Questions about wattage versus antenna in my situation

[WRWM519]

Please excuse my ignorance at this point, but I am requesting some clarification of several issues:

1.)  I have placed an N9TAX GMRS roll up slim jim in our upstairs attic at a window and have 28 feet of RG-8X out the window and down the side of an aluminum sided home to the basement, where at this time I am using a Baofeng UV-5G to primarily listen to a Ham repeater, and to key up two GMRS repeaters within 3-6 miles of me, where I can listen, but am told that I have weak reception of my signal. I am giving consideration to whether to buy a 25 watt mobile unit, Radioddity DB25-G, to use with the current antenna setup to boost power to the antenna, or go for a higher antenna on a mast, either the N9TAX or an alternative, which would require additional cable loss due to distance. I recognize I could use something like LMR-400, but would rather stick with RG-8X or equivalent if possible. Do you think that the additional wattage would get me the ability to be heard on the repeaters, with current setup, or should I look for a better antenna with mast, etc? I certainly agree that height = might in GMRS, but perhaps a higher gain antenna in my attic or more power at the transceiver might make the difference I am seeking.

2.) One reason I am considering a mobile unit is the ability to move it between vehicles as well as the basement... I do have the Nagoya 771g as well as a Nagoya UT-72G in one vehicle...and my second question has to do with whether the additional wattage compared to an HT receiver gets me more or more fars reception, as well as transmit fars, or do most mobiles fall back to the wattage of an HT in scanning or reception mode?

Much appreciate the support of the forum, and its various brains, in my quest. Thanks!

[dugcyn]

antenna is king if you have opportunity to put it high and proud (no neighbors complaint etc.) and if you want to be mobile i think your uv5g will hook to large antenna and dual as mobile in car. FYI IMHO more power is not a solution to your problem or needs. 3-6 miles to repeater leads me to believe you have something line of sight in the way, more power will just get junk signal working around this verses line of sight antenna pure signal. take this as advise from a newby but good signal less money wins. less you really want to get in the hobby? some small stuff just works.

[Lscott]

54 minutes ago, WRWM519 said:

but am told that I have weak reception of my signal.

The answer hinges on exactly what you mean by the above. It could be anything from low audio volume to a lot of white noise/static on your signal. The remedy depends on the symptom.

Since you are zeroing in on procuring a mobile radio to shuttle between the vehicle and house you can try that and see what improvement if any you get.

With 25 feet of RG-8X coax you're losing about 3.65 db, 57% of your transmitter power at 467MHz, based on a chart I have for coax cable types  in just the cable run. 

[Wannabe]

What is the antenna tuned for? 

[dugcyn]

good points above. loss in antenna wire could be issue. I am running real good wire, dont know what it is but 1/2 od stranded inside and out (in place when i bought the house). it is over 50 foot then another 50 up the mast. every situation is different. ran this setup with a uv5r and reached 40 miles from on top of a hill. your results will differ per terrain and mountains?

[WRQC527]

3 hours ago, WRWM519 said:

I have placed an N9TAX GMRS roll up slim jim in our upstairs attic at a window and have 28 feet of RG-8X out the window and down the side of an aluminum sided home

How close to the antenna is the nearest aluminum siding? Slim Jim antennas (and their J-pole cousins) do not like anything near them that can absorb or interfere with RF, especially metal. Not just the aluminum siding, either. If you have any insulation in the attic that has a metallic (foil-like) backing, it can cause problems too, as can metal window frames, etc. These antennas need to be completely in the clear to work best. Transmitting from inside a house with aluminum siding is no different than transmitting from inside a car.

[Sshannon]

11 hours ago, dugcyn said:

good points above. loss in antenna wire could be issue. I am running real good wire, dont know what it is but 1/2 od stranded inside and out (in place when i bought the house). it is over 50 foot then another 50 up the mast. every situation is different. ran this setup with a uv5r and reached 40 miles from on top of a hill. your results will differ per terrain and mountains?

That 100 feet of real good wire” that was in the house when you moved in could be the culprit as well.  Things can happen to coax that remain unseen but drag the performance way down.  A decent antenna analyzer could tell you whether that cable is actually good and what the losses are.  And it may be that most of the cable is excellent, but a little bit of the end at the connector has gotten moisture in it.  I would want to put an analyzer on your antennas anyway just to see what things look like.  I’d want to know cable losses, SWR, and coax length. At GMRS frequencies even 100 feet of LMR400 consumes half of the power before it reaches the antenna.

Check out this video by @marcspaz

 

[WRWM519]

Update, after reviewing the above, and taking your helpful suggestions:

Well, I have taken the GMRS dual band rated N9TAX slim jim out of the upstairs window (thanks for reminding me of the metal box of aluminum siding issue...I had had to wire an ethernet cable out to a Wifi repeater last year to get signal and photos back from outside battery operated wifi security cameras...same issue, DUH), and now it is strung up by zip ties on a long bamboo pole which is atop about 10 feet of 1/2" galvanized pipe stuck in the ground about 2 feet from the garage, and likely the top at about 16-18 feet estimated. The antenna only makes contact with the bamboo, and the galvanized starts about a foot or so below the bamboo. Using the same RG-8X cable and again my HT 5 watt, which altogether is measuring at 1.8 SWR. 

I am getting on one local repeater (Channel 30 at 462.725) about a 200 cycles per minute static, which I can squelch out, but is still there, and the repeater is in the direction of the garage shingled roof, which I am not yet above the peak of. In messing around and repositioning the antenna, I think I am getting clearer signal sometimes, but am wondering whether the zip ties I used to attach the slim jim twin lead could be the problem. To get it up more quickly for testing purposes, I zipped alternating sides of the wire leads to the bamboo at about 4 locations, whereas N9TAX seems to recommend punching holes in the plastic ladder rungs and zipping away from the wire leads and just on the rungs. Do you think that makes a difference?

I went ahead and ordered the 25 watt Radioddity DB25-G today, and considered ordering LMR or KMR 400 cable, but at this point, I will be repositioning antenna, adding the 25 watt as a base station, and seeing what happens. Will likely keep you posted, and thanks for the wonderful advice, and yes, the video, which I had seen before, was a great review and reminder, Thanks Steve!!

[Wannabe]

3 hours ago, WRWM519 said:

Update, after reviewing the above, and taking your helpful suggestions:

Well, I have taken the GMRS dual band rated N9TAX slim jim out of the upstairs window (thanks for reminding me of the metal box of aluminum siding issue...I had had to wire an ethernet cable out to a Wifi repeater last year to get signal and photos back from outside battery operated wifi security cameras...same issue, DUH), and now it is strung up by zip ties on a long bamboo pole which is atop about 10 feet of 1/2" galvanized pipe stuck in the ground about 2 feet from the garage, and likely the top at about 16-18 feet estimated. The antenna only makes contact with the bamboo, and the galvanized starts about a foot or so below the bamboo. Using the same RG-8X cable and again my HT 5 watt, which altogether is measuring at 1.8 SWR. 

I am getting on one local repeater (Channel 30 at 462.725) about a 200 cycles per minute static, which I can squelch out, but is still there, and the repeater is in the direction of the garage shingled roof, which I am not yet above the peak of. In messing around and repositioning the antenna, I think I am getting clearer signal sometimes, but am wondering whether the zip ties I used to attach the slim jim twin lead could be the problem. To get it up more quickly for testing purposes, I zipped alternating sides of the wire leads to the bamboo at about 4 locations, whereas N9TAX seems to recommend punching holes in the plastic ladder rungs and zipping away from the wire leads and just on the rungs. Do you think that makes a difference?

I went ahead and ordered the 25 watt Radioddity DB25-G today, and considered ordering LMR or KMR 400 cable, but at this point, I will be repositioning antenna, adding the 25 watt as a base station, and seeing what happens. Will likely keep you posted, and thanks for the wonderful advice, and yes, the video, which I had seen before, was a great review and reminder, Thanks Steve!!

Is it the dual band antenna or single band? What is it tuned for?

[WRWM519]

It is dual band, 2 meter and 70 cm, listed as:

Dual band MURS / GMRS Slim Jim Antenna with 10' or 16' Cable.

In the description:

Dual band versions Feature Trapped UHF section for proper band alignment.

I cannot say "what it is tuned for" aside from its being listed as GMRS and having the 2m/70cm tuning.

Thanks for the question.

[Lscott]

11 minutes ago, WRWM519 said:

It is dual band, 2 meter and 70 cm, listed as:

Dual band MURS / GMRS Slim Jim Antenna with 10' or 16' Cable.

In the description:

Dual band versions Feature Trapped UHF section for proper band alignment.

I cannot say "what it is tuned for" aside from its being listed as GMRS and having the 2m/70cm tuning.

Thanks for the question.

I've done an SWR scan of the dual band, MURS and GMRS, version I have. The testing was done with the antenna hanging by a non-conductive cord. These antennas are not that broad-banded.

https://forums.mygmrs.com/gallery/image/284-n9tax-murs-gmrs-scansjpg/

 

[MarkInTampa]

3 hours ago, Lscott said:

I've done an SWR scan of the dual band, MURS and GMRS, version I have. The testing was done with the antenna hanging by a non-conductive cord. These antennas are not that broad-banded.

https://forums.mygmrs.com/gallery/image/284-n9tax-murs-gmrs-scansjpg/

 

I did a SWR scan on my N9TAX GMRS Slim Jim as well, a bit different than yours. Overall I'd say it's a decent antenna for what it is and the price point. Much, much better than using a Nagoya 771G on a HT but sucks compared to my Comet GP-6 that cost 5x as much. After getting the Comet I relegated the Slim Jim as a scanner antenna for my SDR setup and it actually does a wonderful job for that. I bought a MFJ Discone antenna to replace it with but the Slim Jim actually performs better than the discone on receive, go figure...
 

[Lscott]

35 minutes ago, markskjerve said:

I did a SWR scan on my N9TAX GMRS Slim Jim as well, a bit different than yours. Overall I'd say it's a decent antenna for what it is and the price point. Much, much better than using a Nagoya 771G on a HT but sucks compared to my Comet GP-6 that cost 5x as much. After getting the Comet I relegated the Slim Jim as a scanner antenna for my SDR setup and it actually does a wonderful job for that. I bought a MFJ Discone antenna to replace it with but the Slim Jim actually performs better than the discone on receive, go figure...
 

The antennas are hand built. You might have got one that was better constructed. Also the connectors on the end can influence the results too. I have two of these antennas, both dual band. One is cut for MURS/GMRS and the other is for 2M/70cm. I forget which connector is on which antenna. One had a PL-259 plug while the other one had an "N" connector.

I might take some time to re-scan the MURS/GMRS version.

I've attached the scans I did for the 2M/70cm version.

I found some scans, the photos are poor quality, the builder posted on his web site. They are for the Ham bands. The best I can see it the UHF scan shows an SWR of 1.82(?) at 439MHz and 1.34(?) at 450MHz.

 

N9TAX-2M-70CM-VHF Scan.pdf N9TAX-2M-70CM-UHF Scan.pdf

[MarkInTampa]

2 hours ago, Lscott said:

The antennas are hand built. You might have got one that was better constructed. Also the connectors on the end can influence the results too. I have two of these antennas, both dual band. One is cut for MURS/GMRS and the other is for 2M/70cm. I forget which connector is on which antenna. One had a PL-259 plug while the other one had an "N" connector.

I might take some time to re-scan the MURS/GMRS version.

I've attached the scans I did for the 2M/70cm version.

I found some scans, the photos are poor quality, the builder posted on his web site. They are for the Ham bands. The best I can see it the UHF scan shows an SWR of 1.82(?) at 439MHz and 1.34(?) at 450MHz.

 

N9TAX-2M-70CM-VHF Scan.pdf 285.04 kB · 0 downloads N9TAX-2M-70CM-UHF Scan.pdf 285.33 kB · 0 downloads

Mine has a 16ft pigtail with a SMA connector on it. I never ran a SWR sweep on it for MURS until just now - it is actually quite good!

 

[Lscott]

16 minutes ago, markskjerve said:

Mine has a 16ft pigtail with a SMA connector on it. I never ran a SWR sweep on it for MURS until just now - it is actually quite good!

 

I wonder if anyone else has run any scans of the one they have.

 

[JoCoBrian]

On 4/2/2023 at 6:49 PM, dugcyn said:

good points above. loss in antenna wire could be issue. I am running real good wire, dont know what it is but 1/2 od stranded inside and out (in place when i bought the house). it is over 50 foot then another 50 up the mast. every situation is different. ran this setup with a uv5r and reached 40 miles from on top of a hill. your results will differ per terrain and mountains?

What was the coax used for before you bought the house?  It could be RG6 which will be even greater loss at UHF frequencies.  RG6 is 75 ohm coax and typically used for TV antenna or or cable TV feedline.  It's ok to use on HF. 

[Wannabe]

3 hours ago, markskjerve said:

Mine has a 16ft pigtail with a SMA connector on it. I never ran a SWR sweep on it for MURS until just now - it is actually quite good!

 

I just picked up a single band tuned to 465.000 and so far its performance has been good. I don’t have a SWR measuring device yet, but it outperforms my UT-72. 

[SpeedSpeak2Me]

On 4/4/2023 at 4:33 PM, Lscott said:

I wonder if anyone else has run any scans of the one they have.

 

 

N9TAX MURS/GMRS with 16' of RG-58A/U and PL-259 connector, that I purchased a month or two ago.  Antenna hanging from tree branch that is about 8' off of the ground.  Scanned with a RigExpert Stick Pro.

YMMV

 

148-156 MHz (covering MURS), 200 data points:

 

MURS Channels 1, 2, and 3:

 

MURS Channels 4 and 5 (Blue Dot, Green Dot):

 

440-480 MHz, 200 data points - this is a broad 40 MHz sweep, so accuracy suffers just a bit.  The following three screen captures provide better data for GMRS:

 

460-470 MHz, 400 data points showing minimum SWR:

 

Same as above, but showing rough center of GMRS repeater inputs:

 

And GMRS simplex:

 

[Bande1]

despite what everyone on the internet says the slim jim antenna is just a half wave ~3dbi antenna and isnt that good. Its really no different in performance than a $10 abbree 42". You already bought a radio but height means a lot more than power.

 

buy this antenna next and some KMR400 off amazon. If you have a tree hang the antenna in the tree 35-65ft up.

https://www2.randl.com/index.php?main_page=product_info&cPath=2_1500&products_id=69428

 

every 3dbi you add it effectively doubles your power. 6dbi quadruples power. This antenna will give you +8.5dbi in UHF over the N9TAX. Its big at 17.3ft in length but its economically priced and very good. Coax power loss goes up as you increase frequency. At GMRS freq with say RG-8X you're losing about 2% per foot of cable. 100ft of RG-8X will lose -8.5dbi. You should buy LMR400 or knockoff KMR400. Which will lose 2.7dbi per 100ft. This antenna and coax combo would make your HT the same radiated power as the DB-25G while having far more receive capability.

 

Get the antenna as high as you possibly can

[Lscott]

9 hours ago, SpeedSpeak2Me said:

 

N9TAX MURS/GMRS with 16' of RG-58A/U and PL-259 connector, that I purchased a month or two ago.  Antenna hanging from tree branch that is about 8' off of the ground.  Scanned with a RigExpert Stick Pro.

YMMV

 

148-156 MHz (covering MURS), 200 data points:

 

MURS Channels 1, 2, and 3:

 

MURS Channels 4 and 5 (Blue Dot, Green Dot):

 

440-480 MHz, 200 data points - this is a broad 40 MHz sweep, so accuracy suffers just a bit.  The following three screen captures provide better data for GMRS:

 

460-470 MHz, 400 data points showing minimum SWR:

 

Same as above, but showing rough center of GMRS repeater inputs:

 

And GMRS simplex:

 

Hummmm. I'll have to try it again. I used a RigExpert AA-1000, down loaded the data and read it into a MathCAD software for additional calculations. My results sort of match yours in some areas.

I did my testing indoors. Looks like I should try it again outside with the antenna higher up in the air and see if I can duplicate the results.

Too bad this site doesn't have a dedicated area to archive info like this. It would save a lot of repeated questions with people asking for this sort of data or trying to compare their results to see if they really do have a problem.

[SpeedSpeak2Me]

6 hours ago, Lscott said:

Hummmm. I'll have to try it again. I used a RigExpert AA-1000, down loaded the data and read it into a MathCAD software for additional calculations. My results sort of match yours in some areas.

I did my testing indoors. Looks like I should try it again outside with the antenna higher up in the air and see if I can duplicate the results.

Too bad this site doesn't have a dedicated area to archive info like this. It would save a lot of repeated questions with people asking for this sort of data or trying to compare their results to see if they really do have a problem.

I could probably improve on the numbers just a bit, as I just hung it from the closest branch I could reach.  I would expect it were up another 10' it would be improved.  The bottom of the antenna (balun) was only about 4' off the ground, but it served its purpose for the testing.  Since it only took a few minutes I'll eventually throw it further up in a tree and test again.

Also, I used the Bluetooth functionality and did the sweeps using the AntScope2 software on the phone, then saved off the .ASD files to be read later.  Not as good as direct USB-C to a laptop, but easier than trying to store the readings in a memory slot.

[dugcyn]

On 4/4/2023 at 3:25 PM, JoCoBrian said:

What was the coax used for before you bought the house?  It could be RG6 which will be even greater loss at UHF frequencies.  RG6 is 75 ohm coax and typically used for TV antenna or or cable TV feedline.  It's ok to use on HF. 

A very serious Ham setup, 50 foot tower with very nice 20' comet up top. think my post was misunderstood. reached 40 miles simplex 5 watts with this wire and antenna. my point was wattage is not king on fars.

 

[Luish19779]

The best GMRS Antenna I ever have is the Ed Fong GMRS jpole Antenna. I recommend and the prices is very cheap, compared with others GMRS Antenna in the market. Only need is a pvc psi 200 of 3 ft and good coax cable. I use LMR-400 with that antenna my SWR is 1.1. Get a Mobil radio(50w) with 20 amp power supply and you not need anything else. Good luck brother 

[Sshannon]

On 4/8/2023 at 7:46 PM, dugcyn said:

A very serious Ham setup, 50 foot tower with very nice 20' comet up top. think my post was misunderstood. reached 40 miles simplex 5 watts with this wire and antenna. my point was wattage is not king on fars.

 

Yes, I mistakenly conflated the information in your post with the situation of the OP. I’m sorry about that.

[OffRoaderX]

6 hours ago, Sshannon said:

I mistakenly conflated the information

The word is CONFUCKULATED ...