Ladder line underground

[VK4BLP]

I'm currently running rg213 to my tower some 40 metres away from my shack, and have finally woken up to the high losses from some 60 odd metres of rg213, and am seriously considering the idea of making up some ladder line to at the very least run from the shack to the tower.

The catch as I see it is that I currently run the rg213 underground via 90mm stormwater pipe along with rotator and remote antenna switch cabling. This along with pits at each end of this pipe occasionally partially filling with water.

Also I have a remote antenna switch on the tower which has so239 connectors on it, and I wasn't sure about baluns and how to go about it.

Was thinking of replacing the rg213 with lmr400, but that's still lossy, even though I'll be going up to 6m band on the tower, as the 2m/70cm antennas go up above the shack.

Why run it underground ? The idea was for visual aesthetics by hiding all the cables out of site, but that might have to change.

Appreciate your thoughts and suggestions.

[vk1da]

1 Ladder line is not lossless.

2. It needs to be kept spaced from any conducting or lossy material. The sides of a pvc pipe are ok but the dirt several mm away is lossy and possibly conductive. Keeping it spaced out from the other cables and even from the walls of the pipe would be a complex structural problem. All the cables would naturally tend to lie on the bottom of the pipe.

I can imagine a lattice like structure of spacers that may make this feasible but it would be quite a delicate assembly effort. Compared with this, pulling a few coax and control cables through the conduit would be a lot simpler.

No chance of building a shack next to the tower?

73
Andrew


Andrew Davis VK1DA & VK2UH
Sent from my iPhone using Tapatalk
Vk1da.info vkfaq.ampr.org vk9na.com

[VK4BLP]

1 Ladder line is not lossless.

There's always losses somewhere, but ladder line isn't anywhere near as lossy as rg213 over the distance I am running, and I only mentioned it in a comparative fashion.

2. It needs to be kept spaced from any conducting or lossy material. The sides of a pvc pipe are ok but the dirt several mm away is lossy and possibly conductive. Keeping it spaced out from the other cables and even from the walls of the pipe would be a complex structural problem. All the cables would naturally tend to lie on the bottom of the pipe.

I can imagine a lattice like structure of spacers that may make this feasible but it would be quite a delicate assembly effort. Compared with this, pulling a few coax and control cables through the conduit would be a lot simpler.

Two words "complex structural" says it all, doesn't it ?

Looks like if I'm serious about things between the shack and the tower, I'm going to have to put some poles in and run it overhead.

No chance of building a shack next to the tower?

Not a chance at this point of time. I'm more likely to relocate the tower than I am to build a shack next to the tower.

Thanks for your reply.

[VK3DXE]

Keep your eyes open for some LDF5-50. I've seen good lengths come up at decent prices at hamfests occasionally. The total cost may well end up less when you factor in the added costs of the extra hardware needed to run open line.

[ZL4DK]

If you do get some ldf4-50 (or even some thicker cable) but can't find connectors for it at reasonable prices then just solder some short lengths of rg213 to the ends. If you do a good job of keeping the ratio of inner to outer diametres correct across the joint you could run this arrangement up to 2metres and struggle to notice any mismatch. At 6 metres or lower you won't notice the difference. The hard part is waterproofing the arrangment.

Regards
David

[VK4ADC]

Re David ZL4DK's suggestion

The RF Shop in Brisbane has N male connectors for LDF4-50 starting at about $14.50 & females from just under $17, both prices inc GST
http://rfshop.com.au/Store/tabid/63/Lis ... rew+Heliax

They are easy to use so no need to make the 213-addon and insulate/waterproof it - and solves the possible issue of overheating the heliax dielectric while trying to establish the outer connections while soldering.

Heliax is a lot easier to work with than trying to fabricate/use balanced line, particularly if you are contemplating putting it underground.

You will often find used heliax connectors (LDF4-50, 5-50 and others too) at Hamfests if you arrive early and do a quick squiz around the tables, grabbing what you can while you can.

[VK4BLP]

Thanks for the suggestions guys, I'm starting to go right away from ladder line now, due to the difficulties of hooking up my remote antenna switch, as well as needing to run it aerial.

[VK2TDN]

LMR400 (CFD400) has only 1.74 dB loss over 60m @ 50MHz. Hardly worth worrying about and much less the lower in freq you drop.

Dave

[VK6DZ]

These connectors fit LDF4-50 http://www.ebay.com.au/itm/380327877466, very easy to fit as there is no soldering.

[VK2GOM]

...and if you buy directly off them rather than via eBay they are even cheaper; $2.80 each, free post. You just have to pay $3 for an EMS tracking number for orders under $200.

They certainly sell a wide range of connectors, and their cable assembly wizard looks great for custom made patch cables of exact lengths.

http://www.rfsupplier.com

73 - Rob VK2GOM / G0MOH

[VK4BLP]

Thanks for all the responses guys, I've made the decision and have ordered lmr400 (Times) from the USA for the run.

This way I can keep it all underground to the tower, and have less loss than rg213.

[VK3ZPF]

Thanks for all the responses guys, I've made the decision and have ordered lmr400 (Times) from the USA for the run.

This way I can keep it all underground to the tower, and have less loss than rg213.

Did you order LMR400 or LMR400DB? The DB has a gel impregnated braid to prevent water 'wicking' along. LMR400 soaks up water like a sponge if the jacket is broken.

Did you also order some connectors as the size of the cable is different to RG8 and RG213 and connectors for these cables don't really fit LMR400 all that well.

[VK4BLP]

Thanks for all the responses guys, I've made the decision and have ordered lmr400 (Times) from the USA for the run.

This way I can keep it all underground to the tower, and have less loss than rg213.

Did you order LMR400 or LMR400DB? The DB has a gel impregnated braid to prevent water 'wicking' along. LMR400 soaks up water like a sponge if the jacket is broken.

Did you also order some connectors as the size of the cable is different to RG8 and RG213 and connectors for these cables don't really fit LMR400 all that well.

Connectors are coming with it, but only LMR400, not the DB version of it.

I'll just have to make sure I don't split the outer jacket then.

I might have to track down some extra connectors for spares though, and I guess I should have order the extras at the same time.... nothing quite like 20/20 hindsight !