• Anyone know if this is an okay one for 5 MHz spilt? ? I need at least 80db of notch (isolation)
• Supposedly, it's a Moto. I'm shopping for one.?

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I don’t have one to test, I’m a bit suspicious of any duplexer of that design that claims to work across such a wide frequency range (406-500 MHz).? For starters, the interconnect cable lengths would naturally need to be varied across such a wide range to avoid degradation at frequencies far-removed from the optimum center.? Then, the tuning of those resonators is done by loading them at the hot end via slugs.? Generally the more loading, the lower the Q, so I’d be particularly concerned about performance at the low end of the 蝉辫别肠’别诲 range.? If anyone has one of these units surplus and would be willing to loan or sell it, I’ll put it through its paces on the VNA.

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A comparable, and very common, 6-cavity “mobile” UHF duplexer was the RFS/Celwave 633 series.? Those would typically do about 90 dB notch depth when used within its 蝉辫别肠’别诲 range at a 5 MHz split.? RFS used to OEM the 633 for Motorola as well (TDE-7780A was the 450-470 model), but RFS no longer manufacturers them.?

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Attached is a sweep of a 450-470 MHz model 633-6A-2 operating “in band” (GMRS) that should give you an idea of what to expect; I’m not saying that the Motorola/Combilent DSCP10725 will perform the same, just giving you an example of a similar unit.? The ham-band version covered 406-450 MHz (model 633-6A-1), I have a few of those NIB if you want me to sweep one.

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??????????????????????????????????????????????????????????????????????????????????????????????????????????????? --- Jeff WN3A

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I do know these can be had for much less than the nearly $400.00 I see that one going for.

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Gregg Wardlow

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