Re: [Repeater-Builder] VHF Duplexer needed
Not db4001 but instead, db4002...same url. ssb - Original Message - From: "Steve S. Bosshard (NU5D)" <[EMAIL PROTECTED]> To: Sent: Monday, November 03, 2003 11:58 PM Subject: Re: [Repeater-Builder] VHF Duplexer needed | Sounds like some DB4001's | | visit http://www.decibelproducts.com/smlist.asp?smy=5&smx=1 | | ssb | --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.535 / Virus Database: 330 - Release Date: 11/2/2003 Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] VHF Duplexer needed
Sounds like some DB4001's visit http://www.decibelproducts.com/smlist.asp?smy=5&smx=1 ssb - Original Message - From: "NØATH" <[EMAIL PROTECTED]> To: Sent: Monday, November 03, 2003 11:32 PM Subject: Re: [Repeater-Builder] VHF Duplexer needed | If permitted here ? I have a couple of GE VHF duplexers that are pass only. | These things are large and heavy - Solid copper throughout - 3" slugs - 12" | cans | N-connectors - 3/8 x 24 tuning rods - 70 miles SE of Kansas City Mo. | | NØATH at ARRL dot net | Dave | --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.535 / Virus Database: 330 - Release Date: 11/1/2003 Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] VHF Duplexer needed
If permitted here ? I have a couple of GE VHF duplexers that are pass only. These things are large and heavy - Solid copper throughout - 3" slugs - 12" cans N-connectors - 3/8 x 24 tuning rods - 70 miles SE of Kansas City Mo. NØATH at ARRL dot net Dave Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] VHF Duplexer needed
Figuring 60 ft of coax and a ringo or better, have you thought about split site? Receiver one location, Transmitter another with a 438 MHZ link between them? :Might fit the bill in the interim. ssb - Original Message - From: "Dave Schmidt" <[EMAIL PROTECTED]> To: Sent: Monday, November 03, 2003 9:37 PM Subject: Re: [Repeater-Builder] VHF Duplexer needed | Thanks for the great info Eric! I obviously cannot afford new so in | --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.535 / Virus Database: 330 - Release Date: 11/1/2003 Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] VHF Duplexer needed
Thanks for the great info Eric! I obviously cannot afford new so in order to weed out the stuff that cannot be used that is often found on E-Bay I thought I post the question here to find out what I should be looking for. When I mentioned cheap, I was thinking in the range of $250-300 or so... not a $1500 TXRX set ;-) On top of which, this is by far, not for building a wide coverage repeater. I only have a 60ft tower; this is more or less for me to learn with. How to build effetive systems for a knowlege base so when I do wind up with some commercial tower space, I have the knowlege to do it right quickly the first time. I have a decent UHF system using low cost stuff that required me to work at it to get it so it has decent coverage with the surounding terrain around me. VHF would help fill in the spots where the UHF does not make it - hence my want to build up a VHF machine. If it requires me to work on something to get it to work right, heck, that's what ham radio is in my eyes not some order it from the internet catalog then plug and play. By building it, working it into a working system, if something goes wrong, I can very quickly identify the problem and fix it. Thats the way I look at it. Again, thanks for the info and for keeping it within the subject I started ... not varing off explaining about using seperate antennas or saying I should go into another aspect of the hobby if I cannot afford top of the line stuff. Dave Schmidt / N9NLU --- Eric Lemmon <[EMAIL PROTECTED]> wrote: > Dave, > > It is important to understand that ANY duplexer that will handle a > 600 > kHz split at 2m is neither cheap nor abundant. The only 2m duplexers > that I usually see on the hamfest market are those that just don't > make > the grade in a good system. You won't normally see really good 2m > duplexers being sold for any price on the used market for one simple > reason: The owners know they have a good duplexer, and they keep it > in > service! > > Okay, here's some guidelines. If you have a crystal-controlled > repeater > that puts out 50 watts or so from a tube PA in the transmitter, and > the > receiver has a string of helical resonators in the front end, you > MIGHT > get by with a four-cavity duplexer of the bandpass/notch variety. > However, if you have a synthesized transmitter, you now have to deal > with a lot of "synthesizer noise" that is not present in a > single-frequency transmitter. Your synthesized transmitter probably > has > a broadband solid-state PA that amplifies the broadband synthesizer > noise along with the fundamental carrier. Not only is such a "low-Q" > amp noisy, but its untuned output circuit has an impedance that > varies > with power level- not conducive to a good match to the duplexer. > Finally, your synthesized receiver probably has a very broadband > front > end, a virtual "barn door" for all the PA noise and adjacent channel > noise to enter and cause major desensing. > > Not all duplexers are created equal. I have had several WACOM, > TX-RX, > Sinclair, and EMR duplexers pass through my hands in the past few > months, and I have learned some interesting things. First of all, > size > does not indicate just the power rating. A larger cavity has a > higher > "Q" meaning that it can be tuned more sharply and with a greater > notch > depth. They are also more costly. In many cases, a pass/notch > duplexer > with six, four-inch cavities will outperform most duplexers having > four, > seven- or eight-inch cavities. But, the bandpass tuning of such > duplexers is often rather vague. An ideal pass/notch duplexer SHOULD > have a deep sharp notch for the reject side AND a narrow sharp peak > for > the pass side. Reality check: Most pass/notch duplexers do well on > the > notch task, but fail miserably on the pass task- they have a small > "hump" at the pass frequency, but there is practically no useful > selectivity. If you have a noisy PA with lots of synthesizer spurs, > you > must filter out all of that chaff and keep just the wheat. You guys > with the GE tube PAs are gloating, because such tuned PAs are > legendary > in their freedom from noise. > > The solution is to follow your pass/notch duplexer with at least two > bandpass-only cavities at the RX input. This will filter out your > PA's > noise, and will also protect your RX front end. I am quite certain > that > many other repeater builders will agree that it's possible to have a > good repeater when the duplexer, antenna, and feedline are the best > you > can afford, when mated with a cheap transceiver. The converse, > however, > is not true. Please don't spend all your dough on the transceiver, > and > then skimp on the rest. > > 73, Eric Lemmon WB6FLY > > cworksmidwest wrote: > > > > I'm building a VHF high band repeater... on a tight budget. I have > > everything except a duplexer. I need some recomendations on cheap > > abundant duplexers that will do the 600Khz split. Max power I'
Re: [Repeater-Builder] FS: 900Mhz Repeater system, amplifier, Mobile radio
In a message dated 10/29/03 10:43:50 PM Eastern Standard Time, [EMAIL PROTECTED] writes: Bay Dave, Sent you a couple of emails on the GTX mobile. Is it still available? Fred Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
Re: [Repeater-Builder] VHF Duplexer needed
Dave, It is important to understand that ANY duplexer that will handle a 600 kHz split at 2m is neither cheap nor abundant. The only 2m duplexers that I usually see on the hamfest market are those that just don't make the grade in a good system. You won't normally see really good 2m duplexers being sold for any price on the used market for one simple reason: The owners know they have a good duplexer, and they keep it in service! Okay, here's some guidelines. If you have a crystal-controlled repeater that puts out 50 watts or so from a tube PA in the transmitter, and the receiver has a string of helical resonators in the front end, you MIGHT get by with a four-cavity duplexer of the bandpass/notch variety. However, if you have a synthesized transmitter, you now have to deal with a lot of "synthesizer noise" that is not present in a single-frequency transmitter. Your synthesized transmitter probably has a broadband solid-state PA that amplifies the broadband synthesizer noise along with the fundamental carrier. Not only is such a "low-Q" amp noisy, but its untuned output circuit has an impedance that varies with power level- not conducive to a good match to the duplexer. Finally, your synthesized receiver probably has a very broadband front end, a virtual "barn door" for all the PA noise and adjacent channel noise to enter and cause major desensing. Not all duplexers are created equal. I have had several WACOM, TX-RX, Sinclair, and EMR duplexers pass through my hands in the past few months, and I have learned some interesting things. First of all, size does not indicate just the power rating. A larger cavity has a higher "Q" meaning that it can be tuned more sharply and with a greater notch depth. They are also more costly. In many cases, a pass/notch duplexer with six, four-inch cavities will outperform most duplexers having four, seven- or eight-inch cavities. But, the bandpass tuning of such duplexers is often rather vague. An ideal pass/notch duplexer SHOULD have a deep sharp notch for the reject side AND a narrow sharp peak for the pass side. Reality check: Most pass/notch duplexers do well on the notch task, but fail miserably on the pass task- they have a small "hump" at the pass frequency, but there is practically no useful selectivity. If you have a noisy PA with lots of synthesizer spurs, you must filter out all of that chaff and keep just the wheat. You guys with the GE tube PAs are gloating, because such tuned PAs are legendary in their freedom from noise. The solution is to follow your pass/notch duplexer with at least two bandpass-only cavities at the RX input. This will filter out your PA's noise, and will also protect your RX front end. I am quite certain that many other repeater builders will agree that it's possible to have a good repeater when the duplexer, antenna, and feedline are the best you can afford, when mated with a cheap transceiver. The converse, however, is not true. Please don't spend all your dough on the transceiver, and then skimp on the rest. 73, Eric Lemmon WB6FLY cworksmidwest wrote: > > I'm building a VHF high band repeater... on a tight budget. I have > everything except a duplexer. I need some recomendations on cheap > abundant duplexers that will do the 600Khz split. Max power I'll be > using is 50 - 75W so recomendations for some Monster wacom or TXRX > duplexers that can handle a bazilion watts do not need to be posted, > besides, I probably wouldn't be able to afford ANY used wacom or txrx > duplexer sets. > > If you have something low cost that can work or if you know of > something cheap that can work, let me know. > > Thanks > > Dave / N9NLU > > > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Anyone using LDG RVS-8 Voter?
I am happy with my LDG unit. It may take several trips to your site to get it adjusted they way you want. Mine hasn't given any trouble except sometimes the LCD display says I have an active COS when I don't. It doesn't affect the operation. Dave/kx4i __ Reply Separator _ Subject: [Repeater-Builder] Anyone using LDG RVS-8 Voter? Author: at Internet_mail Date:11/2/2003 1:04 AM We are planning our first voted receiver and are trying to choose between the Doug Hall and the LDG voters. I have a local repeater using the Doug Hall, so I was looking for some feedback on the LDG. Thanks for any opinions and advice. Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
[Repeater-Builder] Re: Tuning of DB4613-1A Circulator
Hi Jeff, > "Jeff DePolo WN3A" <[EMAIL PROTECTED]> wrote: > Even pass cavities don't necessarily attenuate harmonics > produced by a circulator sufficiently. This is true, it's all a game of numbers and good test equipment. > A 1/4 wave cavity will have a very good pass response at 3/4 > wave (3rd harmonic). Even at other harmonics, or between > harmonics, a bandpass cavity isn't necessarily going to give you > adequate attenuation of the harmonics. The large fly in the soup is the 2nd Harmonic. People should also be aware of UHF Cavities which are 3/4 wave, much betta' For single unit operation, one of the better layouts is the circulator followed by at least a 5 pole low pass filter, the output sent to a band pass, band reject duplexer. > A pass can is always good practice on any transmitter, but a > one-stop-shopping cure for isolator harmonics it is not. There is no cure, only practical harmonic reduction techniques. > And be careful of the varieties of "harmonic filters" out there. > Some of the cheaper ones are just 2nd harmonic traps. They'll > knock down the 2nd harmonic by 40 dB or so, but do nothing for the > 3rd and higher harmonics, which can really be a problem on highband > (3rd harmonic ends up on UHF). A real low-pass filter is what > you should use. > Jeff Low pass filters are most often supplied/recomended with circulators. They are actually simple to make, most often commercially priced +13dB or higher than the actual parts used to make them. The real story is told with good test equipment. cheers Skipp skipp025 @yahoo.com Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
RE: [Repeater-Builder] Re: Tuning of DB4613-1A Circulator
Even pass cavities don't necessarily attenuate harmonics produced by a circulator sufficiently. A 1/4 wave cavity will have a very good pass response at 3/4 wave (3rd harmonic). Even at other harmonics, or between harmonics, a bandpass cavity isn't necessarily going to give you adequate attenuation of the harmonics. A pass can is always good practice on any transmitter, but a one-stop-shopping cure for isolator harmonics it is not. And be careful of the varieties of "harmonic filters" out there. Some of the cheaper ones are just 2nd harmonic traps. They'll knock down the 2nd harmonic by 40 dB or so, but do nothing for the 3rd and higher harmonics, which can really be a problem on highband (3rd harmonic ends up on UHF). A real low-pass filter is what you should use. --- Jeff - Jeff DePolo WN3A Broadcast and Communications Consultant > -Original Message- > From: skipp025 [mailto:[EMAIL PROTECTED] > Sent: Monday, November 03, 2003 1:38 PM > To: Repeater-Builder@yahoogroups.com > Subject: [Repeater-Builder] Re: Tuning of DB4613-1A Circulator > > > Hi Jim, > > As Eric mentioned in a reply post, Decibel has much > information on line. > > One thing to know is that circulator tuning adjustments are > slightly different for large vs small power levels. It's > probably ok to do an initial "ballpark" tune using lower > power, but the actual final tune should be done at the system > normal/full power level. > > Circulators should also be followed by some form of harmonic > filtering. In many cases, a band pass duplexer cavity or low > pass filter are used. > > A circulator followed by a notch-notch or notch-pass duplexer > is not a very good practice. In some applications, the > results might be worse than running without a circulator. > > cheers > skipp > > > > > "Jim Cicirello" <[EMAIL PROTECTED]> wrote: > > Can anyone help me with the tuning instructions for the Decibel > > Circulator listed above. It has an adjustment on the input, output > > and one towards the attached dummy load. I can tune it, but I am > > loosing 3 DB of power. On of the few articles I can find > shows a loss > > of 0.4dB. Any help appreciated. > > > > 73 JIm KA2AJH > > > > > > > Your use of Yahoo! Groups is subject to > http://docs.yahoo.com/info/terms/ > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
[Repeater-Builder] Re: Tuning of DB4613-1A Circulator
Hi Jim, As Eric mentioned in a reply post, Decibel has much information on line. One thing to know is that circulator tuning adjustments are slightly different for large vs small power levels. It's probably ok to do an initial "ballpark" tune using lower power, but the actual final tune should be done at the system normal/full power level. Circulators should also be followed by some form of harmonic filtering. In many cases, a band pass duplexer cavity or low pass filter are used. A circulator followed by a notch-notch or notch-pass duplexer is not a very good practice. In some applications, the results might be worse than running without a circulator. cheers skipp > "Jim Cicirello" <[EMAIL PROTECTED]> wrote: > Can anyone help me with the tuning instructions for the Decibel > Circulator listed above. It has an adjustment on the input, output > and one towards the attached dummy load. I can tune it, but I am > loosing 3 DB of power. On of the few articles I can find shows a loss > of 0.4dB. Any help appreciated. > > 73 JIm KA2AJH Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: VHF Duplexer needed
> Spend your money on a good duplexer and good antenna. The other stuff is the > cheap stuff. The antenna and duplexer are the two most important components > of a repeater system by far. Don't forget to use double shielded feedline everywhere. I know there is some controversy on LMR-400 vs. Heliax (I use LMR-400 for my "toy" at home) but RG-58, RG-8, RG-213 are definitely out. Don't forget to use quality double shielded coax for all your test lead, too. Adi -- Adi Linden | va3adi | [EMAIL PROTECTED] | http://adis.ca +-+ IRLP Node 2590 in Sioux Lookout, Ontario Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: VHF Duplexer needed
Kind of like good speakers and an amp on a tuner ssb - Original Message - From: "Chuck Kelsey" <[EMAIL PROTECTED]> To: Sent: Monday, November 03, 2003 5:45 AM Subject: Re: [Repeater-Builder] Re: VHF Duplexer needed | I agree with Kevin. | | All too often one hears someone say they have everything they need to make a | repeater, except for a duplexer. They expect to use a piece of crap antenna, | too. | | Spend your money on a good duplexer and good antenna. The other stuff is the | cheap stuff. The antenna and duplexer are the two most important components | of a repeater system by far. | | Chuck | WB2EDV | | | > ><[EMAIL PROTECTED]> wrote: | > > | > > | > >>I'm building a VHF high band repeater... on a tight budget. I have | everything except a duplexer. I need some recomendations on cheap abundant | duplexers that will do the 600Khz split. Max power I'll be using is 50 - 75W | so recomendations for some Monster wacom or TXRX duplexers that can handle a | bazilion watts do not need to be posted, besides, I probably wouldn't be | able to afford ANY used wacom or txrx duplexer sets. | > >> | > | > Here is some reality: | > There is no such thing as cheap abundant duplexers for 600 kc 2 meter | > repeaters. | > If you cannot afford a good duplexer for your repeater, maybe consider | > taking up a different part of the hobby. Sorry to be so blunt, but too | > many folks think you can kludge a repeater system together with junk and | > have a really good working system. While there are a few of us here on | > the list that are likely talented enough to make something work from | > junk, that isn't the rule, rather the exception. Do yourself a favor | > and spend the money on a damn good duplexer as you will kick yourself | > every time you have desense you cannot overcome because of inadequate | > duplexer isolation. | > | > | | | | | | | | Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/ | | --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.535 / Virus Database: 330 - Release Date: 11/1/2003 Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Re: VHF Duplexer needed
I agree with Kevin. All too often one hears someone say they have everything they need to make a repeater, except for a duplexer. They expect to use a piece of crap antenna, too. Spend your money on a good duplexer and good antenna. The other stuff is the cheap stuff. The antenna and duplexer are the two most important components of a repeater system by far. Chuck WB2EDV > ><[EMAIL PROTECTED]> wrote: > > > > > >>I'm building a VHF high band repeater... on a tight budget. I have everything except a duplexer. I need some recomendations on cheap abundant duplexers that will do the 600Khz split. Max power I'll be using is 50 - 75W so recomendations for some Monster wacom or TXRX duplexers that can handle a bazilion watts do not need to be posted, besides, I probably wouldn't be able to afford ANY used wacom or txrx duplexer sets. > >> > > Here is some reality: > There is no such thing as cheap abundant duplexers for 600 kc 2 meter > repeaters. > If you cannot afford a good duplexer for your repeater, maybe consider > taking up a different part of the hobby. Sorry to be so blunt, but too > many folks think you can kludge a repeater system together with junk and > have a really good working system. While there are a few of us here on > the list that are likely talented enough to make something work from > junk, that isn't the rule, rather the exception. Do yourself a favor > and spend the money on a damn good duplexer as you will kick yourself > every time you have desense you cannot overcome because of inadequate > duplexer isolation. > > Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] VHF Duplexer needed
Another thought, on the CHEEP, use 2 antennas and 2 feedlines with 50 ft of vertical seperation and band reject single cavities in the TX and RX lines - might be cheaper. ssb - Original Message - From: "Ralph Mowery" <[EMAIL PROTECTED]> To: Sent: Monday, November 03, 2003 5:55 AM Subject: Re: [Repeater-Builder] VHF Duplexer needed | --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.535 / Virus Database: 330 - Release Date: 11/1/2003 Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] VHF Duplexer needed
I have taken some 10" Sinclair VHF cavities and copied the harnass from from a 6" store bought duplexer, except instead of a tunable capacitor made from polystyrene and tubing, I used a length of coax for the notch tuning, snip, snip watch for the dip on the spectrum display unit. The harnass alone cost around $150 for type N fittings and T fittings. For reference, I saw a WP641 in NEW condition go for $500 at the Belton TX hamfest. ssb - Original Message - From: "Ralph Mowery" <[EMAIL PROTECTED]> To: Sent: Monday, November 03, 2003 5:55 AM Subject: Re: [Repeater-Builder] VHF Duplexer needed --- Outgoing mail is certified Virus Free. Checked by AVG anti-virus system (http://www.grisoft.com). Version: 6.0.535 / Virus Database: 330 - Release Date: 11/1/2003 Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] VHF Duplexer needed
> I'm building a VHF high band repeater... on a tight budget. I have > everything except a duplexer. I need some recomendations on cheap > abundant duplexers that will do the 600Khz split. Max power I'll be > using is 50 - 75W so recomendations for some Monster wacom or TXRX > duplexers that can handle a bazilion watts do not need to be posted, > besides, I probably wouldn't be able to afford ANY used wacom or txrx > duplexer sets. > > If you have something low cost that can work or if you know of > something cheap that can work, let me know. There is almost no such thing as a low cost duplexer for 2 meters. It is probably the most expensive piece of the repeater. If you have the time and skills there have been some plans published but they must be in a building where the temperature does not change very much. There are some inexpensive duplexers for the 440 band . You may be beter off there on a limiated budget. The comercial 150 mhz band used a much wider split than the hams were allowed. The 440 band and the nearby comercial band usually use a 5 mhz split and the duplexers were much smaller and cheeper. Even going from a 10 watt repeater to a 100 watt repeater is only 10 db and that is not much when you need about 80 to 100 db worth of isolation. It is not usually the ammout of power at 2 meters but the total isolation that is where the big money comes in. With a little work the repeaters can be made very inexpensive tuil you add a good antenna, feedline and duplexer. Almost no one thinks of this when thy start out with the radio and controler. I have put together repeaters for about $ 300 to $ 400 each for the electronics and then spent that much or more for the antenna system and much more for a duplexer. Your use of Yahoo! Groups is subject to http://docs.yahoo.com/info/terms/
