3 element beam install on my tower.

[SMILEX2692002]

I have a Imax 2000 on my tower with Lmr 400 coax.
Can I still use this coax with a Maco M103C mounted horizontal?
The coax is stiff and I think LMR 240 might work better.
I don't run more than 100 watts PEP on SSB and no more than 25 watts PEP on AM.

I was planning on using my Sirio D27 dipole mounted vertical off the tower as high as I can put it without it interfering with the M103C for my local talking antenna. I don't do much local talking.
I know I could use the LMR 400 with this antenna since it will be in a fixed location but was thinking it would be overkill since I run lower power anyway.


Some might ask why not mount the Imax 2000 above the M103C?
I have thought about doing that also but my Ham 3 rotor says its only able to accept up to 7.5 sq. ft. wind surface area load.
My rotor will not be mounted inside my tower. I have the lower mast bracket and will be mounting it to a short mast comming out of the tower.
I don't want to stress the rotor with the Imax 2000 above the beam.

My goal is to use the M103C for skip and long distance contacts.
The Sirio D27 for local talking.

 

[Beetle]

I have a Imax 2000 on my tower with Lmr 400 coax.
Can I still use this coax with a Maco M103C mounted horizontal?
The coax is stiff and I think LMR 240 might work better.
I don't run more than 100 watts PEP on SSB and no more than 25 watts PEP on AM.

I was planning on using my Sirio D27 dipole mounted vertical off the tower as high as I can put it without it interfering with the M103C for my local talking antenna. I don't do much local talking.
I know I could use the LMR 400 with this antenna since it will be in a fixed location but was thinking it would be overkill since I run lower power anyway.


Some might ask why not mount the Imax 2000 above the M103C?
I have thought about doing that also but my Ham 3 rotor says its only able to accept up to 7.5 sq. ft. wind surface area load.
My rotor will not be mounted inside my tower. I have the lower mast bracket and will be mounting it to a short mast comming out of the tower.
I don't want to stress the rotor with the Imax 2000 above the beam.

My goal is to use the M103C for skip and long distance contacts.
The Sirio D27 for local talking.[/QUOTE
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If the 400 is already there and in verifiably good condition, the best thing would be to get a length of something like RG-213. Connect it to the 400 and to the feedpoint. You might want to lower the 400 a bit so the connector sits a foot or so below the beam. That way the 400 won't have to flex as you turn the beam. The LMR-400 has a solid center conductor and won't last very long turning. There is LMR-400XF (Xtra Flexible) which has a stranded center conductor and would be fine by itself. RG-213 (the REAL stuff; Mil-Spec and all) will be fine. Put up the beam and lose the vertical.

 

[Mudfoot]

But keep the Sirio dipole.

 

[Staybolt]

It always gets me how CBers think they need to use this ultra low loss and very expensive LMR 400 coax. I get by with RG 8U and mini 8u and call it a day. The LMR 400 is great for UHF and VHF operations but way overkill for HF use...

 

[Mudfoot]

In many ways, your correct. If'n your gonna run some big power or a pretty long run, then the low loss stuff is good.

I use mini 8 on most of my wires that I can easily service. On more permanent antennas that are difficult to reach/maintain, I use 9913F7. I use it because of it's durability and life expectancy in the elements compared to even the best rated 8x.

The Belden is going to outlive me, the mini 8 might not.

 

[SMILEX2692002]

It always gets me how CBers think they need to use this ultra low loss and very expensive LMR 400 coax. I get by with RG 8U and mini 8u and call it a day. The LMR 400 is great for UHF and VHF operations but way overkill for HF use...

I used the Lmr 400 on my Imax 2000 due to having extra footage left over from my VHF/UHF antennas. It has worked perfectly on my CB antenna and my 2 meter/70cm antennas.

I have some Lmr 240 coax that I use on my Sirio D27 dipole and it also works great.

I like the Lmr 240 coax due to its thin size and its easy to run around my radio room.
Not to mention the price is much lower than the Lmr 400.

My coaxial runs are 50 to 60ft.
40ft up the tower, the remaining into my radio room.

Based on Times Microwaves calculations.
Attenuation (dB per 100 feet)
LMR-240® 1.3 @ 30 MHZ
LMR-400® 0.7 @ 30 MHZ

 

[Captain Kilowatt]

It always gets me how CBers think they need to use this ultra low loss and very expensive LMR 400 coax. I get by with RG 8U and mini 8u and call it a day. The LMR 400 is great for UHF and VHF operations but way overkill for HF use...

Uh-oh. I don't even want to hear what you think of me using Andrew LDF-4 heliax for all my HF antenna right down to 160m.

 

[wavrider]

Uh-oh. I don't even want to hear what you think of me using Andrew LDF-4 heliax for all my HF antenna right down to 160m.

Price was right:laugh: If I could get a hold of the heliax for cheap enough I would use it too.

 

[Captain Kilowatt]

Price was right:laugh: If I could get a hold of the heliax for cheap enough I would use it too.

Yeah I managed to acquire several hundred feet of used and about 135 feet of brand new still on the reel for nothing when we decommissioned a broadcast site and reinstalled everything new. Sometimes ya just get lucky. It would actually cost me more if I went with RG-213 or something equal as I would have had to actually buy it.:laugh:

 

[SMILEX2692002]

If the 400 is already there and in verifiably good condition, the best thing would be to get a length of something like RG-213. Connect it to the 400 and to the feedpoint. You might want to lower the 400 a bit so the connector sits a foot or so below the beam. That way the 400 won't have to flex as you turn the beam. The LMR-400 has a solid center conductor and won't last very long turning. There is LMR-400XF (Xtra Flexible) which has a stranded center conductor and would be fine by itself. RG-213 (the REAL stuff; Mil-Spec and all) will be fine. Put up the beam and lose the vertical.[/QUOTE]

So I made a 6ft jumper from Lmr 240. I will connect it to the beam and then to a SO-239 barrel connector. The Lmr 400 will run back to the radio room from the other end of the SO-239 barrel connector.
I have never used a SO-239 barrel connector before so I figure I should try and seal it so moisture stays out.

 

[wavrider]

coax seal or good old black tape

 

[loosecannon]

It always gets me how CBers think they need to use this ultra low loss and very expensive LMR 400 coax. I get by with RG 8U and mini 8u and call it a day. The LMR 400 is great for UHF and VHF operations but way overkill for HF use...

yes, it is overkill if your only consideration is the loss factor.

i do not believe this is why LMR400 has become so popular over the last few years in the CB circles.

i believe it is because of the superior shielding LMR400 offers over standard RG8u coax.

the LMR coax has a bonded foil shield in addition to the 95% braid, and when trying to peacefully co-exist with your neighbors while running a modded CB and amp, you need all the help you can get.

not to mention the fact that RG8u is now manufactured by so many different companies that its harder to determine how well made a particular brand is.

buying LMR400 is an investment in itself but i for one am glad that good coax is being sought after these days.

anyone remember the days when every new CBer just went to radio shack and bought 50ft of their RG58u?
you could poke pins in between the braids in that coax. LOL
LC