?


Thanks for the heads up, I was kind of thinking it had to be too good to be true.
I ended up getting one of the chameleon dipole antennas just so I can have an antenna that I know will work at first, and I can get to experimenting later on without having to rely on what I do make at first.

I'm going to see what I can do as far as space up, but I'm thinking I will just drop it down off my balcony at night.
Now instead of using an actual slinky, if I were to coil the dipole wires in a helical formation, would that be okay, possibly?
I'm going to have to do a lot of playing around. The loops I found were just too expensive so if I can get the chalemeon into a good spot, I'm hoping I'll be good. I get really good vhf and uhf coverage at my location with a dipole inside, and there's not as much noise as you would expect from a building, plus I'm the highest one within a mile or so, so there's nothing directly in the way.
If I can only get one wire extended, could I use the dipole as an end-fed with just one wire fully extended (and use the other as a couterpoise on the balcony), or would it not work like that?
 

ScubaJungle

Active Member
Premium Subscriber
Joined
Mar 11, 2020
Messages
620
Location
West Central Florida
I ended up going with that one^
It was between that and the end fed, both seem good but I figured the dipole may be a bit better
 

prcguy

Member
Joined
Jun 30, 2006
Messages
10,513
Location
So Cal - Richardson, TX - Tewksbury, MA
I have a couple of similar performing versions, the Chameleon CHA HYBRID-MINI and the CHA MPAS. I got the MPAS in a trade and was actually impressed with the quality and got the MINI just for the 500W rated transformer. Compared to my standard 40m EFHW and using the MINI as a 60ft end fed its about 1dB down on 40m and several dB down on 17 and 20m. Overall not that bad if you can get all 60ft of wire out in the clear.

I ended up going with that one^
It was between that and the end fed, both seem good but I figured the dipole may be a bit better
 

ScubaJungle

Active Member
Premium Subscriber
Joined
Mar 11, 2020
Messages
620
Location
West Central Florida
I have a couple of similar performing versions, the Chameleon CHA HYBRID-MINI and the CHA MPAS. I got the MPAS in a trade and was actually impressed with the quality and got the MINI just for the 500W rated transformer. Compared to my standard 40m EFHW and using the MINI as a 60ft end fed its about 1dB down on 40m and several dB down on 17 and 20m. Overall not that bad if you can get all 60ft of wire out in the clear.
I should be able to get 60 feet straight down.
I wonder if I should see if I can switch out the dipole for the end fed so I only have to worry about extending out one leg
 

prcguy

Member
Joined
Jun 30, 2006
Messages
10,513
Location
So Cal - Richardson, TX - Tewksbury, MA
Looks like your antenna must be used in a dipole mode at all times. They have different transformers like the HYBRID MINI and MICRO that are better suited for end fed use where you could have just the transformer, one wire and your coax with a good choke balun in the coax line.


I should be able to get 60 feet straight down.
I wonder if I should see if I can switch out the dipole for the end fed so I only have to worry about extending out one leg
 

W5lz

Active Member
Joined
Feb 28, 2019
Messages
588
It's a bit late for this, but can you drop a wire from your balcony to a tree/pole/whatever at your place? That would open up a few more options.
Just for information, that ladder line is part of the impedance matching that gets you to something around 50 ohms that your radio wants to see. It isn't an exact 'match' by any means (why a tuner is suggested for a G5RV), but it helps. It's length makes all the difference in what the impedance looks like on the radio end. Varying that length of ladder line can 'match' dang near any impedance. But think about that, it would be hugely inconvenient!
 

ScubaJungle

Active Member
Premium Subscriber
Joined
Mar 11, 2020
Messages
620
Location
West Central Florida
It's a bit late for this, but can you drop a wire from your balcony to a tree/pole/whatever at your place? That would open up a few more options.
Just for information, that ladder line is part of the impedance matching that gets you to something around 50 ohms that your radio wants to see. It isn't an exact 'match' by any means (why a tuner is suggested for a G5RV), but it helps. It's length makes all the difference in what the impedance looks like on the radio end. Varying that length of ladder line can 'match' dang near any impedance. But think about that, it would be hugely inconvenient!
I can drop it straight down when I'm using it - not really across though as there's a parking lot beneath me. I MAY be able to toss it up on the roof, but Im not sure if that will work, or if the roof will change the radiation pattern as I believe it may be some type of metal roofing.

My email to DXengineering never sent for replacing the dipole with the end-fed, so what I am going to do is wait for the dipole to come, see if I can get it to work in my space, and if not, replace it with the end fed. I also have a Palomar Engineers 9:1 transformer with end-fed coming, to have something to test it against. It was significantly cheaper, so I figured if I could have both to start out with, I could see what works and what doesn't. I may end up just switching the Chameleon dipole for the Chameleon end-fed unless the PE one is really good.
@prcguy - I saw you mentioned Palomar in a recent thread, do you have any input on their baluns/transformers?
 

prcguy

Member
Joined
Jun 30, 2006
Messages
10,513
Location
So Cal - Richardson, TX - Tewksbury, MA
Yes, I have input on Palomar products. I had a chat with Bob from Palomar Engineering at a friends hamster party a few years ago and asked him why he doesn't have anything that comes close to the MyAntennas common mode choke baluns. Sometime after that Palomar came out with a new series of tubular chokes (Maxi-Choker) with much better specs. In the end several of the MyAntennas chokes has better specs for less $$.

The Palomar Maxi-Choker is rated 500 to 5,000 ohms of choking resistance over the 1 to 61MHz range and one of the MyAntennas has 2,500 to 7,400 ohms choking resistance over the 160m to 6m bands. If you only need 160m through 10m another MyAntennas version has around 7,000 to 15,000 ohms choking resistance over those bands.

On the Chameleon antenna, the few products I own are well made and work ok. However, for an end fed type antenna you can't beat the resonant EFHW which is resonant on its intended bands and works much better than a 5:1 balun type like the Chameleon or its inferior competition, Alpha Antennas. The EFHW is also way superior to the 9:1 types. If you have room for an end fed with about 64ft of wire and would be happy with 40, 20, 15 and 10m, then a resonant EFHW will work great and usually without a tuner. To get 80m and the WARC bands you would have to go with an 80 through 10m version which is 133ft long, but they do work well and don't need a tuner on most bands.

@prcguy - I saw you mentioned Palomar in a recent thread, do you have any input on their baluns/transformers?
 

ScubaJungle

Active Member
Premium Subscriber
Joined
Mar 11, 2020
Messages
620
Location
West Central Florida
Yes, I have input on Palomar products. I had a chat with Bob from Palomar Engineering at a friends hamster party a few years ago and asked him why he doesn't have anything that comes close to the MyAntennas common mode choke baluns. Sometime after that Palomar came out with a new series of tubular chokes (Maxi-Choker) with much better specs. In the end several of the MyAntennas chokes has better specs for less $$.

The Palomar Maxi-Choker is rated 500 to 5,000 ohms of choking resistance over the 1 to 61MHz range and one of the MyAntennas has 2,500 to 7,400 ohms choking resistance over the 160m to 6m bands. If you only need 160m through 10m another MyAntennas version has around 7,000 to 15,000 ohms choking resistance over those bands.

On the Chameleon antenna, the few products I own are well made and work ok. However, for an end fed type antenna you can't beat the resonant EFHW which is resonant on its intended bands and works much better than a 5:1 balun type like the Chameleon or its inferior competition, Alpha Antennas. The EFHW is also way superior to the 9:1 types. If you have room for an end fed with about 64ft of wire and would be happy with 40, 20, 15 and 10m, then a resonant EFHW will work great and usually without a tuner. To get 80m and the WARC bands you would have to go with an 80 through 10m version which is 133ft long, but they do work well and don't need a tuner on most bands.
Cool, thanks. Hopefully, I am happy with these, but I would like to try an EFHW also. I may barely have enough room to drop 64ft if I mount it high on my balcony.
I'm a bit confused though - I would need a different transformer for this, right, rather than just adding a longer wire?
If so, do you have any company recommendations for EFHW transformers? The MyAntennas one looks good but is a bit expensive.
I suppose I could buy a toroid/core (looks like the FT82-61 core is a good choice) and make the transformer pretty easily also, but I'd like to see some that are known to be good so I can use them to base ideas and designs off if I were to build one anyway.
 

prcguy

Member
Joined
Jun 30, 2006
Messages
10,513
Location
So Cal - Richardson, TX - Tewksbury, MA
Don't use an FT82 core for an EFHW. For the 100 watt SSB and less range you can get by with a small FT-114A-43 core. For up to about 400 watts use a single FT-240-43 core, although an FT-240-61 should work. For higher power up to about 800 watts use two FT-240-61 cores and for full legal limit use three FT-240-52 cores. When you stack cores the inductance doubles and going to a lower permeability core is mo better.

Here is a video on how to wind the core and this guy does it right by pushing the middle of the wire through the core causing it to hug the core better vs pushing the end through which leaves you with lumpy windings.

For high power stuff this guy has done some research on the best cores and number of turns, although I don't like the way he winds them and its silly to use a huge doorknob cap at the feedpoint. The voltage there does not warrant that. On these big three core versions it looks like leaving a turn or two off is beneficial due to the added inductance of using multiple cores.



Cool, thanks. Hopefully, I am happy with these, but I would like to try an EFHW also. I may barely have enough room to drop 64ft if I mount it high on my balcony.
I'm a bit confused though - I would need a different transformer for this, right, rather than just adding a longer wire?
If so, do you have any company recommendations for EFHW transformers? The MyAntennas one looks good but is a bit expensive.
I suppose I could buy a toroid/core (looks like the FT82-61 core is a good choice) and make the transformer pretty easily also, but I'd like to see some that are known to be good so I can use them to base ideas and designs off if I were to build one anyway.
 

ScubaJungle

Active Member
Premium Subscriber
Joined
Mar 11, 2020
Messages
620
Location
West Central Florida
Don't use an FT82 core for an EFHW. For the 100 watt SSB and less range you can get by with a small FT-114A-43 core. For up to about 400 watts use a single FT-240-43 core, although an FT-240-61 should work. For higher power up to about 800 watts use two FT-240-61 cores and for full legal limit use three FT-240-52 cores. When you stack cores the inductance doubles and going to a lower permeability core is mo better.

Here is a video on how to wind the core and this guy does it right by pushing the middle of the wire through the core causing it to hug the core better vs pushing the end through which leaves you with lumpy windings.

For high power stuff this guy has done some research on the best cores and number of turns, although I don't like the way he winds them and its silly to use a huge doorknob cap at the feedpoint. The voltage there does not warrant that. On these big three core versions it looks like leaving a turn or two off is beneficial due to the added inductance of using multiple cores.
Awesome, Im going to see if I can pick those up, those videos are really helpful - thank you.
I was able to get the dipole spread enough to work. At first, I tried coiling it in a helical pattern up these panels I have, and it did okay. Then, I tried dropping one down towards the ground, about 50 feet, and the other I threw up onto the roof (taped a weight to one end and flung that thing!) and its working pretty well. I was able to pick up qsos from Bulgaria, Cuba, and a bunch of states. I was able to make contact with NC and GA via CW, but I think I need an amp as it was very spotty on them hearing my messages.
 

prcguy

Member
Joined
Jun 30, 2006
Messages
10,513
Location
So Cal - Richardson, TX - Tewksbury, MA
FT-240-43 and 61 cores are priced ok but the 52 mix is the most expensive at about $15 per core and when you use three it starts getting expensive. But you will have a transformer that costs a lot of $$ from a commercial vendor.

Awesome, Im going to see if I can pick those up, those videos are really helpful - thank you.
I was able to get the dipole spread enough to work. At first, I tried coiling it in a helical pattern up these panels I have, and it did okay. Then, I tried dropping one down towards the ground, about 50 feet, and the other I threw up onto the roof (taped a weight to one end and flung that thing!) and its working pretty well. I was able to pick up qsos from Bulgaria, Cuba, and a bunch of states. I was able to make contact with NC and GA via CW, but I think I need an amp as it was very spotty on them hearing my messages.
 
Status
Not open for further replies.
Top