[Repeater-Builder] Re: subaudibe tones..
W.r.t. early homebrew encoders, I never really liked the 555 version because of the non-sinewave output. Since the encoder need to cover more than an octave, fixed filtering of any kind couldn't be used to clean it up. You can find the 555 used as a pretty good tone generator in many a circuit, including a fair number of dtmf pads. If you look at the circuit on the sonic web page you'll notice the low pass filter, which works pretty well. Even with the values shown I found the described circuit puts out a lot more audio than required for a typical radio so after all the filtering you still had a high value resistor in series to knock the level down. So I went with the XR2206 function generator which put out a nice clean sine wave. Only other problem was frequency stability: Advantage to the 555, which by nature of design and operation is relatively immune to voltage and temp drift with more than a reasonable amount of change. only many years later after spending much time effort looking for the most stable Rs Cs did I discover when trying to build a 1000 Hz sine generator that the chip temperature affects the operating frequency. Never had much of a a problem with the 555 and the circuit is dirt cheap to build. cheers, s.
Re: [Repeater-Builder] Re: subaudibe tones..
If you S1 is like mine Chuck, do you remember the low battery alert - the user could not hear it, but everyone else could ? steve - former S1 owner. Chuck Kelsey wrote: Yep. That's what I did, added a ComSpec encoder to my 4AT. My Tempo S1 has the added encode with DIP switch. Both radios work fine today. Chuck WB2EDV
Re: [Repeater-Builder] Re: subaudibe tones..
A trick I used years ago for audio FSK RTTY on two meters was to put a frequency divider behind the 555. Generating the 2125 and 2295 frequencies for transmitting was done at 10 times the freq in the 555, and a resistor was switched in the 555 timing circuit to shift the frequency. Doing it this way allowed the non-synchronous RTTY signal to modulate the tone frequency without generating excessive clicks or transients in the audio output. A good sine wave output was guaranteed by simply using a low pass filter on the output of the square wave generated from this circuit. A single transition would be of a different frequency somewhere between 2125 and 2295, depending on just where the RTTY signal went from mark to space. 73 - Jim W5ZIT skipp025 [EMAIL PROTECTED] wrote: W.r.t. early homebrew encoders, I never really liked the 555 version because of the non-sinewave output. Since the encoder need to cover more than an octave, fixed filtering of any kind couldn't be used to clean it up. You can find the 555 used as a pretty good tone generator in many a circuit, including a fair number of dtmf pads. If you look at the circuit on the sonic web page you'll notice the low pass filter, which works pretty well. Even with the values shown I found the described circuit puts out a lot more audio than required for a typical radio so after all the filtering you still had a high value resistor in series to knock the level down. So I went with the XR2206 function generator which put out a nice clean sine wave. Only other problem was frequency stability: Advantage to the 555, which by nature of design and operation is relatively immune to voltage and temp drift with more than a reasonable amount of change. only many years later after spending much time effort looking for the most stable Rs Cs did I discover when trying to build a 1000 Hz sine generator that the chip temperature affects the operating frequency. Never had much of a a problem with the 555 and the circuit is dirt cheap to build. cheers, s. - Luggage? GPS? Comic books? Check out fitting gifts for grads at Yahoo! Search.
[Repeater-Builder] ltr repeater system
Hello group. Just looking at putting up a ltr system. I would like to go 2 channels for now just to see how it all works. My plan is to use it for my business plus sublease some space to other companies. Has anyone here ever tried a 2 channel ltr system before? How does it work compaired to a larger system? A tech over at trident told me not to waste my time with a 2 channel system as he said it would not work but I have talked to other people who have done 2 channel systems and like them. Thanks in advance for your help. wd
Re: [Repeater-Builder] Re: subaudibe tones..
Any new repeater coordination in Texas MUST have CTCSS or DCS access, no exception. Only older coordinations are grandfathered with open squelch access. It just does not make any sense to put on a repeater these days without some kind of access control. Unfortunately, some hams equate access control to a 'closed' system. That kind of thinking needs to go the way of AM phone :-) 73 - Jim W5ZIT Mark [EMAIL PROTECTED] wrote: I do remember that the Icom 02AT had subaudiable tone as an encode (TX) function over 20 years ago. As to the repeaters, it has and continues to be an owner option in most areas of the US. I don't there is a real date as to when it was introduced in repeaters. Mark KS4VT --- In Repeater-Builder@yahoogroups.com, larry allen [EMAIL PROTECTED] wrote: Does anyone know when subaudabe tones were introduced into ham radio repeaters.. or more specifically when they became standard in ham radio sets? Larry ve3fxq - Choose the right car based on your needs. Check out Yahoo! Autos new Car Finder tool.
Re: [Repeater-Builder] Re: subaudibe tones..
Yep. - Original Message - From: Steve S. Bosshard (NU5D) [EMAIL PROTECTED] To: Repeater-Builder@yahoogroups.com Sent: Tuesday, August 28, 2007 8:54 AM Subject: Re: [Repeater-Builder] Re: subaudibe tones.. If you S1 is like mine Chuck, do you remember the low battery alert - the user could not hear it, but everyone else could ? steve - former S1 owner. Chuck Kelsey wrote: Yep. That's what I did, added a ComSpec encoder to my 4AT. My Tempo S1 has the added encode with DIP switch. Both radios work fine today. Chuck WB2EDV Yahoo! Groups Links
Re: [Repeater-Builder] Re: subaudibe tones..
The 555 has been used for many timer applications. However, it timing is controlled with and RC network and these are difficult to keep within any tight accuracy like that of DTMF encoding. Besides there are plenty of xtal controlled devices for this. And as you said the output is a square wave, not always desirable for audio. However, does make a pretty clock for digital circuits. There are many applications the 555 can be used for. 73, ron, n9ee/r From: skipp025 [EMAIL PROTECTED] Date: 2007/08/28 Tue AM 06:27:32 CDT To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: subaudibe tones.. W.r.t. early homebrew encoders, I never really liked the 555 version because of the non-sinewave output. Since the encoder need to cover more than an octave, fixed filtering of any kind couldn't be used to clean it up. You can find the 555 used as a pretty good tone generator in many a circuit, including a fair number of dtmf pads. If you look at the circuit on the sonic web page you'll notice the low pass filter, which works pretty well. Even with the values shown I found the described circuit puts out a lot more audio than required for a typical radio so after all the filtering you still had a high value resistor in series to knock the level down. So I went with the XR2206 function generator which put out a nice clean sine wave. Only other problem was frequency stability: Advantage to the 555, which by nature of design and operation is relatively immune to voltage and temp drift with more than a reasonable amount of change. only many years later after spending much time effort looking for the most stable Rs Cs did I discover when trying to build a 1000 Hz sine generator that the chip temperature affects the operating frequency. Never had much of a a problem with the 555 and the circuit is dirt cheap to build. cheers, s. Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
[Repeater-Builder] Re: ltr repeater system
Hello back, Of course the Trident guy would tell you not to try a two channel LTR setup... they sell and service a competing product. A 2 Channel LTR System is a wonderful thing versus 2 channels of conventional radio. Over the same average amount of time many different business users can access the radio system and they should never hear each others conversations. Solves two major user issues without even trying hard. The most practical value LTR Controller is probably the CSI Brand LT-4200 unit. You have a very good idea... been there, done (actually now doing) that and already have the coffee mug and Tee Shirt to prove it. cheers, skipp wadeds2003 [EMAIL PROTECTED] wrote: Hello group. Just looking at putting up a ltr system. I would like to go 2 channels for now just to see how it all works. My plan is to use it for my business plus sublease some space to other companies. Has anyone here ever tried a 2 channel ltr system before? How does it work compaired to a larger system? A tech over at trident told me not to waste my time with a 2 channel system as he said it would not work but I have talked to other people who have done 2 channel systems and like them. Thanks in advance for your help. wd
[Repeater-Builder] Re: subaudibe tones..
You mean to tell us there are so many repeaters on the air in Texas that even the low population rural area repeaters must operate constant ctcss? CTCSS operational control is a nice idea when there is a need. Otherwise it can and does turn people away quite fast. The saving grace is at least most newer radios have a built in ctcss encoder. Is your repeater coordination group run by a lot of wanna'be radio politician types? Do the coordination people in power seem to linger around and rarely change out of office? (ie the same group of people rotate through the same elected coordinator positions?) Is there a slight hint of a coordinated fishy smell in your area? :-) cheers, s. Any new repeater coordination in Texas MUST have CTCSS or DCS access, no exception. Only older coordinations are grandfathered with open squelch access. It just does not make any sense to put on a repeater these days without some kind of access control. Unfortunately, some hams equate access control to a 'closed' system. That kind of thinking needs to go the way of AM phone :-) 73 - Jim W5ZIT
Re: RE: [Repeater-Builder] Duplexers
Gary, Transforming from a load to 50 Ohm resistive depends on the load impedance. Same for other impedances. Going from a load to another resistive load will always be a the ratio of N:50. So 50 Ohm coax could transform say a 75 OHM load to a 75:50 or 50:75 ratio. 75 Ohm load with 1/4 wave 50 Ohm coax to 33 Ohms, but not anything. At 1/2 wave back to 75 Ohm. In between would be R with j component, inductive or capacitive depending on length. A Smith Chart shows this. So converting the load to what you want would normally require a different cable impedance. The wiring harnesses used in multi-element antennas like the DB224 4 bay dipole antenna use cable type to convert each antenna load to a 50 Ohm input. In this case there are actually 3 harnesses, one for each of 2 dipole sets and then a 3rd to take these two to one input. I think 92 or 62 Ohm cable is used, but not sure. 73, ron, n9ee/r From: Gary Schafer [EMAIL PROTECTED] Date: 2007/08/27 Mon PM 10:52:11 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Duplexers   From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Jesse Lloyd Sent: Monday, August 27, 2007 9:39PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder]Duplexers  If your coax is the sameimpedance as your transmitter, but different than your load, can it still be atransformer though? Is it possible to transform a load that isn't 50 ohmsto 50 ohms using 50 ohm coax?  Yes italways acts as a transformer when the load impedance is not the same as thecoax impedance. You cannot transform any impedance to 50 ohms with a 50 ohm cable. You can transformto something above or below the 50 ohm cable impedance. Thereason changing the length of the coax to a transmitter helps sometimes, eventhough the transformation of impedance is not to 50 ohms, is that thetransmitter may see an impedance that it is happier with than what the originaltransformed impedance was. Yes your right VSWR is the ratio between Vmax and Vmin, node and anodes, of theinterference pattern caused by standing waves. Even still there is apoint where the voltage is at a minimum on the line. What happens if thatpoint is at the transmitters output... does it help keep the heat down in thetransmitter due to high SWR?  It doesnâtmatter where the min and max are on the line. The same amount of reflectedpower will be seen at any point. Reflected power does NOT get back into thetransmitter. It gets re-reflected back towards the antenna when it reaches thetransmitter circuits. If youhave a 100 watt transmitter with 10 watts reflected from the load yourwattmeter will read 110 watts forward and 10 watts reflected. The extra 10watts forward power comes from the 10 watts that is reflected from the load andre-reflected at the transmitter. The re-reflected power adds to the original100 watts forward power for a total of 110 watts forward power. All of the 100watts eventually gets radiated by the antenna. This is of course disregardingany line loss which would lower the reflected power indication by the amount ofline loss. Line loss would also claim a portion of the re-reflected power too. If youhave two watt meters and an antenna matching device you can put one wattmeter betweenthe transmitter and the matching device and tune it for minimum reflected poweron the first meter. Then with a second meter between the tuner and themismatched load you can see the second wattmeter that is reading the reflectedpower. The second wattmeter will have a higher forward power reading than thefirst due to the added re-reflected power.  With amismatched load the transmitter may run hotter because it is under oroverloaded due to the non 50 ohm load that it is seeing but it is notdissipating any of the reflected power. Many solid state transmitters aresensitive to reactive loads and may draw more current because of this.  73 Gary K4FMX On 8/27/07, GarySchafer [EMAIL PROTECTED]wrote: VSWR (voltage standingwave ratio) will be the same at any point on a transmission  line. Theimaginary standing wave does not move as the forward and reflected power does.The voltage standing wave ratio is the ratio of the forward voltage to thereflected voltage at a given point on the line. As you move up or down the linethe forward voltage will change and so will the reflected voltage but the ratioor difference between the two will work out to the same value. Thus the termstanding wave. The wave appears to stand still on the line as itoscillates up and down in a sin wave manor.  As Jeff has said theimpedance shown to the transmitter will be different with different lengths oftransmission line only if the load is not a perfect 50 ohms assuming a 50 ohmline. With a load that does not match the line the line operates as animpedance transformer. Think about what a quarter wave length line looks likewith a
[Repeater-Builder] Re: subaudibe tones..
Per the 555 Timer Chip Data Sheet Operation Description: The 555 operational time values depends mostly on the ratio of voltage set-points and remains relatively free from most of the typical issues experienced with external rc networks and feedback type oscillators. Before there was really low cost crystal referenced tone generators there was a number of both well done 555 DTMF and 555 CTCSS tone generation circuits that worked without a hitch. 555 output Square waves should look just fine when filtered for audio at the end of a simple low cost rc network. Working 555 examples include the ctcss generator shown on the sonic web page. The Heathkit DTMF mic available with their early 2-meter kit radios. The gazillion made Heathkit Code Practice Oscillators. One nice thing about the 555 chip is the available output easily drives low impedance loads quite well. Also makes a nice oscillator to generate voltages independent of the package supply. Some 70's vintage radios used the 555 chip to generate a negative rail supply for those early eprom, prom and op-amp circuits. Quite the problem solving work-horse device and it has a practical use as a pretty good audio oscillator. cheers, s. The 555 has been used for many timer applications. However, it timing is controlled with and RC network and these are difficult to keep within any tight accuracy like that of DTMF encoding. Besides there are plenty of xtal controlled devices for this. And as you said the output is a square wave, not always desirable for audio. However, does make a pretty clock for digital circuits. There are many applications the 555 can be used for. 73, ron, n9ee/r From: skipp025 [EMAIL PROTECTED] Date: 2007/08/28 Tue AM 06:27:32 CDT To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: subaudibe tones.. W.r.t. early homebrew encoders, I never really liked the 555 version because of the non-sinewave output. Since the encoder need to cover more than an octave, fixed filtering of any kind couldn't be used to clean it up. You can find the 555 used as a pretty good tone generator in many a circuit, including a fair number of dtmf pads. If you look at the circuit on the sonic web page you'll notice the low pass filter, which works pretty well. Even with the values shown I found the described circuit puts out a lot more audio than required for a typical radio so after all the filtering you still had a high value resistor in series to knock the level down. So I went with the XR2206 function generator which put out a nice clean sine wave. Only other problem was frequency stability: Advantage to the 555, which by nature of design and operation is relatively immune to voltage and temp drift with more than a reasonable amount of change. only many years later after spending much time effort looking for the most stable Rs Cs did I discover when trying to build a 1000 Hz sine generator that the chip temperature affects the operating frequency. Never had much of a a problem with the 555 and the circuit is dirt cheap to build. cheers, s. Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: [Repeater-Builder] Re: subaudibe tones..
At 8/28/2007 04:27, you wrote: W.r.t. early homebrew encoders, I never really liked the 555 version because of the non-sinewave output. Since the encoder need to cover more than an octave, fixed filtering of any kind couldn't be used to clean it up. You can find the 555 used as a pretty good tone generator in many a circuit, including a fair number of dtmf pads. If you look at the circuit on the sonic web page you'll notice the low pass filter, which works pretty well. Even with the values shown I found the described circuit puts out a lot more audio than required for a typical radio so after all the filtering you still had a high value resistor in series to knock the level down. Still, you can't build an effective LPF for it. Best you could do would be to put a 6 dB/octave LPF that broke around 2 x 67 Hz, let the higher tone frequencies get rolled off. Either way, you still get buz... So I went with the XR2206 function generator which put out a nice clean sine wave. Only other problem was frequency stability: Advantage to the 555, which by nature of design and operation is relatively immune to voltage and temp drift with more than a reasonable amount of change. I never found the 555 to be very stable; the XR2206 always did better. Bob NO6B
[Repeater-Builder] Re: subaudibe tones..
Still, you can't build an effective LPF for it. Best you could do would be to put a 6 dB/octave LPF that broke around 2 x 67 Hz, let the higher tone frequencies get rolled off. Either way, you still get buz... Do you assume multiple frequency operation? I set the oscillator to one frequency and park it inside the radio. Place the sonic page described or similar rc filter in line and try the circuit. You'll find it works pretty well for what it is... the only buz that makes it to and through most modulators is pretty much only the desired ctcss frequency. I've never experienced a case where the delivered audio was objectionable. I never found the 555 to be very stable; the XR2206 always did better. Bob NO6B But the 2206 tends to be much less tolerant of voltage and temp changes as found in 99% plus mobile radio operations. Otherwise a great chip for what it is... I wouldn't have put the 555 ctcss encoder circuit on the sonic web page unless I was sure it was a well tested design that worked really well. I haven't had to build one in a number of years but we cranked out a few hundred back in the day... never a failure or complaint. Sure there are better ctcss generator alternatives but probably not for the price and performance of the described 555 encoder circuit. cheers, skipp
RE: [Repeater-Builder] Duplexers
If your coax is the same impedance as your transmitter, but different than your load, can it still be a transformer though? It will ALWAYS act as a transformer when the cable's Z does not match the LOAD Z. The SOURCE device (transmitter) plays NO part in the transformation that happens. The Z at the source end of the line is a function of only three things: the load Z (antenna, duplexer, whatever), the cable's characteristic Z, and the cable's electrical length (in degrees/wavelengths/radians/whatever). Cable loss also plays into it, as its effect is to always bring the load Z closer to the cable's characteristic Z as cable loss goes up, but let's leave that out for the sake of simplicity. The source device's impedance does not factor into the equation at all when it comes to determining what the resultant Z is at the source end of the line. Any mismatch that occurs at that end of the line (the source/transmitter end) does NOT affect the VSWR on the line, nor does it change the Z at the source end of the line. It's very important to not put the cart before the horse here. While it may seem to be contrary to instinct, the device that is sourcing the power is NOT what determinates what happens on the transmission line with respect Z and VSWR, it's the LOAD mismatch that sets up the standing waves and the resulting Z's along the length of the line. It is for this reason that your transmitter CANNOT detune your duplexer, and for the same reason, you can't tune (change the Z) of your antenna from the far end of the cable. Is it possible to transform a load that isn't 50 ohms to 50 ohms using 50 ohm coax? NO. Yes your right VSWR is the ratio between Vmax and Vmin, node and anodes, of the interference pattern caused by standing waves. Even still there is a point where the voltage is at a minimum on the line. What happens if that point is at the transmitters output... does it help keep the heat down in the transmitter due to high SWR? NO. VSWR on a transmission line doesn't directly manifest as heat in a transmitter. The whole notion of high VSWR creating heat in a transmitter is likely based on a drop in efficiency in SOME transmitters when they are not properly matched to the feedline. You can have a very high VSWR on the feedline, and provided the transmitter is matched to the Z at the source end of the line, the efficiency will not suffer, and there will be nother ill effects (including heating) that occur within the transmitter. A PROPER MATCH DOES NOT OCCUR WHEN THE TRANSMITTER'S SOURCE Z IS THE SAME AS THE CABLE'S CHARACTERISTIC Z EXCEPT WHEN THE LOAD Z ALSO MATCHES THE CABLE'S CHARACTERISTIC Z. Or, rewritten, if the load Z (antenna) is not 50+j0, a 50 ohm transmitter delivering power into a 50 ohm transmission line will NEVER be matched. (Didn't mean to shout, but it's important to understand and accept that fact.) Sidebar: VSWR is a conveniently-simplistic scalar value, but it doesn't tell you anything about the specific impedance at a particular point along the line, nor what the ratio and phase relationships are between voltage and current. You can calculate VSWR based on a specific Z, but you can't do the reverse, except in the case of a true 1:1 VSWR. All Corvettes are Chevys, but not all Chevys are Corvettes. You get the idea. Many hams like to talk in terms of VSWR as it's a nice easy number to deal with, and the lower the number, the better. But that oversimplification seems to also translate into a relaxation in the attention paid to the theory behind what's really going on along the transmission line, at the source-to-line interface, and at the line-to-load interface. When it really comes down to the nuts and bolts of designing and building matching networks, you don't care about the VSWR value, you need to know, think, and design based on complex impedances. Back in the good ol' days when your rig running 6146's had a pi matching network on its output, you could tune the transmitter into some not-so-good loads, often in excess of 3:1 VSWR, without any problem. Why? The pi network did its job, matching the high-Z (and somewhat reactive) output Z of the tubes to the whatever-Z existed at the end of the antenna feedline. You could get efficiency just as good at a 3:1 VSWR as you could at 1:1 because the output of the matching network provided a conjugate match. --- Jeff
[Repeater-Builder] LTR Rocks !
Kinda off track for a Ham repeater group, but been there done that. Mine was due to loss of 800 SMR channels when they were easy to come by, then later impossible to get due to freezes. Exclusivity. You need at least one repeater that has exclusive use in a service area because LTR uses centralized control and the HOME repeater needs to be exclusive. Having the second repeater also exclusive is a big plus. Next narrowband vs wideband. Depending on location you may be narrow band - that seems to work OK. You need two repeaters and controllers. Some repeaters like the Johnson VX have logic built in. Others use IDA, RLC, Trindent, Zetron Model 42, etc. You should be able to handle 6 to 10 groups of 10 to 15 radios pretty comfortably - probably more. The curve for users vs channels is exponential as adding a channel makes much more capacity than one channel by itself. Best success, Steve NU5D wadeds2003 wrote: Hello group. Just looking at putting up a ltr system. I would like to go 2 channels for now just to see how it all works. My plan is to use it for my business plus sublease some space to other companies. Has anyone here ever tried a 2 channel ltr system before? How does it work compaired to a larger system? A tech over at trident told me not to waste my time with a 2 channel system as he said it would not work but I have talked to other people who have done 2 channel systems and
[Repeater-Builder] Cushman CE-15 Spectrum Analyzer
I have a Cushman CE-15 Spectrum Analyzer that was working and recently I noticed signals very weak. When measured they are 30dB down. I have checked the Diodes in the RF attenuator and they check good. I noticed the schematic I got off the repeater builders WEB page that the ref level switch does not correspond to what I measure on the 4 lines going to the RF attenuator. The Cushman I have is black in color on the face. The switch going to the IF switchable gain and BW check out ok. Any idea where else to look for the 30dB loss? Anyone have a good schematic on this spectrum analyzer? I am borrowing another spectrum analyzer to look closer at the RF attenuator to see if the diodes are leaky. No RF was transmitted into the Cushman. Thanks; David WA4ECM
[Repeater-Builder] OT: ICOM IC-730 current pricing
Hi to the groups, I recently acquired an ICOM IC-730 through an estate. I have someone interested in buying the unit, but I'm not sure what the selling price should be. It's in good condition and from what I can determine all of the functions work. The serial number is in the 12,000 range. I called AES here in Milwaukee; they couldn't provide a cost estimate. They did suggest that I look on E-BAY to see if there was anyone selling one, but no luck there. I did a Google search and did find a couple of hits - one article stated that the current pricing was between $200.00 and $275.00. Anyone have any other ideas how to determine the price range? My only goal here is to sell the unit at a fair price. TIA, Don, KD9PT don at httpd dot org
Re: [Repeater-Builder] OT: ICOM IC-730 current pricing
You do a feebay seach and check the completed auctions box http://search-completed.ebay.com/ic-730_W0QQ_trksidZm37QQcatrefZC5QQfbdZ1QQfclZ3QQfisZ2QQflocZ1QQfposZ75028QQfromZR6QQfrppZ50QQfsooZ1QQfsopZ1QQfssZ0QQftrtZ1QQftrvZ1QQnojsprZyQQpfidZ0QQsaaffZafdefaultQQsabfmtsZ0QQsacatZQ2d1QQsacqyopZgeQQsacurZ0QQsadisZ200QQsaobfmtsZexsifQQsargnZQ2d1QQsaslcZ0QQsaslopZ1QQsatitleZicQ2d730QQsofocusZbs Don Kupferschmidt wrote: Hi to the groups, I recently acquired an ICOM IC-730 through an estate. I have someone interested in buying the unit, but I'm not sure what the selling price should be. It's in good condition and from what I can determine all of the functions work. The serial number is in the 12,000 range. I called AES here in Milwaukee; they couldn't provide a cost estimate. They did suggest that I look on E-BAY to see if there was anyone selling one, but no luck there. I did a Google search and did find a couple of hits - one article stated that the current pricing was between $200.00 and $275.00. Anyone have any other ideas how to determine the price range? My only goal here is to sell the unit at a fair price. TIA, Don, KD9PT don at httpd dot org mailto:[EMAIL PROTECTED] -- Jay Urish CCNANetwork Engineer Home)972-691-0125 Cell)972-965-6229
Re: [Repeater-Builder] Duplexers
Jeff DePolo wrote: NO. VSWR on a transmission line doesn't directly manifest as heat in a transmitter. The whole notion of high VSWR creating heat in a transmitter is likely based on a drop in efficiency in SOME transmitters when they are not properly matched to the feedline. Or worse, a transmitter that when feeding anything other than its design Z starts throwing spurs. In that case, it's output filters (if it has any!) may be eating all that spur power... because folks set power AFTER the final low-pass filter. I could see that being another possible way you'd get transmitter heating if things were mismatched. It wouldn't be as significant as the whole PA getting inefficient, though. Jeff also already mentioned (and set aside for purposes of this discussion) transmitters that have built-in directional couplers and loads that are mounted to a common heatsink with the PA transistors. Moto likes to do this on most of their continuous-duty PA's. That can cause heating too, if reflected power is high, but it's not relevant to the discussion at hand, because it's not the transmitter heating up, it's the load hanging off of the directional coupler. Nate WY0X
Re: [Repeater-Builder] Re: subaudibe tones..
skipp025 wrote: You mean to tell us there are so many repeaters on the air in Texas that even the low population rural area repeaters must operate constant ctcss? Not sure about Texas, but here anyway -- the requirement is there that the repeater must at least HAVE the ability to switch on CTCSS, and the coordination is based on the CTCSS being active, as it relates to co-channel interference. Any organization can choose to turn off their CTCSS decoder, but the repeater must be CAPABLE of it, to gain a new coordination, generally. CTCSS operational control is a nice idea when there is a need. Otherwise it can and does turn people away quite fast. The saving grace is at least most newer radios have a built in ctcss encoder. If CTCSS is still turning people away after almost 40 years of it being out there and in heavy use for at least 30 years, perhaps they need to be. :-) Is your repeater coordination group run by a lot of wanna'be radio politician types? Do the coordination people in power seem to linger around and rarely change out of office? (ie the same group of people rotate through the same elected coordinator positions?) Is there a slight hint of a coordinated fishy smell in your area? Ahh yes, the evil repeater coordinator thread needs to get going again, definitely. Demonizing coordinators is a favorite past-time of all. Grab the popcorn and pull up a chair! (Not withstanding that it's obvious that Texas has... what's the politically correct term here? Issues. Lawsuits, egos, etc... all going on down in the great state of Texas. No big surprise there.) The thread that doesn't start up often is the thread pointing out that 99.99% of repeater owners couldn't be bothered to volunteer to work on a coordination body, if you asked them. Demonizing coordinators doesn't get anyone anywhere. Volunteers needed. Non-insane, smart-thinking volunteers, needed even more badly. :-) Double :-) :-) Nate
[Repeater-Builder] Re: subaudibe tones..
Not sure about Texas, but here anyway -- the requirement is there that the repeater must at least HAVE the ability to switch on CTCSS, and the coordination is based on the CTCSS being active, as it relates to co-channel interference. The smart way to go... Any organization can choose to turn off their CTCSS decoder, but the repeater must be CAPABLE of it, to gain a new coordination, generally. More than reasonable. If CTCSS is still turning people away after almost 40 years of it being out there and in heavy use for at least 30 years, perhaps they need to be. In rural and remote areas it often ends up a bit of chore for traveling-through mobiles to locate the proper rx ctcss. Unless an area visitor already knows about the available repeater most open machines are easily missed. Ahh yes, the evil repeater coordinator thread needs to get going again, definitely. Demonizing coordinators is a favorite past-time of all. Grab the popcorn and pull up a chair! Monday group posts require a modest blood pressure stimulate. (Not withstanding that it's obvious that Texas has... what's the politically correct term here? Issues. Lawsuits, egos, etc... all going on down in the great state of Texas. No big surprise there.) And here I thought it was a local phenomena. The thread that doesn't start up often is the thread pointing out that 99.99% of repeater owners couldn't be bothered to volunteer to work on a coordination body, if you asked them. Not the case up here... many good folks try but the same general circle of people often seem to cycle through the coordination group before they depart in haste for one or more reasons. Demonizing coordinators doesn't get anyone anywhere. Volunteers needed. Non-insane, smart-thinking volunteers, needed even more badly. An Amen from the crowd... we sometimes have a fairly good coordination crowd who often seem to be overwhelmed by the task. I've been told that dealing with Hams in not always easy... cheers, s.
Re: [Repeater-Builder] Re: ltr repeater system
I have to agree with what Skip said. The big issue with LTR (and other trunking formats) is that you have to either 1)have an exclusive license for each channel for the area you want to cover (may be hard to find, and licensing is expensive once you do), or 2) put monitor rx's on each OUTPUT freq. at the site with a cross busy to keep that channel from being assigned when someone else is using it down the road. The CSI unit Skip mentioned does have that provision, among most others. -- Jim Barbour WD8CHL
Re: [Repeater-Builder] Re: subaudible tones..
At 8/28/2007 09:26 AM, you wrote: Still, you can't build an effective LPF for it. Best you could do would be to put a 6 dB/octave LPF that broke around 2 x 67 Hz, let the higher tone frequencies get rolled off. Either way, you still get buz... Do you assume multiple frequency operation? Yes. I set the oscillator to one frequency and park it inside the radio. Place the sonic page described or similar rc filter in line and try the circuit. You'll find it works pretty well for what it is... the only buz that makes it to and through most modulators is pretty much only the desired ctcss frequency. I've never experienced a case where the delivered audio was objectionable. Well, I did in every case. Not surprising, as there's a lot of odd harmonic content within a square wave; I suppose the lack of a 2nd harmonic helps your LPF design a little. Plus if you're feeding a phase modulator, you've got another 6 dB/octave working against you. Perhaps you were feeding direct FM modulators using higher CTCSS freqs.? Perhaps it's a difference of perception. Back in the day, there was a rather high emphasis (pun quasi-intended) on PL tone purity. If your encoder had any harmonic content others let you know. In addition, some of the repeaters around here seemed to 'emphasize' the PL harmonics for some reason, as they sounded worse through the repeater than when heard directly. I never found the 555 to be very stable; the XR2206 always did better. Bob NO6B But the 2206 tends to be much less tolerant of voltage and temp changes as found in 99% plus mobile radio operations. Otherwise a great chip for what it is... From the respective data sheets: drift w/temperature (typical): LM555: 150 PPM/°C XR2206: 20 PPM/°C drift w/supply LM555: 0.3%/V XR2206: 0.01%/V Looking at the drift specs, it looks like all my drift problems with the XR2206 were likely limited to the Rs Cs used, as even a 50 °C change would only result in a typical 0.1 Hz drift @ 100.0 Hz (due only to the chip). Bob NO6B
Re: [Repeater-Builder] LTR Rocks !
Steve S. Bosshard (NU5D) wrote: Kinda off track for a Ham repeater group, but been there done that. Mine was due to loss of 800 SMR channels when they were easy to come by, then later impossible to get due to freezes. Exclusivity. You need at least one repeater that has exclusive use in a service area because LTR uses centralized control and the HOME repeater needs to be exclusive. Not quite true. LTR does not use a control channel, and does not transmit continuously, however, if you do not have exclusivity on a channel-ANY channel-you need a monitor rx on the output cross-connected so that it prevents that channel from keying if it hears other traffic. Having the second repeater also exclusive is a big plus. Next narrowband vs wideband. Depending on location you may be narrow band - that seems to work OK. 512 MHz and down to 136 or whatever will all be narrowband by 2013 anyway, except I haven't seen provisions for it for part 95 (GMRS) yet, so it will likely be exempt. -- Jim Barbour WD8CHL
Re: [Repeater-Builder] Re: subaudibe tones..
At 8/28/2007 12:39 PM, you wrote: If CTCSS is still turning people away after almost 40 years of it being out there and in heavy use for at least 30 years, perhaps they need to be. In rural and remote areas it often ends up a bit of chore for traveling-through mobiles to locate the proper rx ctcss. Unless an area visitor already knows about the available repeater most open machines are easily missed. One concept that really helps in this area is CTCSS tone frequency standardization, IOW tones by region. All you then need to know is the freq. being used in the area you're traveling to. Many areas are already well established: 110.9 in Rochester NY, 107.2 in Niagara Falls San Diego, 131.8 in Santa Barbara, 127.3 in Springfield MA. Even if you don't know what tone is in use, all you have to do is find the tone of one system. After that you can find the others by kerchunking (with ID of course!) all the other pairs with that tone. Bob NO6B
Re: [Repeater-Builder] Re: ltr repeater system
An LTR mobile will try and access the repeater - short data transmissions, even if the base repeater's transmitter is inhibited. Some of the older stuff had to hear the data word from the repeater first in order to transmit, but newer radios, though they cannot handshake with a dead repeater, will try. Also if the home repeater is locked out, the subscriber units have no way to go to repeater 2 unless repeater 1 (locked out due to busy channel) tells the mobile to go to rept 2. So, you need at least one exclusive channel for the system to have any reasonable chance of working (or else use a very poor guard receiver.) Steve NU5D Jim wrote: I have to agree with what Skip said. The big issue with LTR (and other trunking formats) is that you have to either 1)have an exclusive license for each channel for the area you want to cover (may be hard to find, and licensing is expensive once you do), or 2) put monitor rx's on each OUTPUT freq. at the site with a cross busy to keep that channel from being assigned when someone else is using it down the road. The CSI unit Skip mentioned does have that provision, among most others.
Re: [Repeater-Builder] LTR Rocks !
LTR indeed does not use a dedicated control channel like EDACS or PP - control is distributed. Subscriber units are programmed to seek a HOME repeater and if it is not available (busy channel inhibit) the radios homed to that repeater are dead. When the home repeater is servicing a call it at the same time tells subscriber units to find a new home on RPT #X and will continue to send that data word even after the user on the home repeater is finished, so long as the transmission continues on the new home to service late entry. LTR is considered by the FCC as centralized trunking. De-Centralized trunking lets mobile units decide when to transmit. LTR does not have a provision for the mobile radios not to transmit on a busy channel. In centralized trunking, the site orchestrates mobile transmissions. But I may be wrong, Steve NU5D Jim wrote: Steve S. Bosshard (NU5D) wrote: Kinda off track for a Ham repeater group, but been there done that. Mine was due to loss of 800 SMR channels when they were easy to come by, then later impossible to get due to freezes. Exclusivity. You need at least one repeater that has exclusive use in a service area because LTR uses centralized control and the HOME repeater needs to be exclusive. Not quite true. LTR does not use a control channel, and does not transmit continuously, however, if you do not have exclusivity on a channel-ANY channel-you need a monitor rx on the output cross-connected so that it prevents that channel from keying if it hears other traffic. Having the second repeater also exclusive is a big plus. Next narrowband vs wideband. Depending on location you may be narrow band - that seems to work OK. 512 MHz and down to 136 or whatever will all be narrowband by 2013 anyway, except I haven't seen provisions for it for part 95 (GMRS) yet, so it will likely be exempt.
Re: [Repeater-Builder] Re: subaudibe tones..
Same in WPA... http://www.wprc.us/ctcss.htm The recently adopted CDCSS codes are not on the map yet. Joe M. Bob Dengler wrote: One concept that really helps in this area is CTCSS tone frequency standardization, IOW tones by region. All you then need to know is the freq. being used in the area you're traveling to.
RE: [Repeater-Builder] Re: ltr repeater system
Skip, If I can add my two cents in, use the Zetron controllers and your project will be much easer and work. Not knocking the other controllers, im sure there are plenty of good controllers but I just have the most experience with the Zetron controllers. Mike _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of skipp025 Sent: Tuesday, August 28, 2007 9:36 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: ltr repeater system Hello back, Of course the Trident guy would tell you not to try a two channel LTR setup... they sell and service a competing product. A 2 Channel LTR System is a wonderful thing versus 2 channels of conventional radio. Over the same average amount of time many different business users can access the radio system and they should never hear each others conversations. Solves two major user issues without even trying hard. The most practical value LTR Controller is probably the CSI Brand LT-4200 unit. You have a very good idea... been there, done (actually now doing) that and already have the coffee mug and Tee Shirt to prove it. cheers, skipp wadeds2003 [EMAIL PROTECTED] wrote: Hello group. Just looking at putting up a ltr system. I would like to go 2 channels for now just to see how it all works. My plan is to use it for my business plus sublease some space to other companies. Has anyone here ever tried a 2 channel ltr system before? How does it work compaired to a larger system? A tech over at trident told me not to waste my time with a 2 channel system as he said it would not work but I have talked to other people who have done 2 channel systems and like them. Thanks in advance for your help. wd
Re: [Repeater-Builder] Re: subaudibe tones..
PL access is a useful tool when all other means have been taken to get rid of undesirable audio artifacts on a repeater. Usually this includes harmonious coordination with the other users at a site and a knowledgeable technical approach to the problem. All to often though, mandatory PL is just a band aid to hide the lack of expertise of those concerned. Jack - N7OO - Original Message - From: Jim Brown To: Repeater-Builder@yahoogroups.com Sent: Tuesday, August 28, 2007 8:04 AM Subject: Re: [Repeater-Builder] Re: subaudibe tones.. Any new repeater coordination in Texas MUST have CTCSS or DCS access, no exception. Only older coordinations are grandfathered with open squelch access. It just does not make any sense to put on a repeater these days without some kind of access control. Unfortunately, some hams equate access control to a 'closed' system. That kind of thinking needs to go the way of AM phone :-) 73 - Jim W5ZIT Mark [EMAIL PROTECTED] wrote: I do remember that the Icom 02AT had subaudiable tone as an encode (TX) function over 20 years ago. As to the repeaters, it has and continues to be an owner option in most areas of the US. I don't there is a real date as to when it was introduced in repeaters. Mark KS4VT --- In Repeater-Builder@yahoogroups.com, larry allen [EMAIL PROTECTED] wrote: Does anyone know when subaudabe tones were introduced into ham radio repeaters.. or more specifically when they became standard in ham radio sets? Larry ve3fxq -- Choose the right car based on your needs. Check out Yahoo! Autos new Car Finder tool.
Re: [Repeater-Builder] Re: ltr repeater system
I have 14 channels at 3 sites running Johnson VX on 800 - they tell me the VX logic was developed by Trident. In 460 Waco is a 4 channel Uniden Esas, Temple is a 5 channel Uniden ESAS, and Killeen is 5 channel ESAS, Killeen and Temple were originally a mix of Ida RLC's and Zetron 42's - the 42' and RLC's never gave any trouble. Several other sites have a mix of 460 VX with on board logic and RLC's and Model 42's. Have somewhere around 50 channels of LTR running. Steve Mike Mullarkey wrote: Skip, If I can add my two cents in, use the Zetron controllers and your project will be much easer and work. Not knocking the other controllers, im sure there are plenty of good controllers but I just have the most experience with the Zetron controllers. Mike
[Repeater-Builder] Re: subaudible tones..
Do you assume multiple frequency operation? Yes. I never much cared to adapt the design to multi frequency aps but it was done. Most all the repeaters in our area use the same 127.3 ctcss tone. We did use a common 2 pole 6 position radio shack source rotary switch to select different adjustable pots (controls). It worked pretty well where needed. Well, I did in every case. Not surprising, as there's a lot of odd harmonic content within a square wave; I suppose the lack of a 2nd harmonic helps your LPF design a little. Plus if you're feeding a phase modulator, you've got another 6 dB/octave working against you. Perhaps you were feeding direct FM modulators using higher CTCSS freqs.? Just various older radios with the modulator of the day circuit. We used the lpf shown with some circuits by nature of their design also adding to the harmonic attenuation. Perhaps it's a difference of perception. Back in the day, there was a rather high emphasis (pun quasi-intended) on PL tone purity. You are right... I remember when I would have never thought to use a 555 as a tone generator. I have a number of pre-555 design, op amp ctcss circuits that never seemed to be really reliable... ie stable. Those darn feedback circuits with a mini light bulb installed. But the 555 circuit was/is always a winner... it works darn well for what it is. If your encoder had any harmonic content others let you know. In addition, some of the repeaters around here seemed to 'emphasize' the PL harmonics for some reason, as they sounded worse through the repeater than when heard directly. I would suspect the way both receiver ctcss voice audio is or is not properly handled is the key. I seem to find a lot of repeaters don't remove or reduce the received ctcss before sending the audio along... Any heavy audio compression just seems to make the ignored ctcss blow-through and harmonic problems much worse. Less we also forget how most current Amateur Radios arrive with smokin' hot deviation. I'm often surprised some of the circuits I run into even work as well as they appear to... Looking at the drift specs, it looks like all my drift problems with the XR2206 were likely limited to the Rs Cs used, as even a 50 °C change would only result in a typical 0.1 Hz drift @ 100.0 Hz (due only to the chip). Bob NO6B The Network RC Parts are most often the biggest sinner. Cheap caps and resistors keep the show moving along even if you don't want to travel that road. cheers Bob, s. ps: when we get done talking about the 555 ctcss encoder I've got a less popular 567 ctcss encoder/decoder circuit available.
[Repeater-Builder] Re: LTR Rocks !
Not quite true. LTR does not use a control channel, and does not transmit continuously, however, if you do not have exclusivity on a channel-ANY channel-you need a monitor rx on the output cross-connected so that it prevents that channel from keying if it hears other traffic. In the LTR world some people call the Home Repeater the Control Channel even if you use multiple home repeaters as programmed into the radios. I believe if the home repeater goes away the radios homed on that box do go numb/dead. 512 MHz and down to 136 or whatever will all be narrowband by 2013 anyway, except I haven't seen provisions for it for part 95 (GMRS) yet, so it will likely be exempt. Jim Barbour WD8CHL 6 years away in Land Mobile Radio is another lifetime... For the near term we're also watching to see if Analog TV goes away when they say it should. I'm betting it won't... cheers, s.
[Repeater-Builder] Re: subaudibe tones..
These days no reason not to use PL. Leaving a radio open is inviting intermod and all kinds of crap. PL keeps stuff nice and quiet. Never did understand why people put up repeaters without PL. And, no, Texas has a pretty good official coordinating body. But it was recently decided to require tone access. Or DCS. Didn't hear anybody in the room object. And its simple to establish a standard tone, like 100.0 (1Z) as the default. If there's one thing I can't stand is buzzing, belching intermod keying a radio. GeorgeC W2DB Awstin, TX --- In Repeater-Builder@yahoogroups.com, skipp025 [EMAIL PROTECTED] wrote: You mean to tell us there are so many repeaters on the air in Texas that even the low population rural area repeaters must operate constant ctcss? CTCSS operational control is a nice idea when there is a need. Otherwise it can and does turn people away quite fast. The saving grace is at least most newer radios have a built in ctcss encoder. Is your repeater coordination group run by a lot of wanna'be radio politician types? Do the coordination people in power seem to linger around and rarely change out of office? (ie the same group of people rotate through the same elected coordinator positions?) Is there a slight hint of a coordinated fishy smell in your area? :-) cheers, s. Any new repeater coordination in Texas MUST have CTCSS or DCS access, no exception. Only older coordinations are grandfathered with open squelch access. It just does not make any sense to put on a repeater these days without some kind of access control. Unfortunately, some hams equate access control to a 'closed' system. That kind of thinking needs to go the way of AM phone :- ) 73 - Jim W5ZIT
[Repeater-Builder] Re: ltr repeater system
Hi Mike, Nothing wrong with the way most Zetron Products work. My beef with Zetron is how they dropped all support after 5 years on some high end Zetron Products I have here. Then they tried to charge me $35 for another simple replacement owners manual and older software is most often no longer available. Otherwise their stuff is pretty straight- forward but tends to be a little harder to interface. It also tends to cost a lot more than other equivalent function controllers. The mentioned CSI-4200 is an easy install, programs easy and the data buss transfers all programming to the other paralleled controllers. No extras to buy like the validator requirement of the IDA units and it will talk standard LTR and Uniden LTR buss protocols. I talk to it using simple hypertermal and/or PC Plus type programs. Never had one fail ever... But if the Zetron Products work well for you... keep on with whatever you like best. cheers, s. Mike Mullarkey [EMAIL PROTECTED] wrote: Skipp, If I can add my two cents in, use the Zetron controllers and your project will be much easer and work. Not knocking the other controllers, im sure there are plenty of good controllers but I just have the most experience with the Zetron controllers. Mike
Re: [Repeater-Builder] Re: subaudibe tones..
Bob Dengler wrote: One concept that really helps in this area is CTCSS tone frequency standardization, IOW tones by region. All you then need to know is the freq. being used in the area you're traveling to. Many areas are already well established: 110.9 in Rochester NY, 107.2 in Niagara Falls San Diego, 131.8 in Santa Barbara, 127.3 in Springfield MA. Even if you don't know what tone is in use, all you have to do is find the tone of one system. After that you can find the others by kerchunking (with ID of course!) all the other pairs with that tone. Bob NO6B It seems to me that if you have all the repeaters in an area running the same CTCSS tone, and start fighting a mixing problem... everything is going to be back to keying everything else in short order. Out here, whether by design or by mistake -- I don't know which, it was all before my time -- the different large clubs all ended up using their own tones for their repeaters... Our club is 107.2, another large club is 103.5, the statewide linking system is 123.0, a couple of smaller clubs use 100.0... No one's the same, all require tone to access the repeater in almost all cases (there are a few die-hards with CSQ repeaters, but most have had to use controllers that have anti-kerchunk features to keep the noise/crud out), and not to many folks complained -- after the initial whining when most of the clubs moved together to require CTCSS, years ago. Nate WY0X
[Repeater-Builder] Re: Subaudible Tones (Was subaudibe tones..)
Before we embrace CDCSS as a cure-all, let us not forget that ALL standard CDCSS codes use the same 134.4 Hz turn-off tone for muting. That means that a mobile user keying distant repeater on the same frequency as yours, even if using a different CDCSS code, will mute your repeater at the same time. This is one of the nasty little secrets about CDCSS. Although few Amateur-grade portable and mobile radios provide reverse-burst squelch tail elimination at this time, it will probably become a standard feature before long. There is already a large number of Hams who use high-tier Motorola and Kenwood radios not only for the quality and durability, but also for the silent muting that results from reverse burst. The freedom from annoying squelch crashes is reason enough to use either CTCSS or CDCSS, in my opinion. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of MCH Sent: Tuesday, August 28, 2007 2:17 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: subaudibe tones.. Same in WPA... http://www.wprc.us/ctcss.htm http://www.wprc.us/ctcss.htm The recently adopted CDCSS codes are not on the map yet. SNIP
Re: [Repeater-Builder] Re: Subaudible Tones (Was subaudibe tones..)
Fortunately, all are still using FM, so capture effect will not allow the repeater to see the TOC of the other weak user. I have never - ever - heard a false mute of a signal from the TOC of 'other users'. Before that happens, the repeater will lose the CDCSS code and will mute due to loss of code rahter than see a TOC. And even when that happens, the signal will come right back when it can see the valid CDCSS code. Aside from the above, what is the difference of what you described vs a repeater using CTCSS seeing the TOC as another CTCSS tone? It seems that should happen too if it can happen at all. Joe M. Eric Lemmon wrote: Before we embrace CDCSS as a cure-all, let us not forget that ALL standard CDCSS codes use the same 134.4 Hz turn-off tone for muting. That means that a mobile user keying distant repeater on the same frequency as yours, even if using a different CDCSS code, will mute your repeater at the same time. This is one of the nasty little secrets about CDCSS.
Re: [Repeater-Builder] Re: subaudibe tones..
Nate Duehr wrote: It seems to me that if you have all the repeaters in an area running the same CTCSS tone, and start fighting a mixing problem... everything is going to be back to keying everything else in short order. That's the beauty of it. You will be dealing only with ham repeaters and can easily solve any issues. By using any tone, you will be dealing with PS vs ham and we all know who will win out in that case. By limiting the number of tones, the two-way shops can avoid that tone in that area if they want to avoid issues with ham transmitters. Most of the two-way shops will gladly agree since they know what some of the ham equipment is like cough spectrum cough. As one who has 90% of the ham repeaters running the same tone, and few if any problems, I don't see your argument. Joe M.
RE: [Repeater-Builder] Re: Subaudible Tones (Was subaudibe tones..)
Joe, The fact that you have never, ever heard of this problem is interesting, because it is very common. In fact, the County of Santa Barbara had to make some major changes in their vast radio system to preclude the problems I mentioned. The most common situation resulting in the unwanted turn-off code action is when a mobile in the coverage area of Repeater A is talking through distant Repeater B, while a portable (or weaker mobile) is using repeater A. Each time the mobile transmits, it captures Repeater A- blocking the portable- and then mutes Repeater A when it unkeys. Needless to say, this can be very frustrating to the portable user, especially when he cannot hear any voice from the other station. The same radio system also had a problem at one of the really dense sites, where every channel on both VHF and UHF used the same CTCSS tone, because the County made it their standard. Due to various mixing and intermod products, many repeaters were being keyed without any valid input. Once the various repeaters were given different PL tones, the problems went away. As you pointed out, PL tones that are close to 134.4 Hz can cause inadvertent turnoff of CDCSS-equipped receivers. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of MCH Sent: Tuesday, August 28, 2007 6:58 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Subaudible Tones (Was subaudibe tones..) Fortunately, all are still using FM, so capture effect will not allow the repeater to see the TOC of the other weak user. I have never - ever - heard a false mute of a signal from the TOC of 'other users'. Before that happens, the repeater will lose the CDCSS code and will mute due to loss of code rahter than see a TOC. And even when that happens, the signal will come right back when it can see the valid CDCSS code. Aside from the above, what is the difference of what you described vs a repeater using CTCSS seeing the TOC as another CTCSS tone? It seems that should happen too if it can happen at all. Joe M. Eric Lemmon wrote: Before we embrace CDCSS as a cure-all, let us not forget that ALL standard CDCSS codes use the same 134.4 Hz turn-off tone for muting. That means that a mobile user keying distant repeater on the same frequency as yours, even if using a different CDCSS code, will mute your repeater at the same time. This is one of the nasty little secrets about CDCSS.
RE: [Repeater-Builder] Duplexers
At 8/27/2007 20:52, you wrote: Yes your right VSWR is the ratio between Vmax and Vmin, node and anodes, of the interference pattern caused by standing waves. Even still there is a point where the voltage is at a minimum on the line. What happens if that point is at the transmitters output... does it help keep the heat down in the transmitter due to high SWR? It doesn t matter where the min and max are on the line. The same amount of reflected power will be seen at any point. Reflected power does NOT get back into the transmitter. It gets re-reflected back towards the antenna when it reaches the transmitter circuits. I don't buy into this. In order for reflected power to not be absorbed by the TX, it would have to appear totally reactive. Although I've never measured one, I don't believe that's the case. If you have two watt meters and an antenna matching device you can put one wattmeter between the transmitter and the matching device and tune it for minimum reflected power on the first meter. Then with a second meter between the tuner and the mismatched load you can see the second wattmeter that is reading the reflected power. The second wattmeter will have a higher forward power reading than the first due to the added re-reflected power. This doesn't sound right either, as there should be no reflected power at the antenna if it's been matched further down the line. The tuner would be adjusted so as to create a conjugate impedance of the antenna at the end of the feeding coax, thus eliminating the mismatch. My guess is that the higher power reading on the wattmeter is due to the weird impedances it's seeing on both its input output. Bob NO6B
Re: [Repeater-Builder] Re: Subaudible Tones (Was subaudibe tones..)
Threaded... Eric Lemmon wrote: Joe, The fact that you have never, ever heard of this problem is interesting, because it is very common. In fact, the County of Santa Barbara had to make some major changes in their vast radio system to preclude the problems I mentioned. The most common situation resulting in the unwanted turn-off code action is when a mobile in the coverage area of Repeater A is talking through distant Repeater B, while a portable (or weaker mobile) is using repeater A. Each time the mobile transmits, it captures Repeater A- blocking the portable- and then mutes Repeater A when it unkeys. That's capture effect if I'm understanding what you are saying. If so, it has nothing to do with any CTCSS/CDCSS used (or not used). Even if it mutes repeater A, that repeater should immediately unmute when it sees the valid code from the portable after the mobile unkeys. If not, it is a controller problem. Needless to say, this can be very frustrating to the portable user, especially when he cannot hear any voice from the other station. Yes it would. I've heard capture effect, too, as well as repeater blocking (which happens when a strong signal has capture effect over another user). Of course it results in muting of the repeater and the inability to use it unless you can crank out a signal strong enough to capture the signal that is capturing yours, but again, this has nothing to do with CTCSS/CDCSS other than it would appear the repeater is 'down'. The same radio system also had a problem at one of the really dense sites, where every channel on both VHF and UHF used the same CTCSS tone, because the County made it their standard. Due to various mixing and intermod products, many repeaters were being keyed without any valid input. Sounds like poor RF management or poor TX/site design. Once the various repeaters were given different PL tones, the problems went away. I bet it didn't go away. Changing the tones simply masked the problem the same as adding CTCSS to a repeater receiver will not let you HEAR a signal on the input. But the interfering signal is still there causing interference to any users. It is a proven myth that CTCSS/CDCSS will eliminate interference. As you pointed out, PL tones that are close to 134.4 Hz can cause inadvertent turnoff of CDCSS-equipped receivers. 73, Eric Lemmon WB6FLY That's not what I said. I said the TOC would be interpreted as an 'invalid' CTCSS tone on a repeater that uses... say 162.2 Hz. But, what causes the muting is capture effect of the signal which results in the inability of the decoder to see the valid CTCSS/CDCSS through the stronger signal with a different CTCSS/CDCSS or even no CTCSS/CDCSS. It has nothing to do with any turn off codes. It has everything to do with capture effect. Joe M. -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of MCH Sent: Tuesday, August 28, 2007 6:58 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Subaudible Tones (Was subaudibe tones..) Fortunately, all are still using FM, so capture effect will not allow the repeater to see the TOC of the other weak user. I have never - ever - heard a false mute of a signal from the TOC of 'other users'. Before that happens, the repeater will lose the CDCSS code and will mute due to loss of code rahter than see a TOC. And even when that happens, the signal will come right back when it can see the valid CDCSS code. Aside from the above, what is the difference of what you described vs a repeater using CTCSS seeing the TOC as another CTCSS tone? It seems that should happen too if it can happen at all. Joe M.
Re: [Repeater-Builder] Re: subaudible tones..
At 8/28/2007 15:37, you wrote: The Network RC Parts are most often the biggest sinner. Cheap caps and resistors keep the show moving along even if you don't want to travel that road. cheers Bob, s. Way back when I used tantalum capacitors, which I was told were the most stable; the Rs didn't seem to matter so long as they weren't the dark brown cylindrical ones (I suspect they're unsealed, as we have a bunch at work that have changed by one whole standard resistance value just by sitting in the bins for 30+ years). Since then I've discovered polystyrene silver mica. Only problem is the required C values for subaudible tones are a bit above the max. values for those caps. ps: when we get done talking about the 555 ctcss encoder I've got a less popular 567 ctcss encoder/decoder circuit available. Never used a 567 for encoding, but one of my first repeater controllers used them for decoding column 0 tones (147* column tone shifted down). That worked until someone recorded us on the input played the tones back :( No, my favorite was the SSI-202. Not too expensive trouble-free decoding. Bob NO6B
Re: [Repeater-Builder] Re: ltr repeater system
Try to buy a Trident Raider book... $35 hardly buys the postage... Also, home channel needs to be FB8 if at all possible. Steve, want to buy some more Uniden ESAS switches? We have four sites of six channels each! thp skipp025 wrote: Hi Mike, Nothing wrong with the way most Zetron Products work. My beef with Zetron is how they dropped all support after 5 years on some high end Zetron Products I have here. Then they tried to charge me $35 f No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.484 / Virus Database: 269.12.10/977 - Release Date: 8/28/2007 4:29 PM
Re: [Repeater-Builder] Re: subaudibe tones..
At 8/28/2007 16:01, you wrote: Bob Dengler wrote: One concept that really helps in this area is CTCSS tone frequency standardization, IOW tones by region. All you then need to know is the freq. being used in the area you're traveling to. Many areas are already well established: 110.9 in Rochester NY, 107.2 in Niagara Falls San Diego, 131.8 in Santa Barbara, 127.3 in Springfield MA. Even if you don't know what tone is in use, all you have to do is find the tone of one system. After that you can find the others by kerchunking (with ID of course!) all the other pairs with that tone. Bob NO6B It seems to me that if you have all the repeaters in an area running the same CTCSS tone, and start fighting a mixing problem... everything is going to be back to keying everything else in short order. This gets us back to the CTCSS-bandaid issue. If your ham TXs are IMDing with each other landing back on your inputs, you need to fix it. The only IMD problems I've had linger on my systems were caused by non-amateur TXs. If amateur TXs were involved, we found the actual source of the problem fixed it. Bob NO6B
