Re: [Repeater-Builder] Wacom 678-A
Always terminate the un-used port in a 50 ohm load. A 20 dB pad will work here as the return loss is 40 dB. Neil - WA6KLA Ken Arck wrote: At 05:18 PM 6/15/2005 -0700, you wrote: It sometimes helps to use 6 dB attenuators on either side of the cavity when tuning in this manner, so that a relatively uniform impedance is presented. ---I would argue that you should ALWAYS use a pad (3 or 6 dB) when tuning a cavity. If for no other reason, to present an accurate 50 ohm load. I never tune a duplexer (or cavities) without a pad on each port. Ken Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Wacom 678-A
At 02:21 PM 6/21/2005, Neil McKie wrote: Always terminate the un-used port in a 50 ohm load. A 20 dB pad will work here as the return loss is 40 dB. Termination is easy, and inexpensive. I've just begun to build my library of attenuators. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Wacom 678-A
At 12:21 PM 6/21/2005 -0700, you wrote: Always terminate the un-used port in a 50 ohm load. ---Of course but I'm a firm believe in using a pad on every port. It's the only way to guarantee a 50 ohm load on them. Ken -- President and CTO - Arcom Communications Makers of state-of-the-art repeater controllers and accessories. http://www.ah6le.net/arcom/index.html We offer complete Kenwood TKR repeater packages! AH6LE/R - IRLP Node 3000 http://www.irlp.net Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Wacom 678-A
At 6/21/2005 12:46 PM, you wrote: At 12:21 PM 6/21/2005 -0700, you wrote: Always terminate the un-used port in a 50 ohm load. ---Of course but I'm a firm believe in using a pad on every port. It's the only way to guarantee a 50 ohm load on them. Ken How very true. I once tried to tune a (passive) filter using a sig. gen. Yaesu FT-8500; measured 1 dB of GAIN on the filter! A 10 dB pad on the 8500 fixed that measurement error. Bob NO6B Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Wacom 678-A
At 03:12 PM 6/21/2005, Bob Dengler wrote: At 6/21/2005 12:46 PM, you wrote: At 12:21 PM 6/21/2005 -0700, you wrote: Always terminate the un-used port in a 50 ohm load. ---Of course but I'm a firm believe in using a pad on every port. It's the only way to guarantee a 50 ohm load on them. Ken How very true. I once tried to tune a (passive) filter using a sig. gen. Yaesu FT-8500; measured 1 dB of GAIN on the filter! A 10 dB pad on the 8500 fixed that measurement error. That's no filter, that's an oscillator! :) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Wacom 678-A
Dave, Here's the WP-678 tuning instructions: http://www.repeater-builder.com/wacom/wp678-665-UHF-tuninginstructions.pdf 73, Eric Lemmon WB6FLY Dave VanHorn wrote: Does anyone have tuning instructions for these? The pass is easy, and it's done, but I don't see how to adjust the notch frequency. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Wacom 678-A
At 01:05 AM 6/15/2005, Eric Lemmon wrote: Dave, Here's the WP-678 tuning instructions: http://www.repeater-builder.com/wacom/wp678-665-UHF-tuninginstructions.pdf AH! It's under the covers! I didn't know if those were screws or covers, or what. Thanks, all done now, it only takes a few minutes, and is not very hard at all. I re-ran the tuning a second time, and almost exactly where I was the first time, so I guess I got it right. The notches are deep enough that my SA can't see the signal at the bottom. :) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Wacom 678-A
Dave, Congratulations! It's always good to hear about successes in duplexer tuning. (The dust covers on those Johansen tuning capacitors have fooled a LOT of people!) One little tip: If you want to squeeze the utmost performance from your duplexer, but your spectrum analyzer doesn't have the dynamic range to display the full extent of the notch, then try tuning each can individually. It sometimes helps to use 6 dB attenuators on either side of the cavity when tuning in this manner, so that a relatively uniform impedance is presented. If the jumper cables are the correct length, the combined performance of the cavities *should* be the sum of the individual cavities, minus the losses in the jumpers. When you are pushing the envelope of the cavity tuning art, it is a good thing to ensure that your spectrum analyzer or network analyzer is exactly on frequency. One trick is to use a known-accurate service monitor to generate a birdie that can be loosely coupled into the less-accurate spectrum analyzer to display a calibration mark on its display. 73, Eric Lemmon WB6FLY Dave VanHorn wrote: AH! It's under the covers! I didn't know if those were screws or covers, or what. Thanks, all done now, it only takes a few minutes, and is not very hard at all. I re-ran the tuning a second time, and almost exactly where I was the first time, so I guess I got it right. The notches are deep enough that my SA can't see the signal at the bottom. :) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Wacom 678-A
At 05:18 PM 6/15/2005 -0700, you wrote: It sometimes helps to use 6 dB attenuators on either side of the cavity when tuning in this manner, so that a relatively uniform impedance is presented. ---I would argue that you should ALWAYS use a pad (3 or 6 dB) when tuning a cavity. If for no other reason, to present an accurate 50 ohm load. I never tune a duplexer (or cavities) without a pad on each port. Ken Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Wacom 678-A
If the jumper cables are the correct length, the combined performance of the cavities *should* be the sum of the individual cavities, minus the losses in the jumpers. That is a question, it was on 460-ish, now 440-ish. Seems like still a relatively small change, but I don't know EXACTLY how to measure the cables to make the new ones the right length, so it seems likely that changing them would just make it worse. When you are pushing the envelope of the cavity tuning art, it is a good thing to ensure that your spectrum analyzer or network analyzer is exactly on frequency. One trick is to use a known-accurate service monitor to generate a birdie that can be loosely coupled into the less-accurate spectrum analyzer to display a calibration mark on its display. Yup, that's what I use. Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
