Charles Scott wrote: > Not exactly the kind of comments I'd expect from you. I didn't notice > which band it was for this unit, but from 440 up the little mobile > duplexers can be pretty small and work well for low-power applications. > Also, why are you worried about shielding? I believe the radios in the > repeater chassis have their own shielding, and what leakage would you > expect from one of the small mobile duplexers? Considering the possible > problems that have been reported with the jumpers inside the case, it > may have been an improvement!
Sorry, was in a horribly bad mood last night. Big escalated issue at work. Still going on, but now we're down to "Nate will work all weekend to make sure the problem is fixed." instead of conference calls with angry C-Level execs. (I wouldn't mind so much if I hadn't audited these configurations and then someone copied the wrong one to all of the production systems instead. Sigh. 40,000 phone lines worth of teleconferencing equipment misbehaving all over the country is not a good way to spend three days, in case anyone's thinking about a career in telecom technical support. It's also a great way to miss participating in Field Day, for the most part. Sigh. Oh well, I'll get a bunch of OT, and maybe that'll pay for an ID-1. GRIN! There's always a silver lining, right? Heh heh.) I shouldn't have hit "send" on that one. But since we're here, I'll be nicer... and explain better... > Don't know what you have against the smaller mobile duplexers, but I've > used them in a number of applications and they work just fine--good > rejection (for these power levels), not much more loss that a full sized > duplexer, and certainly no leakage. They just don't handle much power. Real shielding using grounding strips, etc... between sections is what a real repeater (GE) has. Or individual RF shielded boxes for each section if they're on the same board (Moto). These "mobile in a box" repeaters are problematic at high RF (commercial) sites. They're "okay" but it sure would be nice if Icom would spend an additional $100 on sheet metal work to block the two sides from each other. As far as the mobile duplexer... I guess they're "okay", I just don't build with them. 1/4 wave on UHF just isn't that physically big, and fits fine in most cabinets. VHF, is a pain, and most mobile duplexers won't handle our 600 KHz typical (now California is doing 400 KHz) splits very well. > Sorry, Nate, just don't see a real problem with this on the surface as > long as it was physically well done. Understand. It's just MUCH easier to "over-do-it" a bit on the duplexer and cabling, etc. Plus... all these reports that cruddy cabling may have been used internally really chaps me badly for a box that costs $2000 or more U.S. -- these things should be brick you-know-what-houses for that price. How much margin in Costs of Goods Sold (COGS) is there, in packaging two $500 mobiles in a metal box? A lot. Not including R&D, there's probably at least $1000 profit in these boxes. (Because the mobiles don't cost Icom $500/ea to put in there, anyway.) I very much looking forward to seeing the rumored "other" repeaters that people are working on. Keeping one of these things alive on a high-mountain site complete with trips to investigate problems is a $100 round-trip issue every time it happens at today's fuel costs. While this might argue that it's a good idea to replace these cables, etc... now... when it's "cheap"... it bugs me to no end that Icom isn't just upgrading them in later "versions" of the repeater. Adding proper TX to RX shielding (a metal wall between the two rigs with fingerstock on top, as a bare minimum?) etc, is too easy to ignore. It's a bolt-in fix that can't cost more than $15/repeater, including "development" costs to pay an engineer to draw it on a CAD program. Others will eventually fill the void Icom has in their repeater engineering skill-set... I was just grumpy that someone stuffed a mobile duplexer inside too... in a box that already has reported leakage, and other problems. Think RF can't get through that 4" hole where the fan is, for example? That's not "shielded". The repeater "RF packaging" is a joke. It'll get better. Either Icom will step up, or someone will knock them off the perch, but it'll get better... I'll hold out hope for that, anyway. Nate WY0X
