gman1971

I'll add my 2 cents for Corey and JohnE regarding the 90 degree coax connectors.  I am retired from the cable tv industry and I will tell you that we started using the 90's for cable management benefits but soon found out that we were experiencing far too many signal failure and signal strength loss issues to continue on with them.  We ended up doing a massive rewire to remove all existing 90 degree coax fittings in the plant. My hands experience with those issues says I will never install a 90 degree fitting in any of my radio coax connectivity.  Too many opportunities for failure and equipment loss.
Craig

Yeah man - I love the nanoVNA, and I got the cheaper one. Pretty sure I got the 4.3" screen, but it'll only sweep up to 1.5ghz - there's a 3ghz one thats a little more expensive, still under 100 bucks though. Definitely not nearly as good as a lab grade instrument, but it's also not 10 grand. You can also connect to a computer and do everything from there - I'm looking to get that going at some point.
 
Ohms vs SWR - yeah, if you're tuning for a single frequency or very tight range and you tune for 50 ohm impedance - you're going to have a low SWR just by default. The opposite doesn't hold true. You cah measure a low SWR and still have an impedance mismatch. I forget exactly how that works but I seem to remember that bieng the case?
 

If your feed-line loss is high, your SWR appears artificially low. Add enough loss and ever the worst case real-world SWR will appear perfect at the radio.
 
 
Michael
WRHS965
KE8PLM

Oh, the Surecom shill... seriously, get a NanoVNA v2 with a 4.3 screen to measure SWR. Tune your antennas to 50 ohms, not to the lowest SWR (return loss).
 
G.
 

The Motorola CDM750 or CDM1250 are surprisingly good radios with very good receivers.  The 1250 might be a tad better b/c you have more than 4 channels.. but...
 
G.

If only for GMRS, I'd go with one of the second-hand commercial mobiles, like Kenwood TK-860, TK-880, TK-8180 or similar (like 8102), or with offerings from Motorola. Much much cheaper, and by a lot of circumstantial evidence, perform better.

Thanks.  I just made a few minor edits.  Maybe the next thing for me to do is write up a DTR/DLR programming overview and explain a lot of the workings.
 
Programming the DTRs and DLRs is often cryptic and befuddling to new users.  No programming is needed to use DTRs and DLRs right out of the box at the factory default settings.  Customization of features and settings requires the CPS.  Some settings can be changed without requiring the CPS.  Programming the legacy DTR410/550/650 is cryptic and the DLR programming cleaned up a lot of things and made it a little less cryptic.  The DTR600/700 models program like the DLRs.  I suspect the DTR600/700 models use the DLR's code base.  I am not surprised Motorola adopted the DLR way of programming going forward.
 
The DTR600/700 models are backward compatible with the legacy DTRs but it requires some understanding of the differences.  When I owned DTR650s, DLR1060s, and DTR700s, I had them all working with each other on public and private talkgroups.  The DLRs and DTR700s added a 4 digit Profile ID Number (PIN) feature which the legacy DTRs don't have.  I had my DLRs and DTR700s working with each other on Profile ID mode channels.  The PIN feature allows you to take DLRs right out the box and set a 4 digit PIN to secure all channels in them without requiring the CPS.  With the legacy DTRs, the only way to secure them was to use the CPS to program private talkgroups into them.  Motorola made it insanely easy for DLR users and DTR600/700 users to secure their channels in radios right out of the box without needing the CPS.
 
A lot can be learned about them by downloading and installing the CPS and exploring the DTR and DLR programming.  The CPS has default DTR and DLR templates to work from so you don't need to read a radio first to use the CPS and play around with the programming.  The latest CPS version is R08.02 and programs all of the older models too.  You don't need an older version of the CPS to program an older radio.  Just use the latest version of the CPS.

If you live in a very rough terrain area, high gain will be very detrimental. I found that going with lower gain (as in Laird FG4500 unity gain antenna) gave me overall better performance than a 4dBd Hustler G6.... so keep that in mind.
 
G.

LOL, 1.5 kW?  hahaha, that's basically centimetre band radar!! just make sure you're several hundred feet under the antenna when you key that thing...  
 
3 1/2 years!! and counting... but... who is counting?
 
G.

Get a NanoVNA v2, a dummy load and test every segment of cable in the system, measure for impedance, if any given segment of cable is not 50 ohms (or close to it ) then its time to buy better cable, test every connector as well. I learned this the hard way, so now I only buy USA made Harbor Industries RG400, with MILSPEC silver plated N-connectors or Mini-UHF (since all my gear is Motorola) for short patches, and for mobile operation. Quality RG400 (or RG142 if you plan on permanent install) cables that are properly made will have impedance well within 1 Ohm of 50 ohms, at any frequency in the UHF range, will vary slightly depending on the length of the cable) 
 
You can measure adapters with a dummy load and NanoVNA... Measure the dummy load impedance directly, then place the adapter between NanoVNA and the dummy load, if the impedance changes by more than 1 Ohm, time to buy a better adapter. I recommend silver plated, and/or trimetal adapters only, nothing with chrome. And before I forget, don't expect PL259 to hold 50 Ohm impedance above 300 Mhz, they are severely lacking above 200 Mhz, so my advice, ditch the PL259 stuff, and go with N.... otherwise, the impedance mismatch will thwart any chances of having a decent system.
 
G.

Could it be the squelch settings?  Some radios have fairly complex settings that can only be changed in software.

You're welcome, NCRick.
 
Which one of the radios you asking?
 
The HT1250 software is been EOL for a while now, I am sure it can be found on eBay for very cheap. The CPS you probably want for the HT1250/CDM radios is called "Professional Radio CPS" and the version you want is probably R06.12.02, which is what some of the people I know use while still allowing for 25/20 wideband operation. These are really great radios, most people don't think much of those, but they are absolutely bargains... and the receivers are really really good. They make those in a variety of frequencies, from 29 MHz all the way to 800 MHz I think.
 
The XPR6550 is a FM/DMR radio, and the sotware used is called MotoTRBO CPS16 which is EOL, and can be found on eBay for very cheap, although you can also get a Motorola subscription which will get you 3 years of firmware upgrades for all the newest MotoTRBO radios, etc... probably not what you need for just GMRS... I personally find CPS16 a far better product than the newest CPS 2.0 contraption.... which IMO, is a huge step back, almost to the point of being as clumsy as the clunky-a$$ ancient Professioan Radios CPS from two decades ago... so...  The cables for XPR6550 portables runs from 30-80 bucks, depending on if you want a genuine cable or the BlueMaxers49 eBay one, which works too... I have both... so if you just need to get by, the 39 dollar one will work.
 
The EVX-539 CPS the software was free from VSOL (Vertex Standard Online) It can still be found if you look around, and worst case you just buy it for a few bucks. There are two versions of this radio, which use different CPS, so, for the older segment LCD version you'll need CE142 and for the newer, Dot Matrix display you'll need CE151. The cable is the same for both, however, you'll probably need to get a genuine FIF-12, b/c I've tried a couple of the cheaper ones and none worked... so, the FIF-12 will set you back ~100 dollars, but its guaranteed to work. The EVX-539 have a fairly good receivers, but IMO, after trying the Motorola Professional Series, including the HT1250/CDM750 combo, I think the HT1250 is a better radio in terms of overall FM performance, easier to tune and I think better audio. I also found that the CDMxxxx mobile radios to be absolutely spectacular in terms of receiver performance, too, on par with the mighty XPR5550e I've ISO-teed... so... if you don't need digital, my vote goes to the CDM750/1250/1550 mobiles and for the HT750/1250/1550 portables (walkies) (The nomenclature is 750 = no screen, 1250 = screen with limited keypad, 1550 = screen with full numeric keypad) 
 
EDIT:
 
I think there is an option to make an HT1550 FPP, (front panel programmable) but I would ask around for more info. The 1250 not sure if there is an FPP since it has a minimal set of keys), the 750 is just a rotary switch with a couple of buttons, so that one you'll need the CPS. 
 
I've seen on Youtube people doing FPP with the 6550, so I know there is a way to make it FPP, but I am not sure how to do it.
 
The EVX-539 I don't think there is an FPP option, or at least not that I am aware of, so you'll need the CPS for this radio.
 
Good luck!
 
G.

This reminds me the good old days of the cb radio era, rough but functional. Experimenting with everything

@gman1971 thanks for your post.  I have always been a fan of Motorola.  With the radio mentioned, am I able to program this via the keypad or through inexpensive easy to get software?  I found your information helpful and concise.

If you just want to give the radio hobby a try then just get a Baofeng BF-888S: its a 9 dollar radio. It programs with CHIRP, and the cable is like 9 dollars: in short, it should be the simplest and cheapest thing to get going. If you don't like the hobby, or for whatever reason you decide this is not your thing, then you can smash the thing with a hammer, set it on fire, blow it up with tannerite... and not much will be lost. All other CCR radios mentioned here, the Wouxun, the Retevis, et. all, all those will have similar low performance to the Baofeng BF-888S, except they cost a ton more (rip off??) and are equally bad in terms of receiver performance. Yes Yes... I know... here are the buzzwords to be aware of: Superhet, Hyperhet, Megahet, Turbohet... etc all those buzzwords are designed to sell overpriced cheap radios without the most important component: a proper TUNED FRONT END (to filter all the unwanted signals out there) which is what most LMR Part 90 radios will have... so the radios will work inside Best Buy and not blank out due to all the electronic noise present.
 
But, OTOH, if you do like the radio hobby, the next radio should be a quality LMR radio, not a cheap china radio (CCR). Personally, I would chose a Motorola, the HT1250 is a fairly inexpensive radio, or the Motorola XPR6550, or the Vertex Standard EVX-539 etc, but also Kenwood, or Icom LMR radios are pretty decent too. Remember that GMRS is NOT Ham radio, so, you don't need a VFO, nor the ability to transmit in 100 bands, or in fifteen different modulations. All you need for GMRS is a FM UHF radio that transmits and receives from 462.5 to 467.8 MHz, can store at least 22 channels, do repeater offsets and have the ability to set PL tones. That's about it. Most commercial grade radios will suit your needs.
 
G.

If you just want to give the radio hobby a try then just get a Baofeng BF-888S: its a 9 dollar radio. It programs with CHIRP, and the cable is like 9 dollars: in short, it should be the simplest and cheapest thing to get going. If you don't like the hobby, or for whatever reason you decide this is not your thing, then you can smash the thing with a hammer, set it on fire, blow it up with tannerite... and not much will be lost. All other CCR radios mentioned here, the Wouxun, the Retevis, et. all, all those will have similar low performance to the Baofeng BF-888S, except they cost a ton more (rip off??) and are equally bad in terms of receiver performance. Yes Yes... I know... here are the buzzwords to be aware of: Superhet, Hyperhet, Megahet, Turbohet... etc all those buzzwords are designed to sell overpriced cheap radios without the most important component: a proper TUNED FRONT END (to filter all the unwanted signals out there) which is what most LMR Part 90 radios will have... so the radios will work inside Best Buy and not blank out due to all the electronic noise present.
 
But, OTOH, if you do like the radio hobby, the next radio should be a quality LMR radio, not a cheap china radio (CCR). Personally, I would chose a Motorola, the HT1250 is a fairly inexpensive radio, or the Motorola XPR6550, or the Vertex Standard EVX-539 etc, but also Kenwood, or Icom LMR radios are pretty decent too. Remember that GMRS is NOT Ham radio, so, you don't need a VFO, nor the ability to transmit in 100 bands, or in fifteen different modulations. All you need for GMRS is a FM UHF radio that transmits and receives from 462.5 to 467.8 MHz, can store at least 22 channels, do repeater offsets and have the ability to set PL tones. That's about it. Most commercial grade radios will suit your needs.
 
G.

Pretty badass radio... its a Part 90 radio. Just keep it and use it for GMRS. It will serve you well... certainly a great starter radio over the CCR garbage.
 
G.

A 4? Where did you get these antennas from?
 
If these antennas indeed had a 4:1 SWR, like you claim, all my XPR 6550s would've probably be blown long ago, and not have simplex radio-to-radio range of almost 3 miles, ground to ground ... I have a bunch of those in service, and these (and IF these are genuine Motorola) they should read around ~1.67 : 1 at ~462.6 Mhz...
 
You really need a better SWR meter, that sw33 thing is a dog... My choice is NanoVNA v2.0, with N connectors. Its not an HP/Agilent, etc, but at the cost, and size, is good enough to suit most light duty stuff.
 
G.

two CDM750, a 29 dollar programming cable, a 10 dollar repeater link cable, a used UHF duplexer, a few feet of RG213 cable, two 10 feet metal pipe sections, and a Laird FG4500 UHF unity antenna atop those 20 feet.
 
That will give you one of the best FM GMRS repeater options, for a fairly modest price tag.
 
G.
 
EDIT: Forgot the 20 Amp 12VDC power supply.

If you just want to give the radio hobby a try then just get a Baofeng BF-888S: its a 9 dollar radio. It programs with CHIRP, and the cable is like 9 dollars: in short, it should be the simplest and cheapest thing to get going. If you don't like the hobby, or for whatever reason you decide this is not your thing, then you can smash the thing with a hammer, set it on fire, blow it up with tannerite... and not much will be lost. All other CCR radios mentioned here, the Wouxun, the Retevis, et. all, all those will have similar low performance to the Baofeng BF-888S, except they cost a ton more (rip off??) and are equally bad in terms of receiver performance. Yes Yes... I know... here are the buzzwords to be aware of: Superhet, Hyperhet, Megahet, Turbohet... etc all those buzzwords are designed to sell overpriced cheap radios without the most important component: a proper TUNED FRONT END (to filter all the unwanted signals out there) which is what most LMR Part 90 radios will have... so the radios will work inside Best Buy and not blank out due to all the electronic noise present.
 
But, OTOH, if you do like the radio hobby, the next radio should be a quality LMR radio, not a cheap china radio (CCR). Personally, I would chose a Motorola, the HT1250 is a fairly inexpensive radio, or the Motorola XPR6550, or the Vertex Standard EVX-539 etc, but also Kenwood, or Icom LMR radios are pretty decent too. Remember that GMRS is NOT Ham radio, so, you don't need a VFO, nor the ability to transmit in 100 bands, or in fifteen different modulations. All you need for GMRS is a FM UHF radio that transmits and receives from 462.5 to 467.8 MHz, can store at least 22 channels, do repeater offsets and have the ability to set PL tones. That's about it. Most commercial grade radios will suit your needs.
 
G.

New guy from N.W. Indiana. Just recieved my GMRS. I'm here to learn..
Wrkp702

I tune for the lowest return loss at 50 Ohms. Which is never the same point where the lowest return loss actually is.
 
G.
 

The 5.5 dB claim is, simply put, not true. (also, if you don't see dBd or dBi its probably fake as well) That TRAM1173 (or MXT26) antenna probably has less gain than a simple 1/4 wave NMO, given the cheap coils used, and being only 2 elements, with insufficient phasing element separation between them (gain in collinear antennas is achieved by increasing the distance between the phased elements) not a chance in he11 it has 5.5 dBd... well, unless decibels dBs overseas are measured differently than in the rest of the world... that is.
 
For comparison, a real world 5.5dBd gain is what a 4-bay folded dipole has, which is a massive antenna, and coincidentally, it costs a lot of $$$$$...  too.
 
IMO, and in my experience, for a car install, a simple 6" inch NMO antenna cut to GMRS frequency will work absolutely great, as measured.
 
G.

I would test simplex, portable-to-portable, ground to ground, anything else tested with repeaters is doomed to succeed. From my house, I can hit every GMRS repeaters within 25 miles with my BF-888s the same way I can with my XPR7550e, which would make the 888s an amazing radio... but when actually doing simplex, I am lucky if I get more than 1/3rd of a mile with the 888s in suburban terrain.
 
Yes, the S24 is a nice little radio, but again, testing anything with repeaters is doomed to succeed.
 
I would use the 6550 RSSI meter to measure actual signal strength. The 6550 can be used to calculate site noise threshold as well.
 
For the XPR Gen2s you can easily remove the rear cover and put a Hirose to SMA adapter in there, that is how I run ISO-tee tests on those radios.
 
G.

In fairness, I'm going to be base-lining the units to meet advertised factory specs. I don't want these to be some type of "Super" units that have been tweaked beyond what the typical buyer would find in a used unit online.
 
They'll be tested to perform to spec, and guaranteed to be fine examples of what's available out there in the Part 90 world of used radios.
 
They will all have up to date Firmware, and I'll be using standard CPS software with 25 kHz Wideband entitlements. I hope to finish things up this weekend, and I'll ship them out to mbrun early next week.