Base station radio

[GreggInFL]

I'm impressed with the mast.

[TDM827]

I know it's a boring solution.

But, I second the advice to have a roll up slim-jim for emergencies. In the event your base antenna gets trashed at least you have something, as long as you have something to string it to (tree limb, utility pole, antenna mast, gutter etc, chimney...). I believe they come in sizes up to about 20 feet.

[SteveShannon]

15 minutes ago, TDM827 said:

I know it's a boring solution.

But, I second the advice to have a roll up slim-jim for emergencies. In the event your base antenna gets trashed at least you have something, as long as you have something to string it to (tree limb, utility pole, antenna mast, gutter etc, chimney...). I believe they come in sizes up to about 20 feet.

They’re easy to build:

https://edsantennas.weebly.com/uploads/2/9/3/5/29358461/dbj-2_qst.pdf
 

[TDM827]

2 minutes ago, SteveShannon said:

They’re easy to build:

https://edsantennas.weebly.com/uploads/2/9/3/5/29358461/dbj-2_qst.pdf
 

Better Yet!

[WSGI548]

SoCal & Gortex,

If that was directed at me… Well I am hitting 3 repeaters, one 40 miles away, and the other two within 10-15 miles with my 5 watt HT, so… it works fine. The one that is 40 miles away people are constantly surprised I am able to hit as it is known for being hard to get into from where I live.

And yes, I did start with a cheap mag mount, because I wanted something I could use with my vehicle(Kia Soul) and at my house at first. The cheapy base antenna is actually not for me, eventually, I have a friend who is a little less fortunate who I am helping get a little set up, this will be given to him. But we only talk about 4 miles simplex, so it doesn’t need much. He lives in an HOA area, so has certain rules, hence the desire again for something he can setup and take down.

As for why I use the setup, I have overhead high voltage power lines for neighborhood power over my back fence, about 20 feet away from that antenna, and 30 feet in the air. Those power lines also attach to my house, as well as neighboring houses on either side, so there is no where in the the back half of my property or roof where I can put a mast that wouldn’t be within danger distance of those power lines if it went over, hence the reason I need something I can set up and take down.

Steve & WYRZ,

I am with you on the coax, I didn’t want to do the RG8X. I ordered 25ft of KMR400, but it is way to stiff to take up and down kind regularly. I did limit my run to 25ft, which if I was reading it right will be about 2-3 db loss, making that little antenna an 0 gain. That will be fine for my buddy, after I make sure it works around town. I was planning on going to a 5-6db gain antenna for myself, so that should make up some.

I can look at LMR240, but my understanding was it was solid core and again very stif, and not to be rolled rerolled to many times.

[WRYZ926]

Here are some links for you.

DX Engineering Max400 stranded core coax. $71 for PL259, $72 for N Type

JETSTREAM 400FLEX25A $40 at R&L Electronics

I have used both brands without any issues.. The R&L Jet brand uses Amphenol connectors which are top of the line if that matters to you.

I get trying to save money. But sometimes it is worth spending a little more for the proper coax. Standard RG-8 is better than RG-8X and LMR-240.

Per the coax loss calculator linked above. At 25 feet. you are getting 2.2 dB loss with RG-8X,  1.4 dB loss with LMR-240, 1.2 dB loss with RG-8, and 0.7 dB loss with LMR-400.

In reality, you won't notice much difference between LMR-400, LMR-240, or RG-8. But why limit yourself if you don't have to. Getting as much power to the antenna with the least amount of coax loss is more efficient. 

Plus the Jet brand is pretty cheap and still good coax cable.

[WSEZ864]

17 hours ago, WSGI548 said:

<snip>

Steve & WYRZ,

I am with you on the coax, I didn’t want to do the RG8X. I ordered 25ft of KMR400, but it is way to stiff to take up and down kind regularly. I did limit my run to 25ft, which if I was reading it right will be about 2-3 db loss, making that little antenna an 0 gain. That will be fine for my buddy, after I make sure it works around town. I was planning on going to a 5-6db gain antenna for myself, so that should make up some.

I can look at LMR240, but my understanding was it was solid core and again very stif, and not to be rolled rerolled to many times.

NOTE: edited loss figure error in bold below.

Not sure about the "KMR", but 25 feet of LMR400 would only have about 0.092 0.675 dB loss.

I use and suggest the 'flex' version of whatever coax brand you like. I use TM LMR400 UltraFlex for almost everything. I realize it's expensive, but compared to the rest of the radio/antenna investment, it's not a big portion.

We just talked about the difference between regular and flex type coax in another thread and the advantages of flex is that it is easier to work with (your advantage), can be bent into a tighter radius and can be more easily repurposed if you change setups.

The LMR240/240UF is decent coax, but at GMRS frequencies, I think it will have more loss than you want (@450mHz - 5.3dB/100 feet for LMR240 vs 2.7dB/100 for LMR400). It IS physically much easier to work with and much lighter than the 400 series, but you'd still probably want to used the 'flex' version in either case.

Specs:

https://timesmicrowave.com/cables/lmr-240-uf-coax-cables/

https://timesmicrowave.com/cables/lmr-400-uf-coax-cables/

Loss tables:

https://www.w4rp.com/ref/coax.html

 

 

[WSGI548]

WYRZ,

I will check those out at DX Engineering. That’s where I ordered the RG8X from, so I am sure I can send it back for a restock and exchange for something different.

Jay

[SteveShannon]

13 hours ago, WSEZ864 said:

Not sure about the "KMR", but 25 feet of LMR400 would only have about 0.092 dB loss.

 

You might want to check that number. Here’s a screenshot of the Times Microwave calculator page at 467 MHz frequencies for 25 feet.  It almost looks like their calculator doesn’t work correctly for LMR400 for short lengths:

[SteveShannon]

Thinking that perhaps the Times Microwave calculation page just didn’t work for short lengths of LMR 400 I increased the length to 250 feet, on the theory that I could then just divide the attenuation by 10 to get the attenuation for 25 feet.  Unfortunately, the calculator shows a number for 250 feet that’s just as obviously outside of commonly quoted loss values.  The calculator shows that at 467 MHz 250 feet of LMR400 will only have a loss of 3 db.  I also tried 1000 feet: 3.9 db.  I filled out their “Ask an Expert” form and told them their calculator appeared to be giving results that were outside of commonly quoted loss values.

[WSEZ864]

Thanks for checking that @SteveShannon. You're right, my number above is faulty - should be 0.675 dB (multiply the 2.7 dB per 100 feet from the specs by .25). Not sure what happened first time I calculated it, fat-fingered it I reckon.