Re: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters
I moved a couple of 400 mHz cavities up into the 450 band by removing a couple of large washers that were welded to the end of the center rod. If your cavities do not have a large washer on the end, or have one that can be increased in diameter by soldering a larger washer to the existing one, you might get yours down into the ham band by adding a larger washer. The washers in my cavities were silver plated along with the center rod, so that might be a problem for you, but worth a try - 73 - Jim W5ZIT --- On Sat, 8/16/08, Joe Burkleo <[EMAIL PROTECTED]> wrote: From: Joe Burkleo <[EMAIL PROTECTED]> Subject: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters To: Repeater-Builder@yahoogroups.com Date: Saturday, August 16, 2008, 9:33 PM Has anyone ever converted a 66-88 MHz Tx-Rx BpBr cavity for us on 6 Meters? I came across 2 of these and I could get them down to 57 MHz but that was about it. Thanks, Joe - WA7JAW _,___
Re: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters
This is going the wrong direction. His cans will be too short. Chuck WB2EDV - Original Message - From: Jim Brown To: Repeater-Builder@yahoogroups.com Sent: Saturday, August 16, 2008 11:35 PM Subject: Re: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters I moved a couple of 400 mHz cavities up into the 450 band by removing a couple of large washers that were welded to the end of the center rod. If your cavities do not have a large washer on the end, or have one that can be increased in diameter by soldering a larger washer to the existing one, you might get yours down into the ham band by adding a larger washer. The washers in my cavities were silver plated along with the center rod, so that might be a problem for you, but worth a try - 73 - Jim W5ZIT --- On Sat, 8/16/08, Joe Burkleo <[EMAIL PROTECTED]> wrote: From: Joe Burkleo <[EMAIL PROTECTED]> Subject: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters To: Repeater-Builder@yahoogroups.com Date: Saturday, August 16, 2008, 9:33 PM Has anyone ever converted a 66-88 MHz Tx-Rx BpBr cavity for us on 6 Meters? I came across 2 of these and I could get them down to 57 MHz but that was about it. Thanks, Joe - WA7JAW _,___
RE: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters
I had a few Sinclair LB cans (from a LB hybrid ring duplexor) some years ago that were in the 30-40MHz range. They had a "can" about 12in long by about 3 inches in diameter silver soldered to the moveable end of the resonator. Removing these with an acetylene torch raised the frequency by about 10MHz (ie 35MHz went to 45MHz) in the center of its tuning range. Adding such a "can" or tophat capacitor to your cans should lower their frequency by the same percentage. I also had a high band VHF can that tuned the aircraft band that had a similar can on it except that it was only 2in long. More like a cup. Removing that raised the range to 132 -150 or more. The diameter of the added "can" appeared to be about 2-1/2 to 3 times the diameter of the resonator. The length would be whatever was required to achieve the end result. Any of these tophat capacitors will lower the Q of the can but at 6m you have lots of spare leeway with 1 mHz separation. Burt VE2BMQ >Has anyone ever converted a 66-88 MHz Tx-Rx BpBr cavity for us on 6 >Meters? I came across 2 of these and I could get them down to 57 MHz >but that was about it. > >Thanks, >Joe - WA7JAW > >
Re: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters
Read it again Chuck - 73 - Jim W5ZIT --- On Sun, 8/17/08, Chuck Kelsey <[EMAIL PROTECTED]> wrote: From: Chuck Kelsey <[EMAIL PROTECTED]> Subject: Re: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters To: Repeater-Builder@yahoogroups.com Date: Sunday, August 17, 2008, 8:54 AM This is going the wrong direction. His cans will be too short. Chuck WB2EDV - Original Message - From: Jim Brown To: Repeater-Builder@ yahoogroups. com Sent: Saturday, August 16, 2008 11:35 PM Subject: Re: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters I moved a couple of 400 mHz cavities up into the 450 band by removing a couple of large washers that were welded to the end of the center rod. If your cavities do not have a large washer on the end, or have one that can be increased in diameter by soldering a larger washer to the existing one, you might get yours down into the ham band by adding a larger washer. The washers in my cavities were silver plated along with the center rod, so that might be a problem for you, but worth a try - 73 - Jim W5ZIT --- On Sat, 8/16/08, Joe Burkleo <[EMAIL PROTECTED] com> wrote: From: Joe Burkleo <[EMAIL PROTECTED] com> Subject: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters To: Repeater-Builder@ yahoogroups. com Date: Saturday, August 16, 2008, 9:33 PM Has anyone ever converted a 66-88 MHz Tx-Rx BpBr cavity for us on 6 Meters? I came across 2 of these and I could get them down to 57 MHz but that was about it. Thanks, Joe - WA7JAW _,___ ___._,___
Re: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters
- Original Message - From: <[EMAIL PROTECTED]> To: Sent: Sunday, August 17, 2008 11:56 AM Subject: RE: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters >I had a few Sinclair LB cans (from a LB hybrid ring duplexor) some years >ago that were in the 30-40MHz range. They had a "can" about 12in long by >about 3 inches in diameter silver soldered to the moveable end of the >resonator. Removing these with an acetylene torch raised the frequency by >about 10MHz (ie 35MHz went to 45MHz) in the center of its tuning range. > > Adding such a "can" or tophat capacitor to your cans should lower their > frequency by the same percentage. I also had a high band VHF can that > tuned the aircraft band that had a similar can on it except that it was > only 2in long. More like a cup. Removing that raised the range to > 132 -150 or more. > > The diameter of the added "can" appeared to be about 2-1/2 to 3 times the > diameter of the resonator. The length would be whatever was required to > achieve the end result. > > Any of these tophat capacitors will lower the Q of the can but at 6m you > have lots of spare leeway with 1 mHz separation. > > Burt VE2BMQ > > >>Has anyone ever converted a 66-88 MHz Tx-Rx BpBr cavity for us on 6 >>Meters? I came across 2 of these and I could get them down to 57 MHz >>but that was about it. >> >>Thanks, >>Joe - WA7JAW >> >> > > > > > > Yahoo! Groups Links > > >
Re: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters
You learn something new every day. I've never heard of doing this. By the way, Burt, did you get my direct email yesterday? Chuck WB2EDV - Original Message - From: <[EMAIL PROTECTED]> To: Sent: Sunday, August 17, 2008 11:56 AM Subject: RE: [Repeater-Builder] TX-RX 66-88 MHz Cavity to 6 Meters >I had a few Sinclair LB cans (from a LB hybrid ring duplexor) some years >ago that were in the 30-40MHz range. They had a "can" about 12in long by >about 3 inches in diameter silver soldered to the moveable end of the >resonator. Removing these with an acetylene torch raised the frequency by >about 10MHz (ie 35MHz went to 45MHz) in the center of its tuning range. > > SNIP
