And what frequency?
----- Original Message ----- From: "Merrill" <[email protected]> To: <[email protected]> Sent: Thursday, January 28, 2010 9:23 PM Subject: Re: [Repeater-Builder] Re: VHF Vari-Notch Duplexers - 2" x 2" x 4" ??? > Next question > > what channel spacing are you tuning them for ? > > Merrill > KG4IDD > > On 1/28/2010 8:56 PM, tahrens301 wrote: >> Hi Merrill, >> >> Yep, that's what the label says. >> >> Now, gotta figure out why they aren't >> living up to specs. >> >> Tnx >> >> Tim >> >> >> >> --- In [email protected], Merrill<kg4...@...> wrote: >> >>> Tx-Rx model 28-41-05 "Vari-Notch" pseudo-pass, notch >>> duplexer. >>> This is the appx two RU duplexer for wide split repeaters, >>> Comprised of five of the two inch square cavities. >>> Tx-Rx manual says 2.5 mhz spacing. >>> Tag says Tx 1.5 dB insertion for 76 dB isolation, and Rx is 1.1 dB for >>> 110dB(Tx is 76dB at Rx and Rx is 110 at Tx) >>> Three cavities on Rx, two on Tx. >>> >>> >>> >>> On 1/28/2010 8:28 PM, tahrens301 wrote: >>> >>>> Hi Rob, >>>> >>>> Sorry, I forgot to put the model number in the original >>>> posting! >>>> >>>> It's 28-41-05 >>>> >>>> It has 3 of the blocks in the TX line, and 2 in the >>>> RX. It's in a 2 1/4" thick rack panel. >>>> >>>> I opened one up, and it looks like a helical resonator >>>> with a silver slug that goes in and out, and the BNC >>>> connectors have a loop that is 90 degrees to the larger >>>> coil and has an air variable cap to ground. >>>> >>>> thanks! >>>> >>>> Tim >>>> >>>> >>>> >>>> --- In [email protected], "Rob Lee"<rob@> wrote: >>>> >>>> >>>>> The duplexer that you have may not be a "Vari-Notch" unit. Your >>>>> description >>>>> sounds like a "30 series" unit (Model number will start with a 30 e.g. >>>>> 30-36-01A) >>>>> >>>>> The 30 series VHF duplexers are specially designed to work with >>>>> repeaters >>>>> that exhibit problems when connected to high selectivity duplexers. >>>>> This >>>>> design uses three standard notch type filters on the transmitter side >>>>> which >>>>> provide excellent noise filtering while maintaining a relatively low >>>>> VSWR >>>>> over a wide frequency range. This helps minimize transmitter >>>>> sensitivity to >>>>> cable length between the duplexer and the transmitter and also reduces >>>>> the >>>>> potential for transmitter spurs. >>>>> >>>>> The receiver portion of the duplexer incorporates three pseudo >>>>> bandpass >>>>> filters to give isolation to the transmit carrier and reduce >>>>> interference >>>>> and intermodulation caused by other nearby transmitters. >>>>> >>>>> Because different types of cavity filters are used for the transmit >>>>> and >>>>> receive sides of the duplexer, it is important that the correct model >>>>> be >>>>> used. Model numbers are different for units designed for either the >>>>> transmitter higher or lower than the receiver frequency. >>>>> >>>>> I have tuning instructions if this sounds like the unit. >>>>> >>>>> Rob K7TGU >>>>> >>>>> >>>>> ----- Original Message ----- >>>>> From: "tahrens301"<tahrens@> >>>>> To:<[email protected]> >>>>> Sent: Thursday, January 28, 2010 15:37 >>>>> Subject: [Repeater-Builder] VHF Vari-Notch Duplexers - 2" x 2" x 4" >>>>> ??? >>>>> >>>>> >>>>> >>>>> >>>>>> Well, I thought this thing was tuned up, >>>>>> but obviously something is wrong. >>>>>> >>>>>> These are a set of the 2x2x4" cavities... >>>>>> have a plunger in the front, and a variable >>>>>> cap adjustment on the back. Also, a pair of >>>>>> BNC connectors on the capacitor side. >>>>>> >>>>>> The plate says Duplexer Vari-Notch, >>>>>> 147-174 >>>>>> >>>>>> It also implies that the TX has a 1.5dB >>>>>> insertion loss, but darned if I can get >>>>>> only about 4.5. >>>>>> >>>>>> I've talked to the guys at TX/RX, and they >>>>>> are looking for a book on them, but nothing >>>>>> yet. >>>>>> >>>>>> Anybody have any tuning instructions/info on >>>>>> them? >>>>>> >>>>>> The plunger is marked 'pass low', and the cap >>>>>> is reject high. Pretty much self explanatory, >>>>>> and they tune ok, but the insertion loss is >>>>>> higher than it appears it should be. >>>>>> >>>>>> Thanks, >>>>>> >>>>>> Tim >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> ------------------------------------ >>>>>> >>>>>> >>>>>> >>>>>> Yahoo! Groups Links >>>>>> >>>>>> >>>>>> >>>>>> >>>>>> >>>>> >>>>> >>>> >>>> >>>> ------------------------------------ >>>> >>>> >>>> >>>> Yahoo! Groups Links >>>> >>>> >>>> >>>> >>>> >>>> >>> >> >> >> >> ------------------------------------ >> >> >> >> Yahoo! Groups Links >> >> >> >> >> > > > ------------------------------------ > > > > Yahoo! Groups Links > > > -------------------------------------------------------------------------------- No virus found in this incoming message. Checked by AVG - www.avg.com Version: 9.0.733 / Virus Database: 271.1.1/2654 - Release Date: 01/28/10 14:36:00
