Homebase Setup

[WROA675]

On 10/16/2021 at 6:38 PM, Papatree said:

Gonna stop here for now (getting dark) until I get some more input on how to proceed

Monday improvements and update:

On 10/15/2021 at 8:20 AM, WRCQ487 said:

You should get a chart to see what the stinger needs to be cut down for gmrs

Rod cut to 8-7/16, on 462.650 (my nearest repeater)at 1.67 swr for high power, 1.22 for low power.

Manufacturers specs say 460 cut to 8-3/4 and 465 cut to 8-1/4, so I imagine that's about the best I can do.

Should I just leave it be or take it down a tiny bit more?

[BoxCar]

I would be very happy with those readings. Try different channels and get readings on those so you have an idea of the bandwidth of the antenna.

[WRCQ487]

2 hours ago, Papatree said:

Monday improvements and update:

Rod cut to 8-7/16, on 462.650 (my nearest repeater)at 1.67 swr for high power, 1.22 for low power.

Manufacturers specs say 460 cut to 8-3/4 and 465 cut to 8-1/4, so I imagine that's about the best I can do.

Should I just leave it be or take it down a tiny bit more?

I would say you are good to go. Now try it out and see what it can do. I run the same setup as you have but my antenna is in my attic. I get about 8 to 12 miles from base to mobile radio and I've reach repeater 30 to 50 miles away but those were big commercial repeater systems. 

[axorlov]

SWR 1.7 is ok. Nothing to write home about, but not terrible. The difference between low and high power measuring  usually (but not always) points to a crappy SWR meter. Surecom, right? I would not sweat over it too much.

 

 

[MichaelLAX]

Some quantitative data for the antenna mavens (of which I am not) to analyze from our contacts this morning:

According to Google Maps we are 22.9 miles away driving distance, which will be slightly less as the crow flies; due north/south from each other; with the western portion of the Angeles National Forest between us.

I am transmitting 18 watts with my Anytone AT-779UV (a/k/a Radioddity DB-20G) through my Comet CX-333 triband antenna on my 2nd story rooftop.

I hear you better simplex than I do through the 650 Contractor's Point repeater.

I hear you just as well, with 3 bars out of 10 on my meter, whether you are transmitting on 462.550, 462.625, 462.650 or even 467.650 (with me listening on the 650 repeater input).

So I would suggest unless anyone has something different to say, that you should not cut anymore off, as you will degrade your SWR on GMRS/FRS Channels 1-7 and 15-22.

The only caveat I have, is that if the other users of the 650 repeater object to the amount of noise you bring in with your audio, and since this seems to be the only repeater you can hit in the LA area, you might want to improve your SWR on 467.650 (or obtain a separate Yagi optimized for 467.650 and aimed at Contractors Point).

Strangely enough, I am unable to hear you with my Comet attached to my Icom IC-R7000, which has much better sensitivity than my Anytone.  I cannot explain this at this time, pending more experimentation.

[wayoverthere]

My need to experiment, I might test a little more before calling it done, though you're in pretty good stead where you are, and could just keep it as it is.

My thought process, but take it with not just a grain but a helping of salt...id test swr on simplex 15-21, and again on the repeater channels. If it's tending downward on as you go up in simplex, and rising as you go up the repeater Channels, you're likely pretty close, and your lowest swr is in the gap between simplex and repeater frequencies. If you're in that dip and the repeater channels (overall) are higher swr than the simplex, you could probably take a small amount more off to bias it a tiny bit more toward the repeater channels. If the repeater channels are already lower swr than the simplex, or the top of simplex (22) and the bottom of the repeaters (15) are about the same, I wouldn't take any more off.

And if I'm off base, by all means, let me know...I'm approaching from a logic/theory side of it, and know the real world doesn't always follow, and I'm always willing to learn. I know my 5/8 wave laird instructions said I should trim a good 3/4" to be centered where I want it, but nanovna and swr meter said it was almost spot on as is.

[WROA675]

3 hours ago, WRCQ487 said:

I would say you are good to go.

 

3 hours ago, axorlov said:

I would not sweat over it too much.

 

3 hours ago, MichaelLAX said:

So I would suggest unless anyone has something different to say, that you should not cut anymore off, as you will degrade your SWR on GMRS/FRS Channels 1-7 and 15-22.

 

1 hour ago, wayoverthere said:

My need to experiment, I might test a little more before calling it done, though you're in pretty good stead where you are, and could just keep it as it is.

Thanks everyone for the input and advice . In the days ahead I will put the swr meter back on and experiment some more with the different channels and range. I agree with the consensus, at this time it all seems adequate with the potential for some tiny adjustments.

Tomorrow I'm gonna go back into the rafters (oh joy) just to make sure the cable didn't get coiled, plus secure everything from point a to b.

One other piece of advice I picked up was the actual location of that bracket and how moving it to the peak of the roof which may give me another 8 feet, in height, clearing the roof for better quality tx/rx  (not sure that would affect my swr at all but it may cut down on the background noise).

Again, I appreciate all the assistance and thank you all for taking the time and making the effort in helping me get squared away.  

[wayoverthere]

1 hour ago, Papatree said:

 

 

 

Thanks everyone for the input and advice . In the days ahead I will put the swr meter back on and experiment some more with the different channels and range. I agree with the consensus, at this time it all seems adequate with the potential for some tiny adjustments.

Tomorrow I'm gonna go back into the rafters (oh joy) just to make sure the cable didn't get coiled, plus secure everything from point a to b.

One other piece of advice I picked up was the actual location of that bracket and how moving it to the peak of the roof which may give me another 8 feet, in height, clearing the roof for better quality tx/rx  (not sure that would affect my swr at all but it may cut down on the background noise).

Again, I appreciate all the assistance and thank you all for taking the time and making the effort in helping me get squared away.  

I forget if I posted it here or on one of the FB groups (I think here), but one test I did was coiling the cable vs just winding the extra around the room...though I atwont say that no effect is possible, least in my case (unmarked Midland mag mount cable), coiled together had a negligible effect on swr...I'll see if I can find the post. That said, since you'll be up there anyway, not a bad thing to do, especially as you secure it. Getting the extra height is a bonus too

Edit: went digging for the post and found it pretty quick in the swr meter thread. .09 change on one channel, .01 on the other, and no change in the middle.

https://forums.mygmrs.com/topic/2426-decent-cheap-swr-meter/?do=findComment&comment=27863&_rid=2738

Edited October 19, 2021 by wayoverthere
found post

[n4gix]

20 hours ago, axorlov said:

SWR 1.7 is ok. Nothing to write home about, but not terrible. The difference between low and high power measuring  usually (but not always) points to a crappy SWR meter. Surecom, right? I would not sweat over it too much.

Here is a handy colored chart listing VSWR ranging from 1:1 upwards. Note that 1.7 still allows just around 92% of the forward power being delivered to the antenna. In fact, anything lower that 2.2:1 is still considered "Good".