SargeDiesel
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Posts posted by SargeDiesel
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I have my antenna and my whole set up run like you. I went to put the Comet mount on the hood like you have yours and I noticed a bead that goes all the way around the hood, it looked like where the hood seams are welded together.... I sanded it thinking it was an aluminum weld, but its a brown colored hard substance, either a polymer type glue or bondo type material used to secure the hood seams together where the hood top folds over the underside....
You had mentioned, you sanded to the aluminum to make contact with the mount, did you see what I am talking about and sand through it or is something different on yours , if possible a couple close shots of the underside of your hood and how you sanded to make a ground would be helpful.
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On 8/28/2022 at 8:57 AM, marcspaz said:
On some vehicles, I've even added secondary fuse boxes for my radios/amps/etc. that use bolt-down terminals
Thats about what I was considering doing, since the pre-assembled waterproof fuse holders are about that long anyway. A few connctions/splices seem unavoidable, so the real key will be getting good, tight crimp connections and clean soldiering. You definitely don't save any money making your own cable, but you most certainly will have one of superior quality. (Unless you buy in bulk and make several like you do). Ow that I am getting several accessories, I am most likely considering a 12v distribution box... like this (or making one myself):
https://badgeglow.com/product/simpleaux/?connection-type=Pre-wired Crimp Pigtails
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On 8/26/2022 at 3:08 PM, marcspaz said:
I always cut the T connector off and use power poles because that is my standardization. This allows me to move gear to any of my test benches or vehicles and have a standard connector, so it just plugs in.
How did you go about adding the inline fuses to the wires ? I've seen 10g fuse holders, but you would have to add them in.. which would mean two more additional connections on each line (or atleast one if you put the ring terminas on one end for the battery).. I am not sure how else to go about it.
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13 minutes ago, marcspaz said:
So... what is it on the battery side when transmitting, and then what is it at the radio when transmitting
I will test it this way.... and hopefully I won't see a greater drop than the stated .5v.... if so, I will be making my own cable.
You mentioned power pole connectors, is this for the radio lead to plug into the power cable.... seems this would require me to cut the harness/connectors coming out of the radio ?? Could you explain the purpose/benefit of the power poles ? Instead of just using the oem connection coming from the radio and at the end of the power cable in conjunction with inline fuses ?
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52 minutes ago, marcspaz said:
Where are you? Like, what state? I am in VA and have a ton of test equipment, if you're nearby.
Generous offer ! I'm in Alabama... but if/when I get your way, I will look you up !
I tested at the battery and the radio end and it was the same, I might need to move my meter over a click or two to see if there is a .5v loss.... I was thinking I needed to measure when keying the mic ? Other than using the needle point prongs and poking a hole in the wire, I wasn't sure how to do it.. or if I needed to.
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20 hours ago, marcspaz said:
Yeah, 14 is too small if you are going more than a few feet. When I had my MXT500, I cut the factory wires off and replaced them with 12, and 45 amp power pole connectors.
Ok, so I ordered the Comet RS-720NMO and my replacement MXTA26.
I checked my coax for any pinching, sharp bends or damage and it appears to be in good order.
After it being said that the 14g power cord is to small a gauge, in short of building my own, what would be a proper way to test it to see if it is up to task ? Also, even though I believe it to be good condition, same question for the coax.
Can any of the testing be done without buying expensive equipment that I will only use this once and most likely never use again ? I do have both analog/digital multimeters and the cheap SW-33+.
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1 hour ago, KAF6045 said:
Well... while it has "3 adjustment" points, it still doesn't allow rotating the NMO plate to the outside
Not sure I understand. It is the same mount that @marcspaz is using in the pic above except he has the RS-730 which is just a little bigger/heavy duty. I wanted the same mount but the NMO version only comes with the coax and I already have it. So I'm looking at the Comet RS-720NMO.
You are able to move the base (closest part to the lip) away from the hood and then adjust the plate(where the NMO attaches) back down to level it out. If this wont work, I think I'm missing something
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8 hours ago, KAF6045 said:
https://www.hamradio.com/detail.cfm?pid=H0-003079 (short coax, the longer coax model is out-of-stock at the moment)
Don't think I'd recommend https://www.hamradio.com/detail.cfm?pid=H0-006521 as it doesn't seem to allow rotating the lower hinge. Once you've mounted it and hinged the antenna to a vertical, the mount might be hitting the hood if the rise isn't sufficient to clear. Rotating the lower hinge would let you put the offset to the outside, away from the hood. The K400 allows rotating the lower hinge, and then pivoting up to vertical.
https://www.hamradio.com/detail.cfm?pid=H0-006551 (hah "does not damage expensive or leased vehicles", yet most of them want the under-lip set screws to make contact with bare metal so one has to scrape small dots of paint off from the underside
Has same problem as the previous.
This is the one I was lookind at since I already have the Midland low profile nmo mount/cable. Im just not sure about the fitment, But it looks like it will work. Look forward to your feedback.
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9 hours ago, marcspaz said:
TL;DR is internet slang for Too Long; Didn't Read. It's kinda funny.
Thank you I definitely read every word, and I appreciate others that are willing to share knowledge with those seeking it. I believe you have helped me out on the JT forum as well. I appreciate you.
9 hours ago, marcspaz said:Good luck! Looking forward to seeing what you get installed
I'm not drilling holes either.... I will reach out once I finally find what I am looking for and get it finished .
Thanks again.
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43 minutes ago, KAF6045 said:
I really should study my ARRL Antenna book again
Thanks for the great info and clarification.... I think I need to read it at least once... ha ha
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18 minutes ago, marcspaz said:
Most of the time, its 10 or 12
The MTX575 uses a 14g power cable with two 10a fuses. Maybe I just need to make my own out of 12g (50w radio). I did have to add about two feet to the OEM power cable... I crimped and shrink tubed, but did not soldier....
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29 minutes ago, marcspaz said:
I hope this doesn't turn into a TL;DR post. LOL
Not sure what this means... but thank you for the information. You put it in terms that I understand.
The current mount I am using is a side mount that uses the hood cowl bolt to ground to the vehicle. https://www.cooltechllc.com/2018-jeep-wrangler-jl/139-gladiatorwrangler-front-antenna-mount.html
The lip mount I have, that I mentioned is a Midland MTXA27, https://midlandusa.com/collections/micromobile-mounting-systems/products/micromobile-mxta27-universal-lip-mount .. you could put it on the side of the hood, but then your antenna would be a giant "curb feeler"... ha ha
So it seems I should search for a mount similar as yours ( side hood mount) and stick with the Midland MXTA26 Like I already had.
Thanks again.
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1 hour ago, OffRoaderX said:
I'm using the Midland MXTA26 on my JKU and a Tram UHF (dont remember the model) trimmed/tuned for GMRS on the wife's LJ... My 20+ and 98 miles is in good conditions with good/decent line-of-site, which we have in many areas in southern california.. Put a forest, hills, or houses full of fat-people between me and the other radio, and the fars will drop significantly.
Many/most radios are designed to operate at full power at 13.8V because thats what your car should be pumping out with the engine running - the MXT575 is one of those radios that craves 13.8V. Also bear in mind that some radios will just transmit on the low side (luck of the draw) and it is also possible that your (inexpensive?) meter is not 100% accurate.
Unfortunately, the Gladiator with its multi battery system has an on-demand alternator and does not automatically produce the 13.8v like most other/old school vehicles do. The whole electrical/battery system is a PITA... So as demand is needed the alternators current rises, or on full battery, its stays at 12.8v or so.... a lot of JT owners have commented on the JT forum thinking they have an issue.... I freaked out the first time I watched my gauge while driving... 12.8 at acceleration, and then 13-14.2 while de-accelerating or coasting.... so It looks like in the Gladiator, I will have to be happy with the 35-40 watts I was getting , unless there is some sort of amplifier that justifies the additional watts vs. cost.
ALSO
Would you mind giving me you input on the different wavelengths.... of course , if you are using the MXTA26 , I'm sure it is good enough for me, but I don't understand the 1/4, 1/2, 5/8 function ..pro/cons..
Thank you... your favorite viewer.
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@marcspaz I have my antenna cable ran the same as you, but I have my mount, mounted to the side hood cowl(plastic piece) it seems to be working well with the stainless steel mount and stainless mounting bolt. I am getting sub 1:5:1 SWR between the Midland ghost(MXTA35) and whip(MTXA26) antenna . I was curious about what antenna you and Randy @OffRoaderX have. I would like to know how he is getting the stated 20+ on simplex and almost 100 miles to a repeater ?? I recently broke my whip and I am looking to replace it. Someone mentioned the Larson NMO04450CHW , because of my mounting location and because it is a 1/2 wave and does not need a ground plane(GP). Some else mention my best performance would be from a 1/4 wave and even someone else said I should stick with the midland 5/8 wave... so I'm more than a little confused and I really do not understand the differences (pro/cons) of the different wavelengths. I have a lip mount, but it is a top hood style, so I would be willing to change mounts (to the side hood style) if it was absolutely necessary. I don't mind running the ghost for simple close trail situations, but I would really like to have a powerful whip for just in case. Lastly, Midland says my radio (MXT575) needs 13.8v to operate at peek wattage ( I watched Randy's youTube video testing it out, he was using a power source providing the 13.8v and he was getting 49+ volts into a dummy load. I noticed when testing mine in the Gladiator, while running , producing 12.8v (I still haven't figured out the IBS on our Gladiators and why at idle, I only was producing the 12.8v instead of 13.8v+) and the highest wattage I was able to obtain was around 38/39w using the whip and aout 35 using the ghost.... is this normal ? Thanks for any help !
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43 minutes ago, gortex2 said:
As I say over and over the ghost antenna is about as good as a dummy load. If your goal is to talk to a guy in front of you on simplex use it. If you need distance a 1/4 wave is a better choice. A quick search on this site will give you hundreds of posts with the differences between the ghost and the gain from Midland. There are also many posts on the JT/JL/JK/TJ antenna mounting solutions.
Thanks, new to the forum and radio in general, still a lot to figure out, thanks for the tip.
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2 minutes ago, axorlov said:
Marketers, who create such work for printed materials and web, often have no clue. It maybe a helical antenna (very like it is), it may have total length of the wire at around 5/8, but it is not 5/8 antenna.
Makes sense , in my situation do you think the 1/2 wave whip would work better ? (In easy newbie terms ... lol)
Thanks for all of your help... new to this, most is starting to sink in... but some Im still grasping at.... hopefully it will come together.
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34 minutes ago, axorlov said:
I just re-read the thread, it seems that your problem is low measured power. It could be that your power/SWR meter is to blame, or your antenna, or your cable
I did get a significant increase in wattage when I switched antennas from the whip to the ghost.. approximately 10 watts or so.
ButI also tried a completely different antenna ( the small 6 inch that came packaged with the MXT575) I placed it on a large pizza pan for the GP, if I remember correctly, it was in the 30 watt range, but nowhere near the advertised 50 watts. When I have seen theses tested on YouTube, they are constantly - 48/49 watts. I did test with the vehicle running.
The meter is cheap one, but I believe is fine for GMRS. it is a Surecom-SW33 plus. Here are the specs:
Max Power: 0.1 - 100W
V.S.W.R.: 1.00*19.9
SWR Detection Sensitivity: 3W min.
Frequency Range: 125MHz-525MHz
In/Out Impedance: 50Ω
Interface: SMA Female
Accuracy: mean +/- 5% -
25 minutes ago, axorlov said:
3.5" antenna can't be 5/8. 5/8 wavelength on GMRS frequency is around 16
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12 hours ago, axorlov said:
The usual NMO-mounted antenna is only a half of the antenna, the other half is a ground plane created by a conductive flat roof of the vehicle.
I understand about the ground plane(GP), I just misunderstood the function of the nylon/plastic spacer you see in the center hole of most mounts.
My issue is the design of the Jeep, the hood is Aluminum and non magnetic, no roof or trunk to speak of, so most owners use a lip mount or where I have placed it, on the side hood cowl... which doesn't provide an ideal GP.
Because of the lack of a good solid adequate GP surface, would the 1/2 wave antennas work better for me ? When I switched from the 5/8 wave whip to the 5/8 Ghost(3.5"), I got much better test results, but at a sacrifice of fars and half the dB. (From my understanding the ghost doesn't need as good of a GP as the whip, but both are 5/8 - so I really don't understand why)
I read the Larsen NMO0450CHW is a 1/2 wave and does not necessarily need a GP and I would get more fars over the 3.5" ghost and gain my dB back. Would this be a good choice for when I need more coverage over the shorter, less powerful ghost antenna ?
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1 hour ago, gortex2 said:
The ORing is to keep water out of the NMO. Nothing more.
If the o-ring is only for weather/water, why is the center post of the cable isolated from the mount with the nylon/plastic insert in the center hole of the mount ? Just for fitment ? I thought it was so the cable didn't touch/ground on the mount.... but that wouldn't make any sense if the top mount screws down onto and touches the mount anyway... ???
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22 hours ago, KAF6045 said:
For completeness -- ALL channels... INCLUDING the repeater inputs since they are 5MHz up from the simplex frequencies. However, you could probably skip the interstitials (in the current numbering scheme: 1-7, limit to 5W ERP) as they fall midway between the main channels. That leaves the main simplex channels (15-22) and the repeater channels (which may appear as 23-30, or as 15-22 with some indicator of repeater mode: rp15, 15R, etc.).
If your primary usage will be via repeaters, having a low SWR on the repeater channels will be more desirable. If you will be using simplex and repeaters, you'll have to compromise. Try to match simplex 22 and repeater 15 in SWR (simplex 15 and repeater 22 will be the worst SWRs, since you are tuning to put the minimum SWR around 464/465MHz, which is not a GMRS frequency band on its own, but midway between simplex and repeater frequencies.
This is where a standalone antenna analyzer (or a VNA -- though I don't have experience with those yet; mine arrived today, with the power switch in the ON position,
so the battery is extremely deadwith NO battery included [I've never seen a "standard flat-top 18650" locally -- button top and worse, protection circuit on some], and I hope it will charge). One: these devices don't spew high power RF, running in microWatt levels. Two: they let you sweep the frequency range while watching a needle and/or LCD display of SWR so you can rapidly get an idea of where the min-SWR is, and what the <2.0 bandwidth covers (Antenna analyzers tend to use of rotary dial to manually sweep, VNAs normally do the sweep via programmed parameters, and display graphically).You would 1: need a calibrated RF signal source to validate your power meter reading and 2: a reasonable dummy load for the power and frequency range (a 300W dummy load can only operate for half a minute at 300W before giving it a multiple minute cool-down; same unit is good for 3 minutes at 50W before cool-down. At less then 25W it can pretty much go on forever).
You probably won't see a full "advertised" power. Especially when that power level is also an FCC legal maximum output power (whereas the common 100W Amateur rig is not limited that way -- since 1500W is the legal max). Manufacturers may set the max to some level below the 50 (a few watts) just to ensure compliance with FCC regulations. There is also just unit to unit differences -- if the final check-out technician is having a bad day, they may not spend much time tweaking the final output levels and consider anything under 50W is good.
A few watts is insignificant. If I recall, to double the received signal strength (2 S-units on a meter?), one has to use something like 10X the power (I need to restudy my technical books. If a 5W signal brings up half the s-meter, going to 50W is likely to only tick one or two more dots on the uncalibrated LCD meters most units display.
I have a BTech GMRS-V2 -- advertised as 5W HT... My last test showed something between 2.5 and 3.5W. In contrast, my GMRS-V1 (a 2W design) showed around 2.5W.
The main feature of coax is that it is supposed to be shielded from outside electrical noise. The RF signal goes up the center conductor, and ideally tends to be balanced by the /inside/ of the braided shield (this is a much simplified description). Noise tends to be induced on the outside of the braided shield where is should be grounded out at the radio. Twin-lead has lower losses, but has to be kept a few inches away from any metal, much less something carrying electricity.
The zip-tie somewhat concerns me.. How TIGHT are they? You don't want to squeeze the coax and the inner insulator may deform, putting the shield closer to the center conductor... And that will become an impedance bump (SWR affect -- maybe small but...).
For my install, I bought some canisters (10ft lengths, at O'Reilly) of split-tubing plastic conduit. Press the cables in through the split, then use cable clamps or zip-ties to hold the conduit in place.
Icom ID-5100 transceiver installed in the under-bed well. The conduit has a few inches of antenna cable, power cables, external speaker cable, microphone cable, and control head cable.
The speaker, microphone, and control head cables split off at the driver's seat to go in to the central console (actually, I should double check. The speaker is mounted just behind console, but did I run control cables along central console, or with power cables and split off at the driver's kick panel?
Just to get more on topic -- those are the GMRS and CB (both mag-mount antennas) which run up the right side until passenger seat, then cross over to central console.
Thank you for your detailed, simplified response. Your build is really nice and well thought out...nicely done sir ! I made some changes.
I moved the antenna from the passenger side away from the am/fm antenna to the drivers side. I did mount it in the same location. I also I rerouted the antenna cable away from the power cable and wiring harness(I didnt have it zip-tied tight at all). The funny thing was , I got some increased wattage, but I also got a much higher SWR. Before the changes, my SWR was barely out of "safe" range @ 1:6:1 at high power. After the changes it varied between channels between 1:9:1 - 2:0:1. This initially led me to believe I needed to tune the "pre-tuned" antenna. I then switched out the whip antenna for a ghost antenna using the exact same setup, and achieved a large gain in wattage from the previous 25/27 to 35/37 watts and an almost perfect SWR reading throughout the channels. So I left it alone. So instead of tuning the Midland MXTA26, I am considering purchasing the Larsen NMO450CHW which is a " 1/2 wave collinear antenna, advertised not to need a ground plane. I think this might suit me better than the Midland since it is a 5/8 wave and the Jeep Gladiator is already antenna challenged in finding a good mounting location.
I do have a question I haven't asked yet...... concerning the design of the NMO mount, I see in every setup, there is a nylon or plastic insert in the center hole of the mount where the brass threaded piece comes up from underneath into the center of the mount for the top plate to screw on.... I was thinking this was to isolate it from coming into contact with the mount..... IF THIS IS THE CASE, when you screw the top brass mounting plate down onto the mount, it has an O-RING on the underneath side, my ?? is, is the O-ring there to protect from weather ? Or is it there to keep the plate from coming into contact with the top of the mount when screwed down tight. (functioning similar to the nylon/plastic insert) ? Because if it is the later, and it is the keep the brass plate from grounding on the mount, this may be some of my troubles... I tend to over tighten everything and upon changing locations of the mount, I realized I had tightened it down so tight, I collapsed the o-ring and the brass antenna adapter most likely was in contact with the mount.
I appreciate everyone's help !
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7 minutes ago, Sshannon said:
1. Make sure you’re using test equipment that’s high quality and accurately calibrated and appropriate for the frequency and power level you’re using. Make sure you’re testing at the specified voltage (13.8!) and using power cables that won’t cause voltage drop. It might help to visit a local radio shop.
2. That can depend on a lot of things. Is your power wiring noisy? How high quality is your coax? When it comes to antennas, everything affects everything and a noisy power cable parallel to the coax could cause problems.I when I tested my power cable, I had the same voltage reading at the battery and the end plug (if this is what you are referring to) but I haven't tested it while actually keying the handset.... I would have to figure how to do that.... lol
All of my hardware is from Midland ... maybe I have made a rookie mistake in assuming Midland products are high quality ???
Im really not sure how to go about testing "noisy cables"... so your advice to visit a local shop is probably a good idea.... the search is on.
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Maybe my question should be:
1. How do I properly test a newly installed GMRS radio for SWR ? What channel(s) should I use ?
2. How would I test to insure my radio is capable of outputting the advertised 50 watts of power ? (Hopefully using my current equipment)
3. Is running the antenna cable and power cable together ok ?
4. Is having both the antenna cable and power cable zip tied to the wiring harness ok ? Will it interfere with any of the other vehicle electronics ?
Thanks
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23 hours ago, Sshannon said:
1. For any given antenna, SWR changes with frequency. A graph of SWR vs. frequency often looks like there’s a sharp dip at the resonant frequency.
2. Where are you measuring the output power? A dummy load will appear to the transmitter like an antenna that has a very low SWR at every frequency. Also, was your Jeep running and putting out 13.8 volts or were you on battery at a voltage of 12+ volts? On battery power the output power will sag slightly. Or it might just have been the radio you received. Many things can affect output power: input power, antenna cable, antenna, ground plane, etc.
3. Pretuned to center channel probably means that it’s tuned to midway between the 462 (used for simplex communications) and 467 MHz (which you transmit to a repeater) frequencies of the band, or about 465 MHz.
4. Tuning the antenna to have a lower SWR might get you more transmitted watts, but honestly a few watts isn’t detectable in actual use. I recommend either leaving the antenna alone or tuning it to the frequency you transmit on most often. A higher frequency means a shorter antenna element, but if you shorten it too much it’s hard to undo.
Thank you for your response.
When I was measuring, I had the radio connected to the meter and the meter connected to the antenna.
The vehicle was turned off using only battery power.
My concern was the radio was only putting out half its power, I just want to make sure it is capable of putting out full power, like all the others of the same model I have seen tested.
Thanks again for your help.
Jeep antenna mount
in Technical Discussion
Posted
No apologies needed, you have been very helpful. It was my mistake, after I re-read ... I realized you mentioned that you "poked" through to the aluminum. I thought the bead was aluminum, so I was going to use the plates that came with the mount and have a great connection where I sanded, but I then realized that it wasn't aluminum. I have the 720 which is quite a bit smaller than yours, so to poke through the bead , I think I might need longer allen head screws.
So it looks like you were able to punture through the seam pretty well to the aluminum for a good ground.
I will give it another shot.