Re: [Repeater-Builder] Narrowbanding
Here in Washington State our agency is running on 7.5 channels using 11K2F3D/11K2F3E. Frequency coordination has to be a little creative as the channels of course overlap. Need to keep the repeaters far enough apart such the signal level of the overlap is of no consequence to the adjacent channel. This is much the same concept used in CA years ago when two meters was switched 15 kHz channel centers. Rob K7TGU - Original Message - From: MCH m...@nb.net To: Repeater-Builder@yahoogroups.com Sent: Monday, August 02, 2010 13:16 Subject: Re: [Repeater-Builder] Narrowbanding I was wondering about that myself. A couple of comments on the other aspects: 1. I see this as falling flat on its face. May as well mandate D-STAR. 2. How are the commercial people fitting SNFM in 7.5 kHz channels as they have been doing on VHF? Joe M. Chuck Kelsey wrote: How wide is it? Chuck WB2EDV - Original Message - From: wd8chl wd8...@gmail.com To: Repeater-Builder@yahoogroups.com Sent: Monday, August 02, 2010 10:58 AM Subject: Re: [Repeater-Builder] Narrowbanding ...or that think the US DTV standard fits in a 6 MHz channel...NOT! Yahoo! Groups Links Yahoo! Groups Links
Re: [Repeater-Builder] VHF Vari-Notch Duplexers - 2 x 2 x 4 ???
The duplexer that you have may not be a Vari-Notch unit. Your description sounds like a 30 series unit (Model number will start with a 30 e.g. 30-36-01A) The 30 series VHF duplexers are specially designed to work with repeaters that exhibit problems when connected to high selectivity duplexers. This design uses three standard notch type filters on the transmitter side which provide excellent noise filtering while maintaining a relatively low VSWR over a wide frequency range. This helps minimize transmitter sensitivity to cable length between the duplexer and the transmitter and also reduces the potential for transmitter spurs. The receiver portion of the duplexer incorporates three pseudo bandpass filters to give isolation to the transmit carrier and reduce interference and intermodulation caused by other nearby transmitters. Because different types of cavity filters are used for the transmit and receive sides of the duplexer, it is important that the correct model be used. Model numbers are different for units designed for either the transmitter higher or lower than the receiver frequency. I have tuning instructions if this sounds like the unit. Rob K7TGU - Original Message - From: tahrens301 tahr...@swtexas.net To: Repeater-Builder@yahoogroups.com Sent: Thursday, January 28, 2010 15:37 Subject: [Repeater-Builder] VHF Vari-Notch Duplexers - 2 x 2 x 4 ??? Well, I thought this thing was tuned up, but obviously something is wrong. These are a set of the 2x2x4 cavities... have a plunger in the front, and a variable cap adjustment on the back. Also, a pair of BNC connectors on the capacitor side. The plate says Duplexer Vari-Notch, 147-174 It also implies that the TX has a 1.5dB insertion loss, but darned if I can get only about 4.5. I've talked to the guys at TX/RX, and they are looking for a book on them, but nothing yet. Anybody have any tuning instructions/info on them? The plunger is marked 'pass low', and the cap is reject high. Pretty much self explanatory, and they tune ok, but the insertion loss is higher than it appears it should be. Thanks, Tim Yahoo! Groups Links
Re: [Repeater-Builder] Re: VHF Vari-Notch Duplexers - 2 x 2 x 4 ???
The 28-41-05 is indeed a Vari-Notch unit. We have a hundred or so 28-37-06C units in service. The manual for the 28-37-06C covers 17 different models, however, the 28-41-05 is not among those. Sorry I couldn't help out. Regards, Rob K7TGU - Original Message - From: tahrens301 tahr...@swtexas.net To: Repeater-Builder@yahoogroups.com Sent: Thursday, January 28, 2010 17:28 Subject: [Repeater-Builder] Re: VHF Vari-Notch Duplexers - 2 x 2 x 4 ??? Hi Rob, Sorry, I forgot to put the model number in the original posting! It's 28-41-05 It has 3 of the blocks in the TX line, and 2 in the RX. It's in a 2 1/4 thick rack panel. I opened one up, and it looks like a helical resonator with a silver slug that goes in and out, and the BNC connectors have a loop that is 90 degrees to the larger coil and has an air variable cap to ground. thanks! Tim --- In Repeater-Builder@yahoogroups.com, Rob Lee r...@... wrote: The duplexer that you have may not be a Vari-Notch unit. Your description sounds like a 30 series unit (Model number will start with a 30 e.g. 30-36-01A) The 30 series VHF duplexers are specially designed to work with repeaters that exhibit problems when connected to high selectivity duplexers. This design uses three standard notch type filters on the transmitter side which provide excellent noise filtering while maintaining a relatively low VSWR over a wide frequency range. This helps minimize transmitter sensitivity to cable length between the duplexer and the transmitter and also reduces the potential for transmitter spurs. The receiver portion of the duplexer incorporates three pseudo bandpass filters to give isolation to the transmit carrier and reduce interference and intermodulation caused by other nearby transmitters. Because different types of cavity filters are used for the transmit and receive sides of the duplexer, it is important that the correct model be used. Model numbers are different for units designed for either the transmitter higher or lower than the receiver frequency. I have tuning instructions if this sounds like the unit. Rob K7TGU - Original Message - From: tahrens301 tahr...@... To: Repeater-Builder@yahoogroups.com Sent: Thursday, January 28, 2010 15:37 Subject: [Repeater-Builder] VHF Vari-Notch Duplexers - 2 x 2 x 4 ??? Well, I thought this thing was tuned up, but obviously something is wrong. These are a set of the 2x2x4 cavities... have a plunger in the front, and a variable cap adjustment on the back. Also, a pair of BNC connectors on the capacitor side. The plate says Duplexer Vari-Notch, 147-174 It also implies that the TX has a 1.5dB insertion loss, but darned if I can get only about 4.5. I've talked to the guys at TX/RX, and they are looking for a book on them, but nothing yet. Anybody have any tuning instructions/info on them? The plunger is marked 'pass low', and the cap is reject high. Pretty much self explanatory, and they tune ok, but the insertion loss is higher than it appears it should be. Thanks, Tim Yahoo! Groups Links Yahoo! Groups Links
RE: [Repeater-Builder] VHF spectras
My apologies ... This was not intended for the list ... Rob -Original Message- From: Rob Lee [mailto:[EMAIL PROTECTED] Sent: Saturday, June 05, 2004 11:07 AM To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] VHF spectras Hi Doug, Just curious about the particulars regarding the Spectras i.e. power out, type of control head, price, etc. Thanks, Rob K7TGU -Original Message- From: doug [mailto:[EMAIL PROTECTED] Sent: Saturday, June 05, 2004 8:56 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] VHF spectras if anyone on the list is interested in purchasing some Motorola Spectra VHF remote mount radios (146-174) please message me OFF THE LIST. and a note for kevin --- isn't there still a paypal account for rbtip?? if there is, lemme know so i can kick a donation to u doug kc5bmj Yahoo! Groups Links --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.693 / Virus Database: 454 - Release Date: 5/31/2004 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.693 / Virus Database: 454 - Release Date: 5/31/2004 Yahoo! Groups Links --- Incoming mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.693 / Virus Database: 454 - Release Date: 5/31/2004 --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.693 / Virus Database: 454 - Release Date: 5/31/2004 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/
