[NLRS] Tower coax switch vs. separate runs

[Larry Peterson]

I have been through many iterations of research and application, Paul.  You are not at very high frequencies so separate coax lines aren’t very expensive.  I presume you might be using something like LMR400-type coax.

So there is great simplicity in just running four separate coax lines.

For me, I go up to 1296 MHz and also high power amplifiers.  I decided to use a version of LMR600 out of Italy.  Now that gets very expensive.  Plus, there is significant attenuation, so I place my transverters in the garage...and run just a single LMR600 feed line about 110’ from the ham shack.  That saves me over $1,000 in feed line costs.  

Now if you are getting switches, I’ve found at high power that they fail at high frequencies.  Again, you are at low frequencies, so you can probably use the more common switches, say from Alpha Delta. 

If you ever go to 70cm, then many switches are poor.  And I burnt out my high-quality MFJ switch at high power.  I have since gone to coax relays which I obtained from Roger at the DX Shop in England.  This has been working well.  I remote switch via 12 and 24 VDC lines from within the ham shack to four different coax lines going to the tower for my VHF+ operations.  None of this is necessary for my HF, eg, I have a Force 12 C-3 Yagi.

Another thing to consider is using a duplexer.  I am using a Comet triplexer so I can use one expensive LMR600 feed line up the tower and then use jumpers from the mast-mounted triplexer to 2m, 125cm and 70cm antennas.  I just have to be careful not to over-power when operating digital.  

As for grounding of the coax and rotor, I go to DX Engineering.  I have used Alpha Delta for lower frequencies and Diamond lightning surge suppressors for higher frequencies.  It is helpful to conduct attenuation tests to be sure that those surge suppressors work well.  They can be touchy at high frequencies.

Finally, as you go to higher frequencies, be sure to use N connectors.  PL-259 connectors are very poor, whereas N connectors do not give you impedance problems.   With you being only at 2m, you can get by with PL-259s yet.

Good luck.

Larry WA9TT

> On Jun 7, 2020, at 10:30 AM, Paul Beckmann <wa0rse at gmail.com> wrote:
> 
> Hello, everyone!
> 
> I've been tackling the many challenges/decisions of installing a
> tower-based antenna system over the last number of months. One that has now
> come into view is the connection between the antennas and the ground.
> (Ground*ing* is another topic.) Here are relevant parameters:
> 
> Tower: 72' UST crank up
> Distance from tower to shack: < 30'
> Antennas:
> 
> TH5Mk2 tribander
> Cushcraft WARC Yagi
> 6m Force12 LFA
> 2m Force12 LFA
> 
> 
> So, do I run 4 pieces of coax up the tower or one with a tower switch? I'll
> be running a KW on HF. I don't (yet) have mast-mounted preamps for 6 and 2.
> I'm thinking of mast mounting my SSB transverters on the tower. Thoughts on
> that?
> 
> As some of you know I've spent a ton of time over my ham radio days to
> actually getting permission to put up a tower. Now that I have permission,
> all of the dimensions of a high-quality installation have presented
> themselves. Not a simple thing to do correctly...
> 
> 73
> --Paul, wa0rse
> * Paul Beckmann*
> *Vista Meadows Homestead*
> *30125 719th Street*
> *Lake Township, MN 55041*
> *wa0rse at gmail.com <wa0rse at gmail.com>*
> *612-414-0302 (cell, leave msg)*
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