Re: [Repeater-Builder] Re: MTR2000 Backplane Fuse
Thanks everyone, that was the info I needed. I had looked through the book several times, but didn't expect to find a section on fuse replacement in with 'modules'. Mouser has them in stock for $0.67 each Littlelfuse part number is 0453005.MR Thanks again Chuck wb6fly wrote: I took a close look at a spare Motorola MTR2000 fuse, part number 6583049X16, and can provide some additional data: The fuse is rectangular, with a square cross-section, and measures about 6.0mm by 2.6mm. It has a ceramic body, with silver-plated end caps. The legend IE5A is printed on one face. This fuse seems to be identical to Littelfuse (note the spelling) Series 453 Nano fuses. The data sheet is here: www.littelfuse.com/data/en/Data_Sheets/Littelfuse_Fuse_451_453.pdf 73, Eric Lemmon WB6FLY --- In Repeater-Builder@yahoogroups.com, Ray Brown kb0...@... wrote: - Original Message - From: Chuck Kimball n0...@... To: Repeater-Builder@yahoogroups.com Sent: Sunday, December 28, 2008 5:45 AM Subject: [Repeater-Builder] MTR2000 Backplane Fuse Good Day Everyone: I'm looking for some info on the small fuses on the backplane of the MTR2000 repeaters. I've got a Instruction/Field Service Manual 68P81096E30-C, and can't find anything in there on the part number for the fuse. Apparently Motorola doesn't think those are field replaceable. ;) They are a 5A very small 1/8x1/8x1/4* fuse not much larger than a surface mount resistor - looks to be ceramic with metal ends. I've seen these once before, but don't know the name of that style to do any sort of a search on it. LittleFuse. I forget their exact part designation but several models of hospital beds uses them. I had never seen them before and unfortunately got them from the mfgr. of the beds because I needed some overnight and didn't have time to search. I got about 10 of each (they range from 0.5 to 7 amps @ 32 VDC) plus fuse holders for each one for $200. (sigh) I can't give any of the fuses away, but if anyone wants any surface- mounts for these fuses, I think I have about 30 of them that I could give away. :-) Anyway, Newark stocks them, too. :-) Ray, KBØSTN Yahoo! Groups Links
[Repeater-Builder] cabinets available
a while back someone was looking for 6 ft cabinets outdoor a friend of mine mentioned to me today that he has several outdoor cabinets from paging stations. in the interest of passing valuable information along to them what wants it - - - CONTACT-- JIM PRACKER COMMUNICATIONS LEASING NOVELTY OH (20 MI E OF CLEVELAND BROWNS) 440-338-8121 LEAVE SHORT MESSAGE IF HE'S OUT YOU CAN MENTION THAT I REFERRED YOU , BUT IT'LL DO ME NO GOOD. HAPPY NEW YEAR TO ALL. Ted Bleiman K9MDM MDM Radio If its in stock...we've got it!
[Repeater-Builder] High capacity capacitors
Hello Group A little off subject but I am in need of sourcing high capacity capacitors ( 70 to 100 K uF - 35 v stuff ) New or Surplus are OK Any suggetions ? looking for good prices ( that is the limiting factor ! ) Ed Com/Rad Inc Recent Activity a.. 7New Members Visit Your Group Drive Traffic Sponsored Search can help increase your site traffic. Yahoo! Groups Do More For Cats Group Connect and share with cat owners like you Yahoo! Groups Join people over 40 who are finding ways to stay in shape. . -- No virus found in this incoming message. Checked by AVG - http://www.avg.com Version: 8.0.176 / Virus Database: 270.10.1/1868 - Release Date: 12/29/2008 10:48 AM
[Repeater-Builder] VHF Unified Chassis Micor
From retired parts, I am attempting to assemble a VHF Micor Unified chassis into a repeater. I already succesfully assembled the UHF model. I can not under any circumstances get any local speaker audio from the VHF chassis. The receiver is working and producing discriminator noise, measured at receiver pins 15 and 16.and on meter position 5. The audio squelch board works in another station. The audio pass board is good.(tried 2 other working parts from mobiles) Jumpers 1, 4, and 5 on the TLN 5644 backplane are in. J5-14 is jumpered to J5-19 On the backplane board, where the 30 receiver interconnect board pins come through, pin 6 to 14 in jumpered. J2 19 is jumpered to 20 What say you? Thanks, Terry
Re: [Repeater-Builder] VHF Unified Chassis Micor
Find the two speaker pins on the audio output module and with the module removed, check for continuity across the speaker leads. If you check from the output module end, you will hear the ohm meter put enough current through the speaker to hear a scratch in the speaker each time you connect the leads. An older analog meter will work a lot better for this test, as the R X 1 scale puts considerable current out through the leads. Checking this way will not only test the speaker but will also test the harness and any switching in the circuit. I had a problem with a GE speaker that I finally tracked to a blown fuse inside the speaker module that was not even on the schematic. 73 - Jim W5ZIT --- On Mon, 12/29/08, Terry wx3m.te...@gmail.com wrote: From: Terry wx3m.te...@gmail.com Subject: [Repeater-Builder] VHF Unified Chassis Micor To: Repeater-Builder@yahoogroups.com Date: Monday, December 29, 2008, 3:22 PM From retired parts, I am attempting to assemble a VHF Micor Unified chassis into a repeater. I already succesfully assembled the UHF model. I can not under any circumstances get any local speaker audio from the VHF chassis. The receiver is working and producing discriminator noise, measured at receiver pins 15 and 16.and on meter position 5. The audio squelch board works in another station. The audio pass board is good.(tried 2 other working parts from mobiles) Jumpers 1, 4, and 5 on the TLN 5644 backplane are in. J5-14 is jumpered to J5-19 On the backplane board, where the 30 receiver interconnect board pins come through, pin 6 to 14 in jumpered. J2 19 is jumpered to 20 What say you? Thanks, Terry _._,___
[Repeater-Builder] An intermod problem
Hey guys, Alright, need some advice on this one. I have a uhf, and a little big from what we can tell has been in the receiver for a long time. The output of my machine is 449.225 with an input of 444.225. We're running a wacom wp678 duplexer, which is tuned up just fine. One problem, right next to my repeater is the evil paging transmitter outputting on 152.6. As soon as it keys up, with a weak signal on my receiver, it totally desenses it. I can have a signal that is dfq with no paging transmitter, but as soon as it keys up, it is weak. Any ideas for getting rid of this? The third harmonic of the paging transmitter is 457.8. Thoughts? Thanks, Jed
Re: [Repeater-Builder] An intermod problem
The desense is probably caused by broadband noise at the paging transmitter's third harmonic. A notch cavity on the output of the paging transmitter might be the lowest-loss, most cost-effective remedy. Time to find out if you're a diplomat! 73, Paul, AE4KR - Original Message - From: Jed Barton To: Repeater-Builder@yahoogroups.com Sent: Monday, December 29, 2008 4:59 PM Subject: [Repeater-Builder] An intermod problem Hey guys, Alright, need some advice on this one. I have a uhf, and a little big from what we can tell has been in the receiver for a long time. The output of my machine is 449.225 with an input of 444.225. We're running a wacom wp678 duplexer, which is tuned up just fine. One problem, right next to my repeater is the evil paging transmitter outputting on 152.6. As soon as it keys up, with a weak signal on my receiver, it totally desenses it. I can have a signal that is dfq with no paging transmitter, but as soon as it keys up, it is weak. Any ideas for getting rid of this? The third harmonic of the paging transmitter is 457.8. Thoughts? Thanks, Jed
Re: [Repeater-Builder] VHF Unified Chassis Micor
Service manual and o-scope for signal tracing Milt N3LTQ - Original Message - From: Terry wx3m.te...@gmail.com To: Repeater-Builder@yahoogroups.com Sent: Monday, December 29, 2008 4:22 PM Subject: [Repeater-Builder] VHF Unified Chassis Micor From retired parts, I am attempting to assemble a VHF Micor Unified chassis into a repeater. I already succesfully assembled the UHF model. I can not under any circumstances get any local speaker audio from the VHF chassis. The receiver is working and producing discriminator noise, measured at receiver pins 15 and 16.and on meter position 5. The audio squelch board works in another station. The audio pass board is good.(tried 2 other working parts from mobiles) Jumpers 1, 4, and 5 on the TLN 5644 backplane are in. J5-14 is jumpered to J5-19 On the backplane board, where the 30 receiver interconnect board pins come through, pin 6 to 14 in jumpered. J2 19 is jumpered to 20 What say you? Thanks, Terry Yahoo! Groups Links
[Repeater-Builder] OT Battery Sale
Well I know a lot of us bought battery operated Equipment including Toys for kids and Grandkids, I had a Friend Tell Me about a great Battery sell at Radio Shack until 3 Jan 09 40 AA Or 40 AAA $9.99 this is their better batteries Enercell Alkaline PS You will never know how important this is until Christmas Morning when a child opens a Gift with a big smile But Santa forgot the batteries. http://tinyurl.com/79nxst Happy Holidays Don KA9QJG
Re: [Repeater-Builder] Re: OT: Radios and Coms in TV and Movies
Doug Dickinson wrote: The Orange Box and the Apcor (both Motorola) Hi Doug, You forgot about the other Orange Box made by Biocom (if I remember correctly). It had GE portables as it's guts Don't you wish you were back in Florida now, 80F and bright sun. Happy holidays to you and all the R-B members John -- John Mc Hugh, K4AG Coordinator for Amateur Radio National Hurricane Center, WX4NHC Home page:- http://www.wx4nhc.org
RE: [Repeater-Builder] Re: Astron P/S question
Laryn, If the power supply were a switching design, current foldback would occur. But, in the typical Astron RS-series linear supply, the firing of the SCR puts a bolted short on the output. As soon as the large capacitors on the output start to lose their charge, the regulator tries to maintain the output voltage by turning on the pass transistors to full conduction, quickly exceeding the current ratings of the transformer and rectifier diodes and blowing the fuse. Every time this has happened to an Astron RS supply (that I have personal knowledge of), it has blown the fuse. Every time. Odd that your experience is different. Because of their (RS-series) relative instability in high-RF environments, I now install only Duracomm, Samlex, and Astron switching power supplies. Lightweight, very efficient, and very reliable. Nuff said. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Laryn Lohman Sent: Tuesday, December 23, 2008 9:33 AM To: Repeater-Builder@yahoogroups.com Subject: [Repeater-Builder] Re: Astron P/S question --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , Bob M. msf5kg...@... wrote: Whether it's the SCR itself, or the sense circuit driving it, something is causing it to fire and blow the fuse. You'd need to measure the actual output voltage of the supply to see if it's going that high or if the SCR is being falsely triggered. Of course, you only get one shot at trying it before the fuse blows. Why is the fuse blowing? Shouldn't the crowbar firing cause simple current foldback? All of my Astrons do, and never blow fuses. My apoligies if this has been brought up before... Laryn K8TVZ
RE: [Repeater-Builder] Re: Astron P/S question
I should point out that Astron has made several significant changes to the RS-series regulator boards over the past 20 years, and that may explain why some Astron power supplies always blow the input fuse when shorted, while others never do. Every one of my own Astron linear power supplies is more than twenty years old, and all of them blow the input fuse when shorted by the SCR. Obviously, some posters report differing results, and that may be due to recent changes in the regulator board's design. For what it's worth, almost every Astron regulator board I've seen has a few extra resistors or capacitors added to it, as if each one was customized during manufacture. According to Fred, Astron's lead technician, some components are still being changed to make the units more stable- decades after the original design! Here's one tip I learned a long time ago: Use exactly the fuse type and rating that Astron specifies for the specific power supply. Don't substitute a slow-blow fuse for a fast-blow, and don't use a higher-rated fuse or one that is intended for automotive use in place of one rated for 250 volts. If the correct fuse keeps blowing, there is a problem that should be found and fixed. Most Astron power supplies include an MOV (Metal Oxide Varistor) immediately downstream of the fuse. Such devices are usually rated for 130 VAC when applied on devices that operate at 120 VAC. If the line voltage is abnormally high, the MOV will get warm and become more likely to enter avalanche mode on modest spikes. Utilities are supposed to maintain the nominal utilization voltage at 120 VAC +/- 5%, so if the voltage ever exceeds 126 VAC, or falls below 114 VAC, it's time to complain to the electrical provider. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Adam T. Cately Sent: Friday, December 26, 2008 6:14 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Astron P/S question At 07:38 AM 12/26/08 -0500, you wrote: That pretty much confirms my thinking. If the supply is blowing fuses, something is actually wrong. The crowbar shouldn't cause it to happen. Well... Yes and no... If the SCR fires, you dump all the available current through the supply to ground, and the supply will blow the fuse - THAT is the designed re- sponse so that you don't let it sit there and burn up. When you short the output - IF the current-sense circuitry is working to spec, the supply sees the rise in current and shuts down the voltage to alleviate the SCR from firing - again, THAT is what this circuit was designed for. I always *assumed* the SCR was for over-voltage (shorted output pass transistor) and the fold-back was for over-current, under regular output conditions. If the supply blows the fuse, something IS wrong, but it IS DESIGNED to do that when something is wrong, so... Chuck WB2EDV - Original Message - From: william...@aol.com mailto:william474%40aol.com To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Sent: Thursday, December 25, 2008 11:41 PM Subject: Re: [Repeater-Builder] Re: Astron P/S question I have an Astron RM-35M (35Amp) that I just tested by shorting the output and it doesn't blow the fuse. I think I would be looking for something in the primary circuit that might be shorting like the transformer primary or the surge arrestor or maybe the wiring. I have seen transformers that short after they warm up a little. Bill - WA0CBW In a message dated 12/25/2008 10:11:11 P.M. Central Standard Time, lar...@hotmail.com mailto:larynl%40hotmail.com writes: --- In Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com , Chuck Kelsey wb2...@... wrote: I have an old Bullet power supply built from a kit (anyone remember those?) that uses the 723. You can short the output time and time again and it simply folds back. heheheh I have one of those still in service on a repeater. Re-capped it a year ago and it still works fine. As I recall a shorted output simply folds back, like you say. I also have two Astrons here on the bench. One is a VS12, the other is a RS12. When the output is directly shorted with heavy wire they both simply fold back. Shorted them dozens of times; never a blown fuse. Laryn K8TVZ Yahoo! Groups Links -- Don't be the last to know - click here for the latest news that will have people talking. !DOCTYPE HTML PUBLIC -//W3C//DTD HTML 4.0 Transitional//EN HTMLHEAD META http-equiv=Content-Type content=text/html; charset=iso-8859-1 META content=MSHTML 6.00.6000.16788 name=GENERATOR STYLE/STYLE /HEAD BODY id=role_body style=FONT-SIZE: 10pt; COLOR: #00; FONT-FAMILY: Arial bottomMargin=7 bgColor=#ff leftMargin=7 topMargin=7 rightMargin=7 DIVThat pretty much
[Repeater-Builder] Reed vs. Reedless Boards in Mitrek Radios
I recently acquired a Kenwood HM-250 Audio Distortion Analyzer, and I have been experimenting with various CTCSS tone encoders to find which produce the purest tones. Since I am putting together a 6m repeater using Mitrek radios, I wanted to compare the older HLN4020B reed board to the newer HLN4181A reedless board. What an eye-opener! At the outset, my gut feeling was that the reed board would produce a purer tone than the digital reedless board, since the reeds are essentially tuning forks. That turned out to be a false assumption. With two known-good tone boards hooked up on the bench, the 4020B reed board consistently produced a 127.3 Hz tone with distortion ranging from 0.75% to 1.52%, while the 4181A reedless board produced the same tone with only 0.43% distortion. I adjusted the output level pot (R23) on the 4181A board to match the output level of the 4020B board. I tested the 4020B board with six 127.3 Hz reeds. Another interesting fact emerged from my experiment: Although the PL tone reeds can be plugged into their sockets in either of two positions, I found that there was definitely a difference in the amount of distortion produced. The differences ranged from 0.1% up to 0.6%- not much, but surprising, since the reeds are supposedly symmetrical. I got similar results with KLN6209A, KLN6210A, and TLN6824A reeds. For comparison, I measured the distortion at 127.3 Hz from several pieces of test equipment, with the following results: HP 204B Audio Generator: 0.24% Motorola R2600D Service Monitor: 0.26% Wavetek 188 Audio Generator: 0.19% CSI TE-64D Tone Generator: 0.76% My next step is to evaluate the purity of the CTCSS tones after passing through an RF link. Some radios- cheap ones especially- use rather coarse tone synthesis techniques to generate PL tones, and the resulting tones are prone to falsing and talk-off problems. Stay tuned... 73, Eric Lemmon WB6FLY
RE: [Repeater-Builder] MTR2000 Backplane Fuse
I took a close look at a spare Motorola MTR2000 fuse, part number 6583049X16, and can provide some additional data: The fuse is rectangular, with a square cross-section, and measures about 6.0mm by 2.6mm. It has a ceramic body, with silver-plated end caps. The legend IE5A is printed on one face. This fuse seems to be identical to Littelfuse (note the spelling) Series 453 Nano fuses. The data sheet is here: www.littelfuse.com/data/en/Data_Sheets/Littelfuse_Fuse_451_453.pdf 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of Ray Brown Sent: Sunday, December 28, 2008 10:01 AM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] MTR2000 Backplane Fuse - Original Message - From: Chuck Kimball n0...@yahoo.com mailto:n0nhj%40yahoo.com To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Sent: Sunday, December 28, 2008 5:45 AM Subject: [Repeater-Builder] MTR2000 Backplane Fuse Good Day Everyone: I'm looking for some info on the small fuses on the backplane of the MTR2000 repeaters. I've got a Instruction/Field Service Manual 68P81096E30-C, and can't find anything in there on the part number for the fuse. Apparently Motorola doesn't think those are field replaceable. ;) They are a 5A very small 1/8x1/8x1/4* fuse not much larger than a surface mount resistor - looks to be ceramic with metal ends. I've seen these once before, but don't know the name of that style to do any sort of a search on it. LittleFuse. I forget their exact part designation but several models of hospital beds uses them. I had never seen them before and unfortunately got them from the mfgr. of the beds because I needed some overnight and didn't have time to search. I got about 10 of each (they range from 0.5 to 7 amps @ 32 VDC) plus fuse holders for each one for $200. (sigh) I can't give any of the fuses away, but if anyone wants any surface- mounts for these fuses, I think I have about 30 of them that I could give away. :-) Anyway, Newark stocks them, too. :-) Ray, KBØSTN
[Repeater-Builder] Reed vs. Reedless PL Boards
I recently acquired a Kenwood HM-250 Audio Distortion Analyzer, and I have been experimenting with various CTCSS tone encoders to find which produce the purest tones. Since I am putting together a 6m repeater using Mitrek radios, I wanted to compare the older HLN4020B reed board to the newer HLN4181A reedless board. What an eye-opener! My gut feeling was that the reed board would produce a purer tone than the digital reedless board, since the reeds are essentially tuning forks. That turned out to be a false assumption. With two known-good tone boards hooked up on the bench, the 4020B reed board consistently produced a 127.3 Hz tone with distortion ranging from 0.75% to 1.52%, while the 4181A reedless board produced the same tone with only 0.43% distortion. I adjusted the output level pot (R23) on the 4181A board to match the output level of the 4020B board. I tested the 4020B board with six 127.3 Hz reeds. Another interesting fact emerged from my experiment: Although the PL tone reeds can be plugged into their sockets in either of two positions, I found that there was definitely a difference in the amount of distortion produced. The differences ranged from 0.1% up to 0.6%- not much, but surprising, since the reeds are supposedly symmetrical. I got similar results with KLN6209A, KLN6210A, and TLN6824A reeds. For comparison, I measured the distortion at 127.3 Hz from several pieces of test equipment, with the following results: HP 204B Audio Generator: 0.24% Motorola R2600D Service Monitor: 0.26% Wavetek 188 Audio Generator: 0.19% CSI TE-64D Tone Generator: 0.76% My next step is to evaluate the purity of the CTCSS tones after passing through an RF link. Some radios- cheap ones especially- use rather coarse tone synthesis techniques to generate PL tones, and the resulting tones are prone to falsing and talk-off problems. Stay tuned... 73, Eric Lemmon WB6FLY
[Repeater-Builder] Problem remote base linking of 2 repeaters using CAT 300 DXL controller
Fellow repeater builders, I am a relative novice at repeater linking and need some trouble shooting/system design advice. I have a 440 repeater with 3 two meter remote base radios tied together using the CAT 300 DXL controller with the RLS board. The remote base radios are tuned to local repeaters that we would like to link together. Individually, each remote base radio works fine meaning I can turn it on with via 440 repeater and qso on the target repeater. Also, another local repeater with a 440 remote base is able to link the 440 repeater and when I turn on one of the remote base radio and link in another 2 mtr repeater it works fine (repeater key up and down like one big repeater). The problem arises when I try to use the two or more 2 mtr remote base radios to link two 2 mtr repeaters together. The system comes up stays up - never unkeys. Is this a hang time issue? Or is there something wrong about trying to link two repeaters on two meters with 2 meter remote bases through a 440 machine - usually folks target the 440 repeater with a remote base not the other way around? Could it be a controller setting issue? I am really stuck at the moment and I appreciate any thoughts you may have. It sure would be nice to have these repeaters linked for our nets and is generally kinda cool if we can pull this off. Vexed in Virgina, Chris W4VX
[Repeater-Builder] Icom RP-1520 2m repeater
Does anybody on the list here have some good technical knowledge on the above repeater? I'm trying to get the CTCSS tone board working in one and can't seem to. I don't think its broke, but need someone to point me in the right direction on some troubleshooting. Thanks. 73, Brian
[Repeater-Builder] OT Digital TV Converter Coupons in Tight Supply Mon Dec 29, 2008
OT But for cheap people like Me I want the Free Coupons I dont need Cable , Dish Etc But I sure want to keep My Old Sony 57 In analoq TV Digital TV Converter Coupons in Tight Supply ,I Have No idea if this is true , I have not ordered Mine thinking the longer I wait the Better selection and prices , But I think after reading this I will order Mine more info at http://www.dtv.gov/ Don KA9QJG December 29, 2008 WASHINGTON -- U.S. consumers who wait too long to request government coupons to subsidize converter boxes for the digital television transition in February may come up empty-handed, a regulator has warned. Due to a last-minute rush of coupon requests, demand may exceed supply in the coming month, said the Department of Commerce official overseeing the subsidy program. Rep. Ed Markey, a Massachusetts Democrat who asked for the update on the digital TV transition, said Congress may need to quickly pass additional funds in early January for the coupons. Congress ordered the switch to digital signals, effective February 17, 2009, to free up public airwaves for other uses such as for police and fire departments. The switch will mean improved picture and sound for TV viewers, but about 15 percent of the population rely on analog-only over-the-air signals and therefore need a converter box to keep their screens from going black. The government program doling out $40 coupons to subsidize the converter boxes is likely to reach the $1.34-billion limit of its budgetary authority in the first week of January, said Meredith Attwell Baker, acting assistant secretary for Communications and Information at the National Telecommunications and Information Administration. Once the obligation ceiling is reached, the program will hold coupon requests until funds from unredeemed coupons become available, said Baker in the December 24 letter to Markey who chairs the House subcommittee on telecommunications and Internet matters. NTIA realizes that this would likely result in consumer confusion, she added. If the high demand continues at its current rate of more than 1.5 million requests per week, the agency could run out of coupons in late January. There are about 60 models of boxes to choose from, costing between $40 and $90, before the coupon, according to Consumers Union, which produces the magazine Consumer Reports. Markey said Baker's response was worrying. It is becoming increasingly clear that at minimum Congress may need to quickly pass additional funding for the converter box program in early January, he said in a statement.
Re: [Repeater-Builder] Reed vs. Reedless Boards in Mitrek Radios
With the reedless board chip being nothing more then a simple resister network, I wonder what your purity results might be if you built-up a 127.3 network using 1, 5,and 10% 1/8w resisters for comparison as well. -- Doug N3DAB/WPRX486/WPJL709 Eric Lemmon wb6...@verizon.net wrote: = I recently acquired a Kenwood HM-250 Audio Distortion Analyzer, and I have been experimenting with various CTCSS tone encoders to find which produce the purest tones. Since I am putting together a 6m repeater using Mitrek radios, I wanted to compare the older HLN4020B reed board to the newer HLN4181A reedless board. What an eye-opener! At the outset, my gut feeling was that the reed board would produce a purer tone than the digital reedless board, since the reeds are essentially tuning forks. That turned out to be a false assumption. With two known-good tone boards hooked up on the bench, the 4020B reed board consistently produced a 127.3 Hz tone with distortion ranging from 0.75% to 1.52%, while the 4181A reedless board produced the same tone with only 0.43% distortion. I adjusted the output level pot (R23) on the 4181A board to match the output level of the 4020B board. I tested the 4020B board with six 127.3 Hz reeds. Another interesting fact emerged from my experiment: Although the PL tone reeds can be plugged into their sockets in either of two positions, I found that there was definitely a difference in the amount of distortion produced. The differences ranged from 0.1% up to 0.6%- not much, but surprising, since the reeds are supposedly symmetrical. I got similar results with KLN6209A, KLN6210A, and TLN6824A reeds. For comparison, I measured the distortion at 127.3 Hz from several pieces of test equipment, with the following results: HP 204B Audio Generator: 0.24% Motorola R2600D Service Monitor: 0.26% Wavetek 188 Audio Generator: 0.19% CSI TE-64D Tone Generator: 0.76% My next step is to evaluate the purity of the CTCSS tones after passing through an RF link. Some radios- cheap ones especially- use rather coarse tone synthesis techniques to generate PL tones, and the resulting tones are prone to falsing and talk-off problems. Stay tuned... 73, Eric Lemmon WB6FLY
RE: [Repeater-Builder] Reed vs. Reedless Boards in Mitrek Radios
Doug, Since the resistor array in the TRN4224A serves only to program the digital synthesizer in the encoder/decoder chip, changing resistors should not make any difference in the tone purity. However, I once built up an array for testing using discrete resistors, and- if I can find it- I'll run a purity test on it. Mike Morris has a very informative article about the HLN4181A board here: www.repeater-builder.com/mitrek/mitrek-hln4181-info.html 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:repeater-buil...@yahoogroups.com] On Behalf Of rb_n3...@tds.net Sent: Monday, December 29, 2008 9:28 PM To: Repeater-Builder@yahoogroups.com Cc: Eric Lemmon Subject: Re: [Repeater-Builder] Reed vs. Reedless Boards in Mitrek Radios With the reedless board chip being nothing more than a simple resister network, I wonder what your purity results might be if you built-up a 127.3 network using 1, 5,and 10% 1/8w resistors for comparison as well. -- Doug N3DAB/WPRX486/WPJL709 Eric Lemmon wb6...@verizon.net mailto:wb6fly%40verizon.net wrote: = I recently acquired a Kenwood HM-250 Audio Distortion Analyzer, and I have been experimenting with various CTCSS tone encoders to find which produce the purest tones. Since I am putting together a 6m repeater using Mitrek radios, I wanted to compare the older HLN4020B reed board to the newer HLN4181A reedless board. What an eye-opener! At the outset, my gut feeling was that the reed board would produce a purer tone than the digital reedless board, since the reeds are essentially tuning forks. That turned out to be a false assumption. With two known-good tone boards hooked up on the bench, the 4020B reed board consistently produced a 127.3 Hz tone with distortion ranging from 0.75% to 1.52%, while the 4181A reedless board produced the same tone with only 0.43% distortion. I adjusted the output level pot (R23) on the 4181A board to match the output level of the 4020B board. I tested the 4020B board with six 127.3 Hz reeds. Another interesting fact emerged from my experiment: Although the PL tone reeds can be plugged into their sockets in either of two positions, I found that there was definitely a difference in the amount of distortion produced. The differences ranged from 0.1% up to 0.6%- not much, but surprising, since the reeds are supposedly symmetrical. I got similar results with KLN6209A, KLN6210A, and TLN6824A reeds. For comparison, I measured the distortion at 127.3 Hz from several pieces of test equipment, with the following results: HP 204B Audio Generator: 0.24% Motorola R2600D Service Monitor: 0.26% Wavetek 188 Audio Generator: 0.19% CSI TE-64D Tone Generator: 0.76% My next step is to evaluate the purity of the CTCSS tones after passing through an RF link. Some radios- cheap ones especially- use rather coarse tone synthesis techniques to generate PL tones, and the resulting tones are prone to falsing and talk-off problems. Stay tuned... 73, Eric Lemmon WB6FLY
