I have tuned many of these in the past, and the last set I tuned was doing exactly what you say. But they looked great on the HP 8920, but as soon as any power was run through them, the tuning went all to hell and there was major desense.
So I looked a little closer by taking the 80 odd screws off the top, and noticed that one of the tuning caps had some discoloration on it. I came to the conclusion that somebody tuned the unit under power and cooked one of the tuning caps. Once it was replaced, it tuned up and worked like a charm. Dave Cameron VE7LTD --- In [email protected], "Robert Pease" <[EMAIL PROTECTED]> wrote: > > Thanks Mike, > This was on our frequency before and working fine, we had a problem with > our repeater and when we brought it back we had really bad desense > problems, Our thought was that someone had "bumped" the duplexers and > knocked them off freq. I tried to check them there and they where way > off so I brought them home. > > I understand what duplexers do and how they work but these are > different, they are in one square unit. with the cables T'd to the > cavities, that tells me they are notch type. > I have had a few people tell me that I needed a new harness but it was > working on this freq with this harness fine. > > I'll take a look at the articles, maybe a lightbulb will go on in my > thick head! > > Rob > > > > ________________________________ > > From: [email protected] > [mailto:[EMAIL PROTECTED] On Behalf Of Mike Morris > WA6ILQ > Sent: Thursday, March 20, 2008 12:18 PM > To: [email protected] > Subject: Re: [Repeater-Builder] Sinclair Q2330E Duplexer question > > > > At 08:39 AM 03/20/08, you wrote: > > > I am the proud owner of a Sinclair Q2330E I am trying to tune it > using my newly aquired Motorola R2001D service monitor > Long story short the Duplexer is willing the battle and I want > to start over. > > Is there a default starting point for these, ie rods half way, > caps 4 turns down from the top. > > The unit is clearly factory marked with high pass, low pass, and > antenna, > > The problem is that some times it seems like the notch is on the > qrong side of the pass and I have to fight to move it to the correct > side. > and when I get one side low side tuned then tune the high side, > the low side gets messed up. > > I can tune each of the cavities independently with no problem, > but again when I put them all together they really get messed up. > > I have read most of the things on the site about tuning > duplexers and I think this is a notch type, maybe someone can confirm > that. > I tried the instructions from the Sinclair site and they seem to > simplistic and I never can seem to get both working. > > I thought I had it once and put when I put a dummy load on the > antenna port and looked from low to high pass with the spectrum analyzer > I expected to see two notches at both freqs, what I saw was not even > close. > > Another note, when I put a 1ft jumper between the out and the in > and look at the trace it looks almost flat. When I look at the jumpers > that where on the repeater I see a dip about 800kc below my low freq, > this moves 200-300kc with different length and type jumpers, Is this > normal? > If it was a wavelength vs cable length null thing I would think > it would move alot more than that. > > Also does anyone know on the 2001D how to set up to generate out > wht out port and monitor the signal at the in port for signal strength? > > I know I am probably missing something really obvious but I just > can't see it!! > > Sorry for all of the dumb questions at once but I am new to > duplexer tuning and am stumped. > > Thanks - Rob - KS4EC > > > This might help: > < http://www.repeater-builder.com/sinclair/q2330e-duplexer- tuning.pdf > <http://www.repeater-builder.com/sinclair/q2330e-duplexer- tuning.pdf> > > > But first spend an evening getting a basic education on duplexers (call > it "Duplexers 101") > > Yes, there is some repeated material between the seven articles, but > if you're new to duplexers, it won't hurt. When you have multiple > people > writing on the same topic some duplication is inevitable. > > < http://www.repeater-builder.com/antenna/ve2azx-duplexerinfo.pdf > <http://www.repeater-builder.com/antenna/ve2azx-duplexerinfo.pdf> > > < > http://www.repeater-builder.com/antenna/emr-corp-understanding- maintaini > ng-retuning-antenna-duplexers.pdf > <http://www.repeater-builder.com/antenna/emr-corp-understanding- maintain > ing-retuning-antenna-duplexers.pdf> > > < > http://www.repeater-builder.com/tx-rx/tx-rx-technical-notes-on- duplexer- > problems-and-remedies.pdf > <http://www.repeater-builder.com/tx-rx/tx-rx-technical-notes-on- duplexer > -problems-and-remedies.pdf> > > < > http://www.repeater-builder.com/tx-rx/tx-rx-combating-spurious- output-an > d-overloading-with-cavity-filters.pdf > <http://www.repeater-builder.com/tx-rx/tx-rx-combating-spurious- output-a > nd-overloading-with-cavity-filters.pdf> > > < http://www.repeater-builder.com/antenna/w6nbc-duplexer-index.html > <http://www.repeater-builder.com/antenna/w6nbc-duplexer- index.html> > > > The last one has some construction notes that can probably be skipped. > > Make sure your harness is the correct length. If your unit came from a > 150MHz or 160Mhz environment the inter-cavity jumpers may be too short. > If it's off by an inch or two I just add silver-plated (never nickel > plated) elbow > adapters to the ends as a test. If it tunes better then you know that > you > have a too-short harness. > > Note that duplexers are initially tuned and the ports labeled at the > factory. > A duplexer is built with a "higher" side and a "lower" side, and the > loops > and inter-cavity cabling are selected for those frequencies. The > application > a ham has may conflict with the original port labels. So look at the > original > label and note if the receive side is the higher of the two frequencies, > or if the > transmit side is... and keep the high/low relationship the same as you > retune > it. You may end up using the original receive side as your transmit > side. > > Mike WA6ILQ > > > > Since 1974, the award-winning Alpert JFCS has helped families of all faiths throughout most of Palm Beach County, FL, via counseling, seniors services, residences for the disabled, mentoring children, support groups and a lot more. > > SOLUTIONS FOR LIVING > www.JFCSonline.com > > Please take note of our new website and E-Mail Addresses. Please update your contacts ASAP. > > > > > -------------------------------------------------------------------- ------------ > > > NOTICE: > > This e-mail message and all attachments transmitted with it are intended solely for the use of the addressee and may contain legally privileged and confidential information. 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