[Repeater-Builder] Re: Spectrum Repeater CW ID 'er Bipolar Prom
Tim, I've been reading the repeater builder and was wondering if you have the Bipolar Prom solved? I have a Spectrum VHF repeater and encountered the same problem with the ID'er you have. If it is the same chip number as mine (I'll look at the number tomorrow... 21?? I think) they are capable of programming 4 different ID strings before the Prom is totally used up. They only use a single bit at each address and cycle downward through the chip's addresses to store the ID data. You then just set your ID'er to read the correct bit. I managed to program an additional channel on the chip from the previous owner (BY HAND) and got mine going. I finally found and purchased a couple Prom chips... (don't recall where - been 5 yrs) If you let me know the number of the chip you need or number of the ID'er board I would be glad to share any info I might have. I could even let you have one of my chips if it will work for you. I never bothered to program either of my spares after sweating through blowing the original chip, one bit at a time. It ID's fine using the second channel and you know what they say... If it ain't broke --- Don't fix it !. I also didn't know anyone who owned a programmer and wasn't aware of the Repeater Group back then. As helpful as they are on here, if you ask, someone on this group must have a Bipolar Prom Burner kicking around that would program a chip if you provide the chip and data. Use my call at juno.com if you want to contact me off list. Larry - N7FM - Original Message - From: Mike Morris To: Repeater-Builder@yahoogroups.com Sent: Saturday, August 25, 2007 6:58 PM Subject: Re: [Repeater-Builder] Re: Spectrum Repeater CW ID 'er Bipolar Prom At 01:55 PM 08/24/07, you wrote: --- In Repeater-Builder@yahoogroups.com, skipp025 [EMAIL PROTECTED] wrote: Spectrum Repeater CW ID'er Bipolar Prom If the IDer has a PROM then little can and should be done to go another way...a new PROM. Spectrum sells a replacement prom from about $55, which is kind of out of line for a price... but at least it's available. You can find/ask someone with a bipolar prom burner to make a new chip for you. But you have to find the chip and figure out how to map your call sign into the new part. One can also replace a Prom with an Eprom using a small adapter daughterboard, which is a path I've used many times. You need only have the eprom, programmer and set up the programming. Prom daughter/adapter boards run under $20 each... Another option would be to disable the factory ID'er and install an ID-O-Matic or similar ID unit. cheers, skipp Thank you Skipp for the manual for the SCR-77. I can not contact Spectrum. They will not respond to there e-mails and when you call them you just getting a recording saying to leave a message, which I have, still no contact yet. I have also thought about installing another ID'er. What would be my best bet there. I have heard Com-Spec (Communication Specialists) makes a small simple ID'er. 73, Tim Or bypass the entire controller and use a low end NHRC or ICS controller to do it all.
[Repeater-Builder] Cleaning of Moto 1500 series dup.s
What are some of the methods that you folks have used in cleaning these cans...solvents, any anti-crud stuff afterward? Have any of you used Tarn-X and ACF-50 before? (http://www.corrosion-control.com/acf50.html) Just curious of results. Thanks, Robert
RE: [Repeater-Builder] Duplexers
Ya you should be able to trim your coax so the transmitter sees 50 ohms, which should be every 1/2 wave. All this does it protect the transmitter, the standing waves are still there, they just gets dissipated/radiated by the coax. No, no, no, no, no (thumping head on desk). If the VSWR on the line between the transmitter and the duplexer is anything other than 1:1, THERE DOES NOT EXIST a point along that line where the impedence is 50+j0. Line losses go up with VSWR, but coax doesn't radiate unless there are currents flowing on the shield, and those aren't a function of VSWR on the line. --- Jeff
RE: [Repeater-Builder] Duplexers
Jeff you have just made two statements that are the exect opposit of each other. If changing the length of cable makes a differance, then the swr as seen by the transmitter must change. Re-read what I said. Changing the cable length changes the *Z*, but it doesn't change the *VSWR*. As you vary the cable length, the Z changes in a cyclical fashion, but always remains at a constant VSWR. For any given VSWR, there are an infinite number of complex Z's that will produce that VSWR. As some transmitters can not be tuned for impedance mismatch, adding lengths of line may change the impedance where the transmitter will produce the maximan ammout of power out. Yes. But it doesn't change the VSWR. If say the duplexer is setup for a 50 ohm load and the transmitter wants to load into a 60 ohm load, then changing the length of cable between the duplexer and transmitter may let the transmitter see 60 ohms instead of 50 ohms. Not if the cables your using are also 50 ohms. If the duplexer presents a 50 ohms like you said, you can use whatever cable lengths you want and the resulting Z as seen by the transmitter will always be 50 ohms. Transmission lines only act as transformers when their characteristic Z is different than the termination Z. --- Jeff - Jeff DePolo - [EMAIL PROTECTED] Broadcast Sciences LLC, Valley Forge PA v: 610.917.3000 f: 610.917.3030
[Repeater-Builder] MSR 2000 UHF Band Splits
Hey all, Does anyone know the bandsplits for the UHF MSR 2000, or a web page that has a model no. reference chart? Thanks, Jesse
[Repeater-Builder] Re: Spectrum Repeater CW ID 'er Bipolar Prom
No problem Tim... also thank you to Lou for sending me/us another different copy of the manual so we pretty much have all versions covered. Hints Keywords when dealing with Spectrum: Call, leave your first name and phone number in a message saying that you want to order something and to please call back when they have a spare moment. (say nothing more about what item you want to order) When the guy calls you back say you want to order a CW ID'er prom for your repeater for an urgent project where the site access is very time limited by inbound weather (or some similar story). Order the prom with the firm instructions you need it asap (but not over-night shipping) and use your credit card for the purchase. Nicely beg/request for the part asap. If you receive nothing within the credit card charge dispute window... formally reverse the charge before the deadline. If the prom arrives in time... kiss the ground and bow to the east not to mention report back here with a few kind and real words and or your experience dealing with Spectrum. My last two dealings were actually quite good... just be semi firm that you need the prom asap and ask for a realistic estimate to actually receive your chip. Otherwise you should consider the ID-O-Matic (or similar) as a very cost effective replacement option. Hard to beat the $20 price tag... You need only disable the internal Spectrum CW ID unit, which is not that hard to do. Just the way Spectrum wants to do business... or lack there of. Decades ago I was offered a Spectrum Dealership... glad I didn't take it. But the original Demo Spectrum 440 repeater I have here is still on the air and working without any problems... ever. Stone stock and working well... go figure. cheers, skipp Thank you Skipp for the manual for the SCR-77. I can not contact Spectrum. They will not respond to there e-mails and when you call them you just getting a recording saying to leave a message, which I have, still no contact yet. I have also thought about installing another ID'er. What would be my best bet there. I have heard Com-Spec (Communication Specialists) makes a small simple ID'er. 73, Tim
[Repeater-Builder] Re: Spectrum - Bipolar Prom for CW ID 'er
With a modest cost higher than using a retrofit ID-O-Matic type replacement ID kit I like to lean in the direction of keeping the repeater original. See my just posted reply about dealing with spectrum. I would easily sell you the replacement prom but after moving to our new shop I/we don't yet have operational means to program it back on-line to burn it within a practical amount of time. Prom burning is not a big mover item. Try Spectrum first and get back to us with your results... then we'll help you along some path to get an ID'er back on line. In the future I hope to get the prom burner back on line or offer up the drop-in eprom replacement board option. cheers, skipp skipp025 at yahoo.com www.radiowrench.com [EMAIL PROTECTED] [EMAIL PROTECTED] wrote: That is the correct PROM. Mine is a 74287.But how do I program the prom?..Also, I don't need 25 of them.maybe 3. Thanks for the info...Now that I know where the PROM is in the CWID board and the part number maybe I can find someone to program it for me. THANKS! Tim
[Repeater-Builder] Re: Spectrum Repeater CW ID 'er Bipolar Prom
Or bypass the entire controller and use a low end NHRC or ICS controller to do it all. ... if replacing the original controller board operation with an external repeater controller would gain the some practical and/or functional abilities. Otherwise the ID-O-Matic CW ID'er is a pretty cool alternative that works very well. S.
[Repeater-Builder] CES 510SA Smart Patch MK3870 uP available
Guys, I hope its ok to post this here... I have for sale a small stock of NOS original factory ordered (way back then) MK3870 microprocessor chips for the CES 510SA Smart Patch. For more info please use this shortcut: http://miwww.com/click?127 Thanks. -Alex
[Repeater-Builder] Re: Duplexers
Jeff DePolo [EMAIL PROTECTED] wrote: Line losses go up with VSWR, but coax doesn't radiate unless there are currents flowing on the shield, and those aren't a function of VSWR on the line. Wait a minute Jeff... what about that crappy low cost silver jacket Super-flex Columbia branded coax I bought back in the 70's during the CB boom... Some of the cheaper coax brands have less than about 70% shielding making them pretty leaky to rf. It works just killer for adding a little extra signal horse-power to a carrier current broadcast station. Radiax without trying... :-) cheers, skipp
[Repeater-Builder] Re: MSR 2000 UHF Band Splits
Hi Jesse, A quick sum of the UHF MSR-2000 band splits normally described as three choices. A low range 403-430 model, the 450-483 MHz model and the T-Band high range 483-512 range. the 483 value might be a plus or minus a bit but those two ranges work toward those values. You will not get the T-Band range receiver to come down (unless you have a lot of time and skill... nor will you get the 415 MHz receiver up to 445 MHz without much serious effort. Better to trade and/or find replacement receivers. The out of range PA's should be operated at much reduced values and or modified... which includes work in the harmonic filter section. cheers, skipp Jesse Lloyd [EMAIL PROTECTED] wrote: Hey all, Does anyone know the band-splits for the UHF MSR 2000, or a web page that has a model no. reference chart? Thanks, Jesse
RE: [Repeater-Builder] Re: Duplexers
Wait a minute Jeff... what about that crappy low cost silver jacket Super-flex Columbia branded coax I bought back in the 70's during the CB boom... Coax leakage is different than currents flowing on the shield though... I remember having some RG8 from Radio Shack with braid openings that you could probably fit a pencil through. Some of the cheaper coax brands have less than about 70% shielding making them pretty leaky to rf. It works just killer for adding a little extra signal horse-power to a carrier current broadcast station. Radiax without trying... You could run it up the tower and have a really long antenna. Lots of capture area ;-)
Re: [Repeater-Builder] Re: Duplexers
Braided coax does radiate a little, there is no such thing as 100% braid. Thats why in the cable TV industry they have to use double braided coax in the headend, otherwise you can have a hell of a mess of stray RF in there. Coax loss is due to I^2R losses and radiation (and connector loss but thats not really part of the cable). On 8/26/07, skipp025 [EMAIL PROTECTED] wrote: Jeff DePolo [EMAIL PROTECTED] wrote: Line losses go up with VSWR, but coax doesn't radiate unless there are currents flowing on the shield, and those aren't a function of VSWR on the line. Wait a minute Jeff... what about that crappy low cost silver jacket Super-flex Columbia branded coax I bought back in the 70's during the CB boom... Some of the cheaper coax brands have less than about 70% shielding making them pretty leaky to rf. It works just killer for adding a little extra signal horse-power to a carrier current broadcast station. Radiax without trying... :-) cheers, skipp
Re: [Repeater-Builder] Re: MSR 2000 UHF Band Splits
I'm looking at a repeater with the model no of C7465B3106. Any Idea which split that would be? On 8/26/07, skipp025 [EMAIL PROTECTED] wrote: Hi Jesse, A quick sum of the UHF MSR-2000 band splits normally described as three choices. A low range 403-430 model, the 450-483 MHz model and the T-Band high range 483-512 range. the 483 value might be a plus or minus a bit but those two ranges work toward those values. You will not get the T-Band range receiver to come down (unless you have a lot of time and skill... nor will you get the 415 MHz receiver up to 445 MHz without much serious effort. Better to trade and/or find replacement receivers. The out of range PA's should be operated at much reduced values and or modified... which includes work in the harmonic filter section. cheers, skipp Jesse Lloyd [EMAIL PROTECTED] wrote: Hey all, Does anyone know the band-splits for the UHF MSR 2000, or a web page that has a model no. reference chart? Thanks, Jesse
[Repeater-Builder] An Icom 224MHz Repeater Receiver retrofit using a Hamtronics Receiver
An Icom 224MHz Repeater Receiver retrofit repair project using a replacement Hamtronics R302-6 Receiver. August 2007 One of our local groups has an Icom 224 MHz Amateur Repeater in service. After a number of years of reliable operation the repeater went off the air. The problem was traced to a dead receiver with a failed VCO Section, which of course requires replacement parts no longer available. Used working Icom Repeater Receivers are not often found on the surplus market or the popular online auction sites (Ebay). The repeater required an original replacement receiver board or equivalent similar function unit. Since the original is no longer available I decided to go the equivalent similar function replacement receiver route. Availability: There is a relatively small number of Replacement 222 MHz Repeater Receivers available for the Amateur Radio Market. The basic choices include Hamtronics, Maggiore, Spectrum and some of the surplus commercial radio conversions as found at the Repeater-Builder Web Site. Each of the mentioned choices has a number of Pro and Con Reasons used to make a purchase decision. Other viable manufactures making 224 MHz repeater receivers may be available and I just don't know about them yet. Selection: For this repair I chose a new Hamtronics R302-6 Repeater Receiver based on the product availability, my previous experience with Hamtronics Products, function and the synthesized frequency feature (no crystal order/wait time). The receiver arrived three days after my order already aligned and programmed on my repeater input frequency. I have a pretty large number of older Hamtronics Receiver and Transmitter Products and I will say this latest generation receiver is very well done. Hamtronics does not offer the R302-x series receiver products as a kit available with other earlier models. And for a change it's nice to have a receiver project arrive as a plug and play unit. Overview: After a quick review of the circuit diagram I was a bit concerned about the receiver front-end. One tuned circuit before the preamp transistor followed by two more stages at first glance doesn't look very hardy. I have a number of external receiver helical resonator front-end sections available, which I half expected to need when this receiver was placed on the air at the repeater site. It turns out after completing this project the installed R302-6 Receiver is quite the quality performer. Receiver blocking, preamp 3rd order intercept and 12dB Sinad testing values were all quite acceptable by modern commercial radio standards. Hamtronics has also revisited and improved the squelch hysterisis operation, the results being a less mushy or reduced dead-band value in the control knob rotation. In the past I've always modified (reduced) the squelch hysterisis values in Kit-Built Receivers based on my personal preference. Installation: The required wire lead connection points are board top mounted and well labeled. I wanted to remove the CTCSS (Sub-Tone) from the Repeat Audio source and provide an isolated COR Logic Output. I mounted the receiver in a modest aluminum box along with a Com Spec TS-32 CTCSS Decoder and a small DPDT Relay, which is ground-switched on by a 2N7000 FET. The receiver repeater audio output is routed through the onboard TS-32 Audio Filter Section before going to the External Repeater Controller. About 8 Volts DC is available on the Receiver Board COS/COR output pin when the squelch is opened, which is perfect to turn-on the 2N7000 relay driver circuit. A copy of that relay driver circuit is available in the Yahoo Midland Radio Group Files Section or upon request as a direct email from me. The two in-package dual-throw relay poles described above are available to provide isolated COR Function outputs to the external repeater controller. Solid-state switching is quite easily done but the added small relay offers a novel and quick method to source both active-low and active high COR Logic Outputs when connecting to the external repeater controller. CTCSS detection logic is also taken from the TS-32 board and made available on the added chassis rear panel D-9 (aka dB-9) connector. Small COR Relay failures have never been a problem in the normal life this or any type of similar equipment. Available Repeater Audio: Another nice addition to the current Hamtronics R302-6 Receiver is the clearly labeled squelched repeater audio and discriminator output connection points. The user now has the choice of the original classic terminated speaker method or squelched lower level audio connection points using the factory supplied solder posts. Sourcing the low level squelched repeat audio through a Com-Spec TS-32 on-board CTCSS filter allows independent adjustment of the local speaker volume level. The terminated speaker audio method used the local speaker audio as the repeat audio source meaning the volume control adjusted the audio level. Front panel mounted volume and squelch
[Repeater-Builder] Re: MSR 2000 UHF Band Splits
Maybe if I can get close to a UHF Manual on Monday... The simple check is to remove the receiver and transmitter cover and read the frequencies off the channel elements. Unless someone has removed the channel elements... skipp Jesse Lloyd [EMAIL PROTECTED] wrote: I'm looking at a repeater with the model no of C7465B3106. Any Idea which split that would be? On 8/26/07, skipp025 [EMAIL PROTECTED] wrote: Hi Jesse, A quick sum of the UHF MSR-2000 band splits normally described as three choices. A low range 403-430 model, the 450-483 MHz model and the T-Band high range 483-512 range. the 483 value might be a plus or minus a bit but those two ranges work toward those values. You will not get the T-Band range receiver to come down (unless you have a lot of time and skill... nor will you get the 415 MHz receiver up to 445 MHz without much serious effort. Better to trade and/or find replacement receivers. The out of range PA's should be operated at much reduced values and or modified... which includes work in the harmonic filter section. cheers, skipp Jesse Lloyd ve7lyd@ wrote: Hey all, Does anyone know the band-splits for the UHF MSR 2000, or a web page that has a model no. reference chart? Thanks, Jesse
Re: [Repeater-Builder] Re: MSR 2000 UHF Band Splits
Jesse, Look closer at that model number; MSR2000 UHF stations will normally be C74GRB-yy or C74GSB-yy. But, the station model number won't reveal the UHF band split. If your station has a TLE2283 PA deck, it is for 450-494 MHz; if it has a TLE2284 PA deck, it is for 494-512 MHz. 73, Eric Lemmon WB6FLY -Original Message- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Jesse Lloyd Sent: Sunday, August 26, 2007 11:12 AM To: Repeater-Builder@yahoogroups.com Subject: [Norton AntiSpam] Re: [Repeater-Builder] Re: MSR 2000 UHF Band Splits I'm looking at a repeater with the model no of C7465B3106. Any Idea which split that would be?
Re: Re: [Repeater-Builder] Re: Duplexers
Coax losses are mainly due to LC values. If just I^R then losses would be same for low and high frequencies. One finds little R in most coax although there are some and yes some losses due to it. The losses of parrallel lines with small wire are much less due to much less C between the conductors due to much less surface area between the conductors. 73, ron, n9ee/r From: Jesse Lloyd [EMAIL PROTECTED] Date: 2007/08/26 Sun PM 01:08:49 CDT To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Re: Duplexers Braided coax does radiate a little, there is no such thing as 100% braid. Thats why in the cable TV industry they have to use double braided coax in the headend, otherwise you can have a hell of a mess of stray RF in there. Coax loss is due to I^2R losses and radiation (and connector loss but thats not really part of the cable). On 8/26/07, skipp025 [EMAIL PROTECTED] wrote: Jeff DePolo [EMAIL PROTECTED] wrote: Line losses go up with VSWR, but coax doesn't radiate unless there are currents flowing on the shield, and those aren't a function of VSWR on the line. Wait a minute Jeff... what about that crappy low cost silver jacket Super-flex Columbia branded coax I bought back in the 70's during the CB boom... Some of the cheaper coax brands have less than about 70% shielding making them pretty leaky to rf. It works just killer for adding a little extra signal horse-power to a carrier current broadcast station. Radiax without trying... :-) cheers, skipp Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: RE: [Repeater-Builder] Re: Duplexers
I^2R losses do change with frequency because of the skin effect. On 8/26/07, Ron Wright [EMAIL PROTECTED] wrote: Jeff, The low shield coverage is one reason I do not buy cables with pre-installed connectors unless I know the cable...not just because it says RG8 or whatever. I used a piece of 50 ft RS RG8 w/pre-installed connectors for a few years and finally cut it for other purposes and was so disappointed I had purchased such a cable with so little shield. Guess works for CB and Ham HF bands, but really not good for VHF/UHF. The same can be said for many PL259 connectors and adapters. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] jeff%40depolo.net Date: 2007/08/26 Sun PM 12:59:45 CDT To: Repeater-Builder@yahoogroups.com Repeater-Builder%40yahoogroups.com Subject: RE: [Repeater-Builder] Re: Duplexers Coax leakage is different than currents flowing on the shield though... I remember having some RG8 from Radio Shack with braid openings that you could probably fit a pencil through. Some of the cheaper coax brands have less than about 70% shielding making them pretty leaky to rf. It works just killer for adding a little extra signal horse-power to a carrier current broadcast station. Radiax without trying... You could run it up the tower and have a really long antenna. Lots of capture area ;-) Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: Re: RE: [Repeater-Builder] Re: Duplexers
Jesse, You are correct and this is why some large coax have hollow tubing for the inter conductor. Due to skin effect the current density on the outer part of the conductor is higher. But if a coax has 10 watts with a said current at one freq and the same current at a higher freq the losses will be different. This was my point. 73, ron, n9ee/r From: Jesse Lloyd [EMAIL PROTECTED] Date: 2007/08/26 Sun PM 02:34:41 CDT To: Repeater-Builder@yahoogroups.com Subject: Re: RE: [Repeater-Builder] Re: Duplexers I^2R losses do change with frequency because of the skin effect. On 8/26/07, Ron Wright [EMAIL PROTECTED] wrote: Jeff, The low shield coverage is one reason I do not buy cables with pre-installed connectors unless I know the cable...not just because it says RG8 or whatever. I used a piece of 50 ft RS RG8 w/pre-installed connectors for a few years and finally cut it for other purposes and was so disappointed I had purchased such a cable with so little shield. Guess works for CB and Ham HF bands, but really not good for VHF/UHF. The same can be said for many PL259 connectors and adapters. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] Date: 2007/08/26 Sun PM 12:59:45 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Duplexers Coax leakage is different than currents flowing on the shield though... I remember having some RG8 from Radio Shack with braid openings that you could probably fit a pencil through. Some of the cheaper coax brands have less than about 70% shielding making them pretty leaky to rf. It works just killer for adding a little extra signal horse-power to a carrier current broadcast station. Radiax without trying... You could run it up the tower and have a really long antenna. Lots of capture area ;-) Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome. Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: RE: [Repeater-Builder] Re: Duplexers
Jeff, The low shield coverage is one reason I do not buy cables with pre-installed connectors unless I know the cable...not just because it says RG8 or whatever. I used a piece of 50 ft RS RG8 w/pre-installed connectors for a few years and finally cut it for other purposes and was so disappointed I had purchased such a cable with so little shield. Guess works for CB and Ham HF bands, but really not good for VHF/UHF. The same can be said for many PL259 connectors and adapters. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] Date: 2007/08/26 Sun PM 12:59:45 CDT To: Repeater-Builder@yahoogroups.com Subject: RE: [Repeater-Builder] Re: Duplexers Coax leakage is different than currents flowing on the shield though... I remember having some RG8 from Radio Shack with braid openings that you could probably fit a pencil through. Some of the cheaper coax brands have less than about 70% shielding making them pretty leaky to rf. It works just killer for adding a little extra signal horse-power to a carrier current broadcast station. Radiax without trying... You could run it up the tower and have a really long antenna. Lots of capture area ;-) Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: Re: RE: [Repeater-Builder] Re: Duplexers
Well skin effect varies with frequency, there for the R is higher with frequency. I is constant, but R is not, so your power lost will vary with frequency because of I^2R and skin effect. This is why larger diameter solid hardline has less loss than smaller. On 8/26/07, Ron Wright [EMAIL PROTECTED] wrote: Jesse, You are correct and this is why some large coax have hollow tubing for the inter conductor. Due to skin effect the current density on the outer part of the conductor is higher. But if a coax has 10 watts with a said current at one freq and the same current at a higher freq the losses will be different. This was my point. 73, ron, n9ee/r From: Jesse Lloyd [EMAIL PROTECTED] ve7lyd%40gmail.com Date: 2007/08/26 Sun PM 02:34:41 CDT To: Repeater-Builder@yahoogroups.com Repeater-Builder%40yahoogroups.com Subject: Re: RE: [Repeater-Builder] Re: Duplexers I^2R losses do change with frequency because of the skin effect. On 8/26/07, Ron Wright [EMAIL PROTECTED] mccrpt%40verizon.net wrote: Jeff, The low shield coverage is one reason I do not buy cables with pre-installed connectors unless I know the cable...not just because it says RG8 or whatever. I used a piece of 50 ft RS RG8 w/pre-installed connectors for a few years and finally cut it for other purposes and was so disappointed I had purchased such a cable with so little shield. Guess works for CB and Ham HF bands, but really not good for VHF/UHF. The same can be said for many PL259 connectors and adapters. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] jeff%40depolo.net Date: 2007/08/26 Sun PM 12:59:45 CDT To: Repeater-Builder@yahoogroups.comRepeater-Builder%40yahoogroups.com Subject: RE: [Repeater-Builder] Re: Duplexers Coax leakage is different than currents flowing on the shield though... I remember having some RG8 from Radio Shack with braid openings that you could probably fit a pencil through. Some of the cheaper coax brands have less than about 70% shielding making them pretty leaky to rf. It works just killer for adding a little extra signal horse-power to a carrier current broadcast station. Radiax without trying... You could run it up the tower and have a really long antenna. Lots of capture area ;-) Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome. Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
Re: [Repeater-Builder] Cleaning of Moto 1500 series dup.s
At 05:22 AM 08/26/07, you wrote: What are some of the methods that you folks have used in cleaning these cans...solvents, any anti-crud stuff afterward? Have any of you used Tarn-X and ACF-50 before? (http://www.corrosion-control.com/acf50.html) Just curious of results. Thanks, Robert Go to this web page http://www.repeater-builder.com/motorola/t1500.html and look for the Cactus Radio tech note that is referenced there. It has a cleaning procedure. If you are overhauling one, why not take a lot of photos and write up your experience ?
[Repeater-Builder] Ford E350 installation
I'm helping a friend with his vehicle Anybody have experience in mounting antennas in the roof of a 2002 E350 stretch van (15 passenger)? It apparently has an air duct down the center of the ceiling (it has the rear air) and before I start tearing the vehicle apart I'd like to ask if anybody has been there, done that ?? This will be a same-day installation - I'll not be able to tear it apart and wait to get parts. Current idea is a GPS antenna, an NMO or two and maybe a cellphone antenna. Ideas welcome via the list or private email. Mike
[Repeater-Builder] Re: Cleaning of Moto 1500 series dup.s
Oh my god DO NOT USE OR TAKE THE CACTUS PAGE INFORMATION AS GOSPEL. Page 3 and 4 information is a real train-wreck... Do not wire wheel the duplexer plunger as described... products from the wire wheel have a serious potential to embed and become real bad problem sources. You can also damage the plunger surface with scratches, which become real bad news. Anyone using Emory cloth or any type of sand paper inside a duplexer needs to have their head examined. Some time back I posted how I clean and refurbished the T-1500 type cavities... you might go look that post up. skipp Mike Morris WA6ILQ [EMAIL PROTECTED] wrote: Go to this web page http://www.repeater-builder.com/motorola/t1500.html and look for the Cactus Radio tech note that is referenced there. It has a cleaning procedure. If you are overhauling one, why not take a lot of photos and write up your experience ? At 05:22 AM 08/26/07, you wrote: What are some of the methods that you folks have used in cleaning these cans...solvents, any anti-crud stuff afterward? Have any of you used Tarn-X and ACF-50 before? (http://www.corrosion-control.com/acf50.html) Just curious of results. Thanks, Robert
[Repeater-Builder] Re: Ford E350 installation
Same thing with the full size crew cab I just did last Thursday. If you can get your routing speedo cable down the side out of the air duct it should work. But I chose to come down a side post and go under the carpet all the way up. Ford put serious parts of the wire harness in the door floor trays and one of the computers was behind the passenger side front plastic kick panel. I didn't need any stray rf getting into the vehicle electrical system so up under the carpet you go once you get down to the floor level. And you'll just love the double fire-wall in most of the newer trucks and vans. Very well build and tough to get wires into/out-of. cheers, s. Mike Morris WA6ILQ [EMAIL PROTECTED] wrote: I'm helping a friend with his vehicle Anybody have experience in mounting antennas in the roof of a 2002 E350 stretch van (15 passenger)? It apparently has an air duct down the center of the ceiling (it has the rear air) and before I start tearing the vehicle apart I'd like to ask if anybody has been there, done that ?? This will be a same-day installation - I'll not be able to tear it apart and wait to get parts. Current idea is a GPS antenna, an NMO or two and maybe a cellphone antenna. Ideas welcome via the list or private email. Mike
RE: Re: RE: [Repeater-Builder] Re: Duplexers
Jesse is right about skin effect being greater at higher frequencies on the same cable. But current will be less also as resistance increases. Current is a function of resistance for a given amount of power applied. Coax loss is mainly due to resistive loss up thru VHF. Dielectric loss also starts to come into play as you get into UHF and above. The higher the frequency the higher the resistance is in the cable conductor due to skin effect. Losses due to radiation are very low and almost immeasurable in most cases. Open wire line will radiate very little if it is properly balanced even when SWR is very high. The reason open wire line has less loss than coax cable is that the impedance is generally higher. The higher the impedance the lower the current for a given amount of power thus the lower the I squared R loss in the line. (Note that the R in I squared R loss is talking about the resistive loss in the cable and not the impedance of the cable) A 75 ohm coax cable with the same approximate size as a 50 ohm cable will have lower loss than the 50 ohm cable because of the lower current in the cable. (Less I squared R loss) In coax cable the loss is mainly determined by the center conductor size/surface area. Current flow is very shallow at RF frequencies so it does not matter if center conductor is solid or tubing. Tubing gets more economical with larger sizes. As the center conductor size is increased in a cable the shield must also be increased in order to maintain the same center conductor to shield diameter ratio which maintains the impedance. If the center conductor size was increased without changing the outer conductor the impedance of the cable would be lower. Losses due to SWR on the line are due to part of the signal being reflected and re-reflected and suffering additional resistive losses as it makes the second (and multiple) trip up and down the line. This is not to be confused with mis-match loss. Mis-match loss is not a loss attributable to cable loss but it is a loss that comes about because the transmitter does not see a flat 50 ohms and does not transfer full power because the loading has changed due to the impedance mis- match. This type of loss is what is seen due to poor connectors. Often connector mis-match loss is confused with direct loss in the connector. Direct loss produces heat as does all I squared R loss. 73 Gary K4FMX _ From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] On Behalf Of Jesse Lloyd Sent: Sunday, August 26, 2007 3:32 PM To: Repeater-Builder@yahoogroups.com Subject: Re: Re: RE: [Repeater-Builder] Re: Duplexers Well skin effect varies with frequency, there for the R is higher with frequency. I is constant, but R is not, so your power lost will vary with frequency because of I^2R and skin effect. This is why larger diameter solid hardline has less loss than smaller. On 8/26/07, Ron Wright [EMAIL PROTECTED] wrote: Jesse, You are correct and this is why some large coax have hollow tubing for the inter conductor. Due to skin effect the current density on the outer part of the conductor is higher. But if a coax has 10 watts with a said current at one freq and the same current at a higher freq the losses will be different. This was my point. 73, ron, n9ee/r From: Jesse Lloyd [EMAIL PROTECTED] mailto:ve7lyd%40gmail.com Date: 2007/08/26 Sun PM 02:34:41 CDT To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: Re: RE: [Repeater-Builder] Re: Duplexers I^2R losses do change with frequency because of the skin effect. On 8/26/07, Ron Wright [EMAIL PROTECTED] mailto:mccrpt%40verizon.net wrote: Jeff, The low shield coverage is one reason I do not buy cables with pre-installed connectors unless I know the cable...not just because it says RG8 or whatever. I used a piece of 50 ft RS RG8 w/pre-installed connectors for a few years and finally cut it for other purposes and was so disappointed I had purchased such a cable with so little shield. Guess works for CB and Ham HF bands, but really not good for VHF/UHF. The same can be said for many PL259 connectors and adapters. 73, ron, n9ee/r From: Jeff DePolo [EMAIL PROTECTED] mailto:jeff%40depolo.net Date: 2007/08/26 Sun PM 12:59:45 CDT To: Repeater-Builder@yahoogroups.com mailto:Repeater-Builder%40yahoogroups.com Subject: RE: [Repeater-Builder] Re: Duplexers Coax leakage is different than currents flowing on the shield though... I remember having some RG8 from Radio Shack with braid openings that you could probably fit a pencil through. Some of the cheaper coax brands have less than about 70% shielding making them pretty leaky to rf. It works just killer for adding a little extra signal horse-power to a carrier current broadcast station. Radiax without trying... You could run it up the tower and have a really long antenna. Lots of capture area ;-) Ron Wright, N9EE 727-376-6575
RE: [Repeater-Builder] Re: Duplexers
Holy Cow!! Get out your Smith charts!:-) Thanks for the answers. Be careful what you ask for... Thanks to Kevin at Repeater Builder as well. IMHO still the best repeater info site. 73 Bernie Parker K5BP
