marcspaz
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Posts posted by marcspaz
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I need to ask some questions... You are using a cable to go from the receiver audio out to the mic audio in, and set to vox? Correct?
If you simply remove the antenna cables from the duplexer, everything works (as well as to be expected without a duplexer, anyway)?
When you hook up the duplexer, the receiver receives a signal, gets a green light, but the transmit radio doesn't go into transmit mode, even though vox works fine without the duplexer? Or does the transmit light/display indicate that the transmitter is actually transmitting, but there is just no output from the duplexer?
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I think both radios need to be the same brand or use the same compander tech AND compander has to be enabled on all radios wishing to benefit from the tech. Otherwise, it sounds worse instead of better. It's been awhile since I read about it and I don't know anyone personally who uses it due to the compatibility issues.
- jwilkers, GrouserPad and WRHS218
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@WRUE951 that sounds good. I'm glad you've had good luck with them. My experience isn't terrible, just not ideal results. Since most of mine are EmComm related, I never really ran one for more than a few days at a time, and mostly left them off until I/we need to use them.
I know what you mean about learning the hard way. I struggled so much to avoid spending the money on a proper repeater that I probably spent 3 or 4 times more than if I just went for a regular repeater to start. I finally built a full-blown potable repeater system... it can do 2m, 70cm, crossband or act as a base station. It has a built-in 50 amp hr battery system and can run on solar or AC. Retail, it is about $17k to build, but thankfully some stuff was donated and I was able to get great deals on a used repeater and commercial VHF duplexer, which cut the cost down to about 10% of new/retail.
- SteveShannon and Raybestos
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I think it's great that they came up a solution, and as much as I love the KG-UV980P hardware platform, I would never use a KG-1000 nor a KG-UV980P as a full-time unattended repeater.
1.) As good as they are, they are not designed for continuous duty cycles or 24/7 operation.
2.) They may overheat or flat out fail with prolonged use.
3.) The transmit/receive isolation is not as good as a proper repeater, leading to desense issues.
4.) Audio quality and levels can be inconsistent.
5.) VOX or Carrier Operated Switching methods can introduce delays, distortions, and clipping.
6.) There is zero remote monitoring, diagnostics, or telemetry unless you engineer something yourself.
7.) Paired mobiles are extremely inefficient with regard to power consumption.
The only time I ever have or ever would use paired radios as a repeater would be for temporary field use and as an emergency backup (maybe). In an emergency, the FCC isn't going to ding anyone for not having the repeater ID on it's own, and for temporary field use the control operator is IDing the repeater every time they ID themselves... so an add-on device is really not needed.
- Raybestos, SteveShannon and WRYZ926
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11 minutes ago, WRDJ205 said:
Google is sending me to the same link as i found earlier ...
Repeater Duplexer 50W UHF 6 Cavity Duplexer SGQ-450D -
That's the one.
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2 minutes ago, LeoG said:
It's totally possible. The new one came nicely pack in a bubble bag surrounded by foam in a thin cardboard box. I just pulled it out and the old one that I'm storing in that box I checked the tuning screws and they are as tight as can be.
And here's the original one that I replace with the one sent by Btech. Looks like a different brand, probably the cheapest they could find until they found out you need to by them again.
That would be awesome to mess with for an afternoon. It's small, so it should be cheap to ship, too. If you want me to take a look at it, PM me and I'll send you my info.
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Just now, LeoG said:
Ya, thanks for the offer. Up in CT so kinda far to travel. But maybe I'll get sick of working up and take a couple days off and go visiting. Got people as far down as Florida and Texas I'd like to meet up with some day to make the imaginary internet friend real friends.
My son in-law just retired from the Navy (damn I'm old). He spent his last few years in Gronton, and lived in Preston. I still have family in Rhode Island and Florida too... funny coincidence. LOL
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2 hours ago, LeoG said:
No, directly from Btech. I ordered the repeater from them. They decided the duplexer was troublesome and sent me a new one already tuned to the GMRS spectrum. I removed the old and installed the new. I still have the old one, they didn't want it back.
I'd love to get my hands on it to see if it's just out of tune. You may have 2 good duplexers now.
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3 hours ago, LeoG said:
I would actually like to get one tuned to the frequency I use to see if it changes anything. Not planning on moving the frequency anytime soon so a hard tuned duplexer would be just fine. I would just remove the broad tuned one out of the machine and replace it with the single band tuned. Pretty simple operation. Probably less than 1/2 hour. That's about what it took me to do when I didn't know what I was doing, although not knowing what I was doing was just based on never had done it before. It's just removing some screws, swapping out the coax one for one and returning the screw back in place.
I think some companies will pre-tune them for you, but I would be concerned about filters with a more narrow filtering being shaken/vibrated out of adjustment during the shipping process. that may be why the first one you had didn't work so well.
I may have asked this before, but if you are anywhere near DC, I'd be willing to meet up with you to tune one, or at least verify one you order stays in tune after you get it.
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For those new to radio, and aren't a complete radio dork.... yet.... 12dB SINAD is a standard measure to describe receiver sensitivity. SINAD stands for 'Signal to Noise and Distortion'. This type of measurement is particularly useful for testing analog FM receivers. It represents the point where the desired signal is 12dB stronger than the combined noise and distortion. A lower input voltage at 12dB SINAD indicates a more sensitive receiver.
Receiver sensitivity is the ability of a receiver to detect weak signals. A lower input voltage (measured in microvolts or dBm) at 12dB SINAD means the receiver can detect weaker signals and still produce a usable audio output. A 12dB SINAD measurement of 0.25µV (about -118dBm, -119dBm) is pretty good. Most expensive radios are about 0.200µV (about -121dBm).
I looked at that SGQ-450D duplexer specs a few minutes ago. If someone is interested in buying one, while it's only rated for 50w, it actually looks pretty good on paper. 1dB insertion loss is great and both the suppression and isolation are on par with other mobile duplexers that are 3 times the price. Again, zero personal experience with this particular device, but it looks good on paper and @LeoG hasn't thrown it in the trash yet... so those are both good signs. LOL
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Due to there being a 5MHz spread between the uplink and downlink, you can make a custom duplexer that would be low loss and provide great separation, but you would have to have a pretty good understanding of electronics and how LC networks work.
I am unaware of any commercially available, but if there is one out there and configured to tolerate any reasonable power, it would likely be well over $3,000. I wouldn't be shocked if it was more like $5,000.
Actually, the repeaters available from companies like Midland are as expensive as they are, and have such low power, due to having a broad frequency duplexer that covers all channels. They tried to make them as efficient as possible without pricing themselves out of the market.
- WRDJ205 and SteveShannon
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I may have mentioned this earlier in the thread... but I think the FCC is 40 years too late in approving FM on CB. I'm glad a manufacturer stepped up and got the change made, but it's just too late.
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Have to say, I miss the hay-days. Back in the `70s and `80s (a little of the early `90s, too), I had an absolute blast on the CB. I had a base station and also a mobile in every car. My base setup had an ERP of 122kw. When I would fire it up full power, none of my neighbors could watch TV. One of the people closest to me said he was pretty sure my radio caused his refrigerator to hum. LOL
Compared to back then, it sure feels like nobody is using it.
- GrouserPad and WRTC928
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16 minutes ago, SteveShannon said:
I don’t think you have to be a ham to use the NTS. You just need to know hams who can help you use NTS.
This is correct. Anyone can send a message through the Hams. We do it al the time. It's our #1 task with ARES.
- Raybestos, FishinGary and SteveShannon
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2 hours ago, tweiss3 said:
In theory, its a $7+M idea that would likely just become space junk before it is used
For GMRS... 100% agree.
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1 hour ago, tweiss3 said:
While correct, I suspect the crowd-funding would be significantly short of the cost to get one up in near earth orbit. I wonder what space dust and the extreme temperatures would do to a "mobile" duplexer though.
When my old club put a repeater up, it cost over $7M. I doubt we would pull that kind of money together on crowd-fund... but it's fun to joke about.
I wouldn't put a mobile duplexer in orbit. That would be a disaster waiting to happen.
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Im not sure you can determine someone doesn't hold a license using this method. I only have two licenses under the FRN that my Amateur and GMRS licenses are under, but I have multiple FRNs. And unless you know what names are associated with my other FRNs, you're not finding them.
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11 hours ago, WRTC928 said:
If he was genuinely a moron, I'd ignore him, but he does actually know some stuff that I occasionally find useful. I just don't know why he's gotta be such a douche about it.
10 hours ago, OffRoaderX said:His stupidity and the stupid shit he says far outweighs the tiny nuggets of correctness that he randomly shits out.. and he has never said anything that 100 others here in the forum could not also tell you.
...just sayin...
I think the stuff that he gets right is either because he got lucky and said the right thing by mistake, or he researched the hell out of it and somewhat properly regurgitate what he read, but doesn't actually "know" what he is talking about. I think this, because right after he says something correct, he will follow-up with an explanation of why he right, but that explanation defies physics.
Imagine if I said that during certain conditions, if we shoot a GMRS single dang near straight up in the air, it comes back to earth and covers hundreds of miles in every direction. But then, instead of saying that it happens because signals can bounce off of planes, meteor showers, the moon or (more often than not) random weather anomalies... I say it's because the radio signal is so heavy, it's like launching a watermelon out of a giant slingshot. Its kind of like that.
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37 minutes ago, WRUE951 said:
Yea,, but SoCAL says hes an old man so he like us already went throught that stage.. He never grew up.......
What I don't get from SoCal is, he either says or has strongly implied that pretty much none of us know what we are talking about, always wrong, and a bunch of NotARubicon nut huggers (sorry, Randy. You know I love you).... and, he seems like he's always mad at us. So why the heck is he wasting his time and talent on this forum? I've asked him... but no response. Maybe it's like watching a car crash. Its so horrific that you can't look away.
Anyway Guest PG3, just ignore the stupid stuff he says and try to pull something useful out of it. Honestly, recording the experience if it continues to happen and then filing a police report with local PD isn't a terrible idea. You just need some proof it's happening and you may get some traction.
- PRadio, SteveShannon, AdmiralCochrane and 4 others
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You definitely got lied to. Every channel is free to use. No one owns a channel or has a channel allocated to them. Law enforcement almost never uses these channels for official business and when they do, you still have as much right to use the frequency as they do.
Most of the time, when FRS/GMRS is used by the government, it's not police. Its typically a civilian liaison acting as a go-between for U/SAR volunteers or volunteers working in support of some type of remote response to things like mass casualty incidents. I'm pretty sure you would know if there was a mass casualty incident close enough that you can hear another user directly.
- TrikeRadio, WRUE951, RayDiddio and 5 others
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30 minutes ago, Lscott said:
Yuck!! That's even worse than my guess on 75/80. It would fair to say using those antennas would be equivalent to a QRP radio with a full sized dipole. The testing you did should be impressed on Hams operating mobile. Some spend a fortune on those antennas to operate on the HF low bands.
I agree for sure. Anything under 20m is very hard to get communications out of while mobile. 80m and 100% equal to QRP, for sure. 100w in for less than 2w out. If you are actually moving, that makes it even harder. I have seen some guys spend $2,500 or more for some of these high-power screwdriver antennas, but it's pointless unless they have a mobile 1,000w amp. Even then, the 1,000w to the antenna on 80m would be like 150w-180w to a proper vertical antenna (not even a dipole). That antenna would be hot enough to cook on. LOL
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@Lscott I tested my screwdriver with a field strength meter and compared it to my dipole and my dedicated whips. On 80m, I only had a 1.8% efficiency rate. On 40m, it was about 30%, and on 20m it was about 50%.
I switched over to Diamond mono band 86.6" whips and retested. The dedicated whip was still less that 2% efficiency rate on 80m. However, on 40m, it was 50%+ and 20m was almost 90%.
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5 hours ago, Jaay said:
Jack ?? Huh?
I guess not. Jack is the guy who submitted the Petition for Rule Making. Some of your posts lead me to ask the question.
Repeater Box Build: Attempt 1
in Technical Discussion
Posted
I am thinking you need to swap radios on the duplexer ports. Like, I think they are labeled backwards. It would make sense that the case of the HT is letting enough RF leak in to trigger a receive light, but there is not enough of a signal to create usable audio output to trigger the vox operation.
If its not labeled wrong and it is wired correctly, you could just be washing out the systems due to being to close to each other and too close with the test handheld. I have seen some HTs so sensitive to RFI from other HTs, that we had to separate them by 75 to 100 yards before the RFI and desense was small enough for the radios to work correctly.