I am fairly good at making documentation, and if this project works, I will create a PDF complete with pictures and dimensions to help others who may want to do this in the future.
I have learned: 1) I do not need to cut down the casing. The only reason to do this would be for sizing. 2) The connectors used on the ResLok duplexers are easily uncrimped and shortened, which means no additional expense for RG-142 cabling. 3) The loops may not need to be modified, as their orientation defines their resonance within the cavity. So turning them a bit may be all that is needed to get the proper loss/notch depth required for this 220 project. I have a nice camera, so I will document along the way. Dave Cameron VE7LTD --- In Repeater-Builder@yahoogroups.com, "Ron Wright, Skywarn Coodinator" <[EMAIL PROTECTED]> wrote: > > Mike, > > On the 220 cavity conversion this would be excellent posting on the > board info sheets. Might consider giving it to the board moderators > or posting in the FILES section. > > 73, ron, n9ee/r > > > --- In Repeater-Builder@yahoogroups.com, "Mike Mullarkey" <k7pfj@> > wrote: > > > > Hi David, > > > > > > > > I just finished modifying 6 900MHz 10" cavities to use at 440MHz > for a 3 > > channel receive combiner. Sinclair engineers will send you a PDF of > such > > cavity at 220 and the loop length. At first they will be hesitant > but they > > will eventually send it to you. For the loops just make new loops > and solder > > them to the connector. For the internal rod. Unsolder the tower and > leave > > the finger stock alone if possible to. > > > > > > > > Mike > > > > > > > > Oregon Repeater Linking Group > > > > Mike Mullarkey > > > > 6539 E Street > > > > Springfield, OR 97478 > > > > k7pfj@ > > > > www.orlg.org > > > > > > > > > > > > -----Original Message----- > > From: Repeater-Builder@yahoogroups.com > > [mailto:[EMAIL PROTECTED] On Behalf Of ve7ltd > > Sent: Saturday, January 06, 2007 11:22 PM > > To: Repeater-Builder@yahoogroups.com > > Subject: [Repeater-Builder] Modification of Sinclair Q2220E 144Mhz > duplexer > > to 220Mhz > > > > > > > > I have recently aquired a functional high-split (148-174) Sinclair > > Q2220E. Since it does not have enough isolation for my 100W VHF > > repeater, and I already have a good working Q202 on there now, I am > > planning to convert this over to a Q2221E for 220Mhz. > > > > I am pretty aware of how duplexers work and the coupling harness > and > > 1/4 wave characteristics, so my questions are very specific. I have > a > > Q3330C (compact UHF 6 cavity) and the Q202 that I have looked at > for > > comparing loops and such. I have already determined how I have to > > reduce the length of the interconnecting harness with the velocity > > factor and such. > > > > The only questions I have are: > > 1) The coupling loop (with the connector and the variable > capactior) > > on the Q2220E is obviously sized for 148-174. How should the > > dimensions be changed to work to 220? The reason I am confused is > the > > UHF is the same length, but not as spread open. and made from wider > > copper stock. The Q202 is much more spread open and larger. What is > > the electrical/RF characteristics of this loop supposed to be? > > > > 2) I know I have to cut down the hollow rod support and the finger > > stock on the internals of the duplexer to accomodate the 1/4 wave > > resonance inside for 220. No problem. But, does the depth of the > > cavity matter? Do I have to shorten the casing as well? I know in > the > > past when I removed the bottom of the large Q202 cans, the bottom > > being in place or not had little effect on the tuning. If I left > the > > casing alone, would I still be able to tune it to 220? > > > > Thanks for your insight. > > > > Dave Cameron > > VE7LTD > > >
