If you want it to work well, then replace the Q2220E with a better duplexer.
If you are willing to accept a compromise in performance, then continue using it and add extra cavities onto it. ------ Original Message ------ Received: Wed, 25 Mar 2009 04:40:17 PM PDT From: AJ <[email protected]> To: [email protected] Subject: Re: [Repeater-Builder] Re: Sinclair Q2220E > Any suggestions for improving the situation with our existing Q2220E > duplexer? > > We could turn the P/A down even further, but there's not much more room to > work with with this 40 watt P/A from it's current 25 watt level without > causing spurs... > > > > > On Wed, Mar 25, 2009 at 3:44 PM, John J. Riddell <[email protected]>wrote: > > > *Re the Sinclair RES-LOC Q2220E Duplexer, they make a much better > > version, * > > *the Q2330E model.* > > ** > > * We use one here on VE3KSR, 146.970* > > ** > > *It has 100 Db of Tx - Rx isolation at 500 Khz and midband isolation of > > 55 Db* > > *as opposed to 30 Db in the Q2220.* > > ** > > *Power rating is 350 watts on each unit.* > > ** > > *The Q2330E** has three "cavities" on each side.* > > ** > > *73 John VE3AMZ* > > ** > > ** > > ** > > ** > > ** > > ** > > ** > > > > ----- Original Message ----- > > *From:* AJ <[email protected]> > > *To:* [email protected] > > *Sent:* Wednesday, March 25, 2009 4:19 PM > > *Subject:* Re: [Repeater-Builder] Re: Sinclair Q2220E > > > > We have one in place right now on the 600 KHz split at 25 watts from a > > MastrII... > > Very noticeable desense... > > > > Not very happy with the setup... But we're doing the best we can with what > > was on the hill when we started... > > > > Oh well lol. > > > > On Tue, Mar 24, 2009 at 12:39 PM, ve7fet <[email protected]>wrote: > > > >> Actually, the comment below isn't quite true. > >> > >> The Q2220E is a "Res-Lok" duplexer, but there are no machined coupling > >> ports between the cavities. I just took the loops out of one to confirm. > >> > >> The coupling between the cavities is a function of the pickup loop inside > >> the cavity, and the coax between them. > >> > >> However, in the C2034 type Res-Lok combiners, there ARE coupling ports > >> machined between the bandpass section cavities (confirmed that too). > >> > >> Of interesting note on the Q2220E, the docs from Sincliar show two > >> different harnesses available, presumably one for high split, and one for > >> low. I have two Q2220E's here, one factory 143/148 and the other 152/157. > >> They both have the same harness on them (320mm inter-cavity of RG400), and > >> the pickup loops are the same size too (110mm). > >> > >> If you run the numbers for 320mm and a velocity factor of 0.695, you get a > >> center frequency for the harness of 163MHz. > >> > >> If you wanted to optimize the tuning for the best response in the ham > >> band, you may want to consider re-building the harness and changing the > >> inter-cavity lengths to 355mm. I wouldn't change the lengths of the pickup > >> loops as that is going to significantly change the response. > >> > >> Also note, the Q2220E makes a good candidate to modify for 220MHz... just > >> ask Dave Cameron... http://www.irlp.net/duplexer > >> > >> Cheers! > >> > >> Lee > >> > >> --- In [email protected]<Repeater-Builder%40yahoogroups.com>, > >> "Eric Lemmon" <wb6...@...> wrote: > >> > Part of the problem is that the Q2220E > >> > duplexer uses the "Res-Lok" design, wherein the coupling between > >> cavities of > >> > each pair is via a machined port between them, rather than a cabled > >> coupling > >> > loop that can be adjusted. > >> > >> > > > > >
