gman1971

Sorry, been out for a while. So, I updated the inventory, and added three new XPR 6550, this time for the VHF variants. Excellent radios for DMR on HAM.

https://docs.fcc.gov/public/attachments/DA-21-309A1.pdf

LOL cheap S.O.B. hahaha.... Their NX series offers the option to chose two out of three digital modulations on these radios. So, for such a premium radio like the D74 one would think they could add the options... but... oh well... G.

Yes! Totally, I had at some point 4 TH-F6a... and it was a huge letdown to see they went with D-Star and not with DMR, which I think its far more popular than D-Star... considering every digital CCR ever made since 2015 is been DMR... plus the top dogs like Motorola use DMR... So, if they do, I probably will get one too, but ATM I am so tied up in Motorola right now, that its hard to give up some of the bells and whistles these Moto radios have, especially hard to give up is RX Audio leveling... the only way it would happen is if Kenwood added a SFR to the TH-D74a... but... I doubt it. G.

If it can't hear that good with a high gain antenna, it would seem like the 1000G lacks filtering and uses a direct conversion receiver, and its desensing. Just perform an ISO-tee on the radio.

Yes!, the SFR is certainly a nice thing. ERDM is called in Motorola terminology. The SLR repeaters have the option, but you need to get the entitlement. TETRA also has an SFR, RX on TS1 and TX on TS4 The downside of NXDN is that you don't have timeslots. So you can't really TX and RX at the same time on the adjacent channels, not without blowing the receiver. The timeslots allow for TX/RX to be done 90ms within each other so the receiver doesn't blow up. With a time based multiplexing, you can cram more concurrent channels (adding more timeslots), provided you can satisfy the data stream. Nothing equivalent exists on NXDN. G.

True, in the end, they all have little quirks, for sure, but some have more than others! (and some are just plain WTF) The EVX CPS was radically different to anything else I've used up to that point, I still think its better than the Moto CPS for some things, for others, not so much! The EVX (not VX) programming cable I got from antenna farm didn't work for me, so I had to get the FIF-12 for all my EVX radios... G.

@tweiss3 Nah, I had enough of those CCRs and their terrible CPS. I had 6 of them in total at some point, down to just two MD5 and a 578... all for sale... btw... @LScott, yep, right there with you. Its funny when Motorola users complain about the issues on the Motorola CPS .... I keep telling myself, "looks like you had an easy life, bud... try the AnyTone...." yep... G.

An X-29 with forward swept wings!! Man, nice choice... G.

Yes... yes, I know, wish it was 1 GigaWatt, but its only a mere MegaWatt... oh well... G;

Sure, why not! LOL... glad you liked it! G. EDIT, I also made a mistake... as always... its 1 MEGA watt, not 1 GIGA Watt... oh well.. G.

Well, not really, and 1000 kW is only 3dB more than 500 kW, so... The tower, with 1 MegaWatt @ 490 Mhz (roughly around where UHF TV station transmit) is a whopping +90dBm; so, if you calculate the attenuation/loss in free space , since the tower is 1000 feet high in the air, and there are no terrain LOS obstructions within 4 miles, most likely.... So, you get roughly a -96dBm @ 490 Mhz attenuation/loss of those firebreathing +90dBm over a 4 mile distance, so, these CCR receivers are seeing a massive -6 dBm signal on the front end, only a few MHz off the channel frequency. In comparison, your superduper 50W GMRS mobile is putting roughly +46dBm, so, at the same 4 miles, given roughly the same -96 dBm attenuation @462 Mhz, the CCR receiver is seeing your GMRS mobile as a faint -50 dBm, on frequency, but a few MHz away there is this firebreathing signal that will completely obfuscate the desired signal you're trying to listen. And if that 1 MW transmitter is on the "right" frequency, to mix with the 1st IF stage frequency (for the Superhets) to create IMD, then you'll have all sorts of reception issues, or no reception at all. Basically, you're trying to hear a nylon string classical guitar, without amplification, over a pipe organ playing at full power. G.

Awesome! Thanks Michael, ... and yeah, totally above freezing, and no snow... we are covered in like 4 feet of snow around the house here!! In Wisconsin hahaha... G.

Well, you actually did have one: The XPR6550 has a very reliable RSSI mode built in. I own several of those radios, all tested with a service monitor, all accurate within a dB to the measured signal. The 6550 gives an actual numeric RSSI readout, not the bars, which are useless unless they are calibrated to a known dB reading. Reading the bars is like eyeballing things out... A 2 and 4 bars out of 5 is a very high noise threshold, but 2 or 4 out of 20 bars is a very low noise threshold. Without knowing the noise threshold on your site its impossible to really know the reasons why the 7350 didn't outperform the other radios. Also, I would've used an SDR cascade to determine the strong off band signals, TV stations, etc... those glow in the dark for an SDR... Thing is, If the noise at your site was really high, it doesn't matter what radio you use, having an effective sensitivity of -120 dBm is useless if the lowest signal you can hear is -96dBm, which in turn, means that the frequency you are using is not suitable for long range comms. Like I've said, you should've done a site analysis, determine which GMRS frequency had the lowest noise threshold, and probably use that. Again, if the noise level RSSI is -96 dB, literally, it won't matter what radio you use, a BF-888s would've probably matched the XPR7350 just fine, and for 9 dollars... Most of those Motorola radios edge the CCRs when he noise threshold is LOW, AND there are strong off band interference, the XPR7550e I have all measured better than -120 dBm effective sensitivity, with a noise floor of -126 dBm. Also, figured I'd say this, but a 50W mobile on the adjacent channel doesn't really qualify as a strong interference. A 250kW TV station on a 1000 foot tower, a few MHz away that is a real interference for a superhet. G. EDIT: Point I am trying to make is that no radio can bend the laws of physics, but the high quality radios are better when the conditions are favorable to be better. The same thing applies to astrophotography, and there are times in which it doesn't matter how many filters you use, or how expensive your equipment, you simply can't picture things b/c the light pollution is, simply put, too strong and too wideband for anything to be effective, especially with the newest LED street lighting that is full spectrum, making most light pollution filters, which block things like Sodium lights etc... those are useless when all you have is LED street light.

Well, the 1400 foot tower that is placed ~1.5 miles from my house has at least one 250kW UHF TV station on it... 500kW is just 3dB more than 250kW... so...

For house, I found the Laird FG4500 to be really really good. For the car, I found that an NMO was the way to go, so I removed the factory sharkfin/antenna and placed a GMRS antenna there. Performance went through the roof (no pun intended) with a 6 inch 1/4 wave. G.

Yes, buy the heliax with the right angle already as part of the end connector. Every adapter you add, is a potential impedance mismatch, and your TX range will go down the tubes rather quickly. G.

Michael, Before anything else is said, thanks for doing this. I am rather surprised the range you got with the XPR7350. Did you had a chance to measure signal RSSI at every point? Did you measure site noise threshold? I would've liked to know what the RSSI readings from the 6550 were. G.

This is where RX Audio leveling in Motorola XPR gen2 radios solves this problem once and for all.

Basically, what a dummy load is. 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.

Yep. n1das summed it up pretty much how it is. Nice write up. G.

These are great radios. I wish I would've found them sooner, and that they offered them with a bit more features, I would've probably used them over the XPR7550e and SL7550 for floor intercom stuff... but... G.

Well, I am sorry if I disagree with this, but NanoVNA is hardly an advanced piece of equipment. Takes watching one Youtube video to know all you need to know about it for a beginner... And my first "SWR meter" was a Times T100+ vector analyzer (still have it) I remember the needle SWR meter thingies at some ham meet up and I was like... yeah... there has to be a better way... and indeed there was. G.

The Retevis seem like a scam... Just get used DTR G.