Topics

Antenna time... help appreciated

Ryan - KJ7GIE
 

Jim, Because of the short lengths I'm running I thought I could get away with something less than LMR400 but... being as I'm running short lengths the cost difference between LMR400 and RG8X is negligible so I went with LMR400 ultra flex anyway. Thanks for the link.

Paul, I had not heard of the GP1. Looks excellent for my use and, yes, I'd like to play antenna at some point and borrow it. Also the Ed Fong stuff looks great as well. I'll let you know when I have time and I'll put an extra run of coax in the attic in preparation for trying out new things. Your DTV dish idea sounds intriguing. I have a DTV antenna on my roof I am not using but it's on the wrong side of the house. It's in an area that faces south but facing west it would cross the top of my house as it sits pretty low on the roof. Not sure that would be any better or worse than using the attic. Intriguing though.

Lou, much appreciate the tip on the Jet-Lube will certainly get some.


Placed an order with HRO for the GP-146/440 and the OSJ-220. Price was right on these to get me started. Also have on the way the panel, coax, and a short patch of RG-188 for my HT. Seems like a good start. Thanks again for all the help.

Lou Giliberto (KD7HCW)
 

There's a lot of good advice already, so I'll just add a few thoughts.

As everyone said, you want to use LMR-400.  However, depending on how you route the cable, you may want to consider LMR-400 UltraFlex.  It uses a stranded center that makes it more flexible with similar operating characteristics to LMR-400.


You'll also want conductive anti-seize on the connections especially if you are going to be connecting / disconnecting them often.  I like Jet-Lube SS-30; I use it on all my connectors.  A little goes a long way.

 

 

 

Paul Butzi (W7PFB)
 

There are a lot of very good 2m/70cm antennas out there that fit into a 5’ space.

I’m fond on the Comet GP1, which will fit crossways in most car trunks/waybacks, and I use a GP-1 for my standard portable 2m/70cm go box along with a speaker stand and short extension mast.  The win of the GP-1 is that it’s about 3db more gain than a j-pole on 70cm.  If anyone would like to try my GP-1 just let me know, I’ll swing by and we can plan antennas.

If gain isn’t an issue but you want 2m, 1.25m, and 70cm, Ed Fong sells a tri-band base antenna (https://edsantennas.weebly.com/about.html).  Same gain as a j-pole (indeed, on 2m and 70cm it’s a jpole) and no radials.  I’ve ordered stuff from Ed and found him pleasant to do business with.

I would run LMR-400 or something similar between the patch panel and the attic.  If the run between the patch panel is short, I’d suggest just using RG-8X for that.  If the run between the patch panel and the radio is long, then I’d probably go with LMR-400 most of the distance and a short 5ft section of RG-8x for the rest.  Connecting LMR-400 to the back of the radio can be a bit of a hassle as it’s fairly stiff.

Somewhere I have plans for a j-pole equivalent antenna made by cutting a slot into a DirectTV dish - the slot is actually the radiator.  I have a couple of disused dishes laying about if someone wants one to give this a whirl.  The resulting antenna is not directional but as homeowner’s assocations often have exemptions for TV dishes, this would be a sly way to sneak a 2m/70cm antenna past.

If you have a metal roof then an antenna in the attic won’t work well.

-p W7PFB
73, Don’t forget to smile and have fun!

On May 25, 2019, at 2:00 PM, Ryan - KJ7GIE <rsm@...> wrote:

I'm starting to work through my first antenna purchase and set-up. A big thanks to Benjamin (KG7BTU) for coming over and letting me borrow a J-Pole as I at least know what will work now. Primary goal is to hit the club repeater on Cougar and I can do that with the borrowed antenna. Other goals, over time, include:
137 Mhz (NOAA weather sat)
144.39 Mhz (APRS)
2m
1.25m
70cm

I have a requirement to put the ant in my attic for now. Various reasons for this but that limits me in height but not necessarily going wide. I only have about 5, maybe 6, feet of height in my attic. I've decided not to look at high element directionals at this time because of cost. But, at some point, this may be the way to go if I keep things in the attic.

So, I may need more than one ant and certainly something specific for satellite. But.. I want to focus on 2m/70cm right now. Here's my shopping list what do you think?

- Arrow GP146/440, this is the same 70cm element as the borrowed j-pole but uses a ground plane design for the 2m element
- MFJ-4706, Coax Patch Panel *more on this later
- Coax? This is where I can use some help as I'm not sure for a set-up like this what type of coax I should be buying. I assume it is preferable to run the same kind of coax from the back of the patch panel (ant side) and out the front (radio side).

Arrow would go up in the attic and I'd run coax from the attic, through the ceiling, and into a closet in a bedroom. That coax would terminate on the back of the 4706. This run is ~15 feet so relatively short (even shorter if I mount the ant above the bedroom). I then need to a run of coax from the front of the 4706 to a desk in the bedroom for when I'm in front of the radio. This run would be another ~15 feet. If both of these patches need to be the same coax I'd like to be able to re-use my radio coax for multiple antennas so I'd like to make all coax runs the same. Trying to do a little planning ahead. I realize not every bit of coax is perfect for all bands but hoping if I do a little planning now I won't need multiple different patches to my radio later.

If / when I put additional ants up I will run them to the same panel in the closet and just move my "radio coax" at the panel. When I'm not using the radio I can tidy up everything and put it away. That's the main reason for using something like the MFJ-4706.

So, thoughts? Other ants I should look at? Anything blatantly wrong with my shopping list?

As always your help is much appreciated. I'd like to get some things on order this week so I can get Ben his ant back.




W7ABD
 

Hi Ryan,

As you learned (hopefully <grin>) in class, the higher the frequency - the higher the loss in coax.  So you will want to run LMR-400 for the dual band 2m/70cm antenna.  For very short lengths (like patch panels), RG8X is fine.

Check out: http://www.w4rp.com/ref/coax.html 

A good reference for different types of coax and their associated loss by frequency.

Jim
W7ABD


On 05/25/19 14:00, Ryan - KJ7GIE wrote:
I'm starting to work through my first antenna purchase and set-up. A big thanks to Benjamin (KG7BTU) for coming over and letting me borrow a J-Pole as I at least know what will work now. Primary goal is to hit the club repeater on Cougar and I can do that with the borrowed antenna. Other goals, over time, include:
137 Mhz (NOAA weather sat)
144.39 Mhz (APRS)
2m
1.25m
70cm 

I have a requirement to put the ant in my attic for now. Various reasons for this but that limits me in height but not necessarily going wide. I only have about 5, maybe 6, feet of height in my attic. I've decided not to look at high element directionals at this time because of cost. But, at some point, this may be the way to go if I keep things in the attic.

So, I may need more than one ant and certainly something specific for satellite. But.. I want to focus on 2m/70cm right now. Here's my shopping list what do you think? 

- Arrow GP146/440, this is the same 70cm element as the borrowed j-pole but uses a ground plane design for the 2m element 
- MFJ-4706, Coax Patch Panel *more on this later 
- Coax? This is where I can use some help as I'm not sure for a set-up like this what type of coax I should be buying. I assume it is preferable to run the same kind of coax from the back of the patch panel (ant side) and out the front (radio side).

Arrow would go up in the attic and I'd run coax from the attic, through the ceiling, and into a closet in a bedroom. That coax would terminate on the back of the 4706. This run is ~15 feet so relatively short (even shorter if I mount the ant above the bedroom). I then need to a run of coax from the front of the 4706 to a desk in the bedroom for when I'm in front of the radio. This run would be another ~15 feet. If both of these patches need to be the same coax I'd like to be able to re-use my radio coax for multiple antennas so I'd like to make all coax runs the same. Trying to do a little planning ahead. I realize not every bit of coax is perfect for all bands but hoping if I do a little planning now I won't need multiple different patches to my radio later. 

If / when I put additional ants up I will run them to the same panel in the closet and just move my "radio coax" at the panel. When I'm not using the radio I can tidy up everything and put it away. That's the main reason for using something like the MFJ-4706. 

So, thoughts? Other ants I should look at? Anything blatantly wrong with my shopping list? 

As always your help is much appreciated. I'd like to get some things on order this week so I can get Ben his ant back.




Ryan - KJ7GIE
 

I'm starting to work through my first antenna purchase and set-up. A big thanks to Benjamin (KG7BTU) for coming over and letting me borrow a J-Pole as I at least know what will work now. Primary goal is to hit the club repeater on Cougar and I can do that with the borrowed antenna. Other goals, over time, include:
137 Mhz (NOAA weather sat)
144.39 Mhz (APRS)
2m
1.25m
70cm

I have a requirement to put the ant in my attic for now. Various reasons for this but that limits me in height but not necessarily going wide. I only have about 5, maybe 6, feet of height in my attic. I've decided not to look at high element directionals at this time because of cost. But, at some point, this may be the way to go if I keep things in the attic.

So, I may need more than one ant and certainly something specific for satellite. But.. I want to focus on 2m/70cm right now. Here's my shopping list what do you think?

- Arrow GP146/440, this is the same 70cm element as the borrowed j-pole but uses a ground plane design for the 2m element
- MFJ-4706, Coax Patch Panel *more on this later
- Coax? This is where I can use some help as I'm not sure for a set-up like this what type of coax I should be buying. I assume it is preferable to run the same kind of coax from the back of the patch panel (ant side) and out the front (radio side).

Arrow would go up in the attic and I'd run coax from the attic, through the ceiling, and into a closet in a bedroom. That coax would terminate on the back of the 4706. This run is ~15 feet so relatively short (even shorter if I mount the ant above the bedroom). I then need to a run of coax from the front of the 4706 to a desk in the bedroom for when I'm in front of the radio. This run would be another ~15 feet. If both of these patches need to be the same coax I'd like to be able to re-use my radio coax for multiple antennas so I'd like to make all coax runs the same. Trying to do a little planning ahead. I realize not every bit of coax is perfect for all bands but hoping if I do a little planning now I won't need multiple different patches to my radio later.

If / when I put additional ants up I will run them to the same panel in the closet and just move my "radio coax" at the panel. When I'm not using the radio I can tidy up everything and put it away. That's the main reason for using something like the MFJ-4706.

So, thoughts? Other ants I should look at? Anything blatantly wrong with my shopping list?

As always your help is much appreciated. I'd like to get some things on order this week so I can get Ben his ant back.