Fwd: RE: Re: [Repeater-Builder] Micor mobile transmitter
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Re: [Repeater-Builder] Micor mobile transmitter
Larry - I've taken 450-470 MHz Micor 25 watt mobiles & ran them on only the pre-driver to get about 9 watts out (I bypassed the rest of the PA deck). I also had to bypass the power control board to make it work reliably. -- Original Message -- > "[EMAIL PROTECTED]" wrote: > > > > I have a couple of 100-Watt, 406-420 MHz MICOR Mobile radios. I > > picked them up at Dayton a few years ago since they were very > > inexpensive, and hoped that I could use them as some link radios. > > I'd like to find out how to use just the low power sections of the > > 100-watt mobile PA deck, as they would be running a high duty cycle. > > For the distance I'd be covering, 25 -50 watts or even much less > > would be overkill. Trying to find 406-420 MHz range 25 or 45 watt > > PAs to swap out has so far been impossible, so I'm hoping someone > > has disabled the last few PA deck sections to run them at lower > > power, and still has some notes on how they did any matching, etc. > > Larry Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Micor mobile transmitter
I agree with Neil's comments, and have had similar experience and luck doing so. There really isn't anything to it, much easier than the "Hack-Saw 10 watt VHF IPA" Kevin Neil McKie wrote: > Although I haven't experimented with the 406-420 Micors, I have > done some trouble shooting on the 450-470 MHz Series. I discovered > all of the PA deck micro-strip amplifiers are 50 ohm impedance in > and out. > > In my opinion, if you have sufficient output protection between > the last amplifier and the antenna, I would believe you could just > bypass the later PA amps and use the earlier stages for your > project. > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Micor mobile transmitter
I have not done this on a 420 Micor, but I have on a 450 Micor, which is essentially the same. As Neil pointed out, all the interstage coupling is done at 50 ohms, so you only need to decide how much power you need, and modify accordingly. The controlled stage will put out 2 to 7 watts, if you put your output there. The next stage will put out 6 to 15 watts or so. The next stage will put out 20-45 watts, and the whole thing will put out 110 watts. If you want to go for less than 10 watts out, you need to modify the power control board by changing a couple of resistors (or paralleling them on the board, which is easier). If you can get by with 10-15 watts, I would bypass the last two stages, and the radio will run cool as a cucumber, no fan needed (and draw a lot less power). Joe --- "[EMAIL PROTECTED]" <[EMAIL PROTECTED]> wrote: > I have a couple of 100-Watt, 406-420 MHz MICOR > Mobile radios. I picked them up at Dayton a few > years ago since they were very inexpensive, and > hoped that I could use them as some link radios. I'd > like to find out how to use just the low power > sections of the 100-watt mobile PA deck, as they > would be running a high duty cycle. For the distance > I'd be covering, 25 -50 watts or even much less > would be overkill. Trying to find 406-420 MHz range > 25 or 45 watt PAs to swap out has so far been > impossible, so I'm hoping someone has disabled the > last few PA deck sections to run them at lower > power, and still has some notes on how they did any > matching, etc. > Larry > > __ Do You Yahoo!? Tired of spam? Yahoo! Mail has the best spam protection around http://mail.yahoo.com Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Micor mobile transmitter
Although I haven't experimented with the 406-420 Micors, I have done some trouble shooting on the 450-470 MHz Series. I discovered all of the PA deck micro-strip amplifiers are 50 ohm impedance in and out. In my opinion, if you have sufficient output protection between the last amplifier and the antenna, I would believe you could just bypass the later PA amps and use the earlier stages for your project. You have the manual for that radio? Should be 68P81015E70 Hope this helps, Neil - WA6KLA "[EMAIL PROTECTED]" wrote: > > I have a couple of 100-Watt, 406-420 MHz MICOR Mobile radios. I > picked them up at Dayton a few years ago since they were very > inexpensive, and hoped that I could use them as some link radios. > I'd like to find out how to use just the low power sections of the > 100-watt mobile PA deck, as they would be running a high duty cycle. > For the distance I'd be covering, 25 -50 watts or even much less > would be overkill. Trying to find 406-420 MHz range 25 or 45 watt > PAs to swap out has so far been impossible, so I'm hoping someone > has disabled the last few PA deck sections to run them at lower > power, and still has some notes on how they did any matching, etc. > Larry > > -Original Message- > From: Eric Lemmon <[EMAIL PROTECTED]> > Sent: May 10, 2005 6:26 PM > To: Repeater-Builder@yahoogroups.com > Subject: Re: [Repeater-Builder] Micor mobile transmitter > > Bruce, > > Although you can disconnect half of the four final transistors and change > the matching components appropriately to have a 50 watt PA, it's better to > simply exchange the 100W amplifier board for a lower power board. I'm > guessing that you could probably find someone to swap boards with, maybe > even make a few bucks in the deal.. > > It is not a good idea to reduce either the drive level or the PA supply > voltage to achieve a lower power output, because the PA can become > unstable. A solid-state PA is normally designed to present a stable > source impedance which, in basic terms, is directly proportional to supply > voltage and inversely proportional to PA current. Reducing the drive > level will reduce PA current, thus raising the apparent PA source > impedance and causing a mismatch with the load impedance- usually the > reactive input impedance of a duplexer. This is not good, and is an > invitation to instability. Reducing the supply voltage has the opposite > effect on the apparent PA source impedance. > > If you have the requisite test equipment and time, you may be able to > adjust both the drive level and the PA supply voltage to achieve stability > at a lower power output level. This is a lot of work, and may be much > more work than simply replacing the PA board. > > 73, Eric Lemmon WB6FLY > > brucenanney wrote: > > > What is the best way to reduce power on a 100 watt micor mobile for > > repeater use? I have reduced the voltage in to 12.8 volts and have > > developed a cooling system on the P.A. deck that has constant air flow > > over the circuit board as well as the the heatsink. > > Thanks, Bruce KD4BOH. > > > > > > Yahoo! Groups Links > > > > > > > > > > > Yahoo! Groups Links > > > > > Yahoo! Groups Links > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Micor mobile transmitter
I have a couple of 100-Watt, 406-420 MHz MICOR Mobile radios. I picked them up at Dayton a few years ago since they were very inexpensive, and hoped that I could use them as some link radios. I'd like to find out how to use just the low power sections of the 100-watt mobile PA deck, as they would be running a high duty cycle. For the distance I'd be covering, 25 -50 watts or even much less would be overkill. Trying to find 406-420 MHz range 25 or 45 watt PAs to swap out has so far been impossible, so I'm hoping someone has disabled the last few PA deck sections to run them at lower power, and still has some notes on how they did any matching, etc. Larry -Original Message- From: Eric Lemmon <[EMAIL PROTECTED]> Sent: May 10, 2005 6:26 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Micor mobile transmitter Bruce, Although you can disconnect half of the four final transistors and change the matching components appropriately to have a 50 watt PA, it's better to simply exchange the 100W amplifier board for a lower power board. I'm guessing that you could probably find someone to swap boards with, maybe even make a few bucks in the deal.. It is not a good idea to reduce either the drive level or the PA supply voltage to achieve a lower power output, because the PA can become unstable. A solid-state PA is normally designed to present a stable source impedance which, in basic terms, is directly proportional to supply voltage and inversely proportional to PA current. Reducing the drive level will reduce PA current, thus raising the apparent PA source impedance and causing a mismatch with the load impedance- usually the reactive input impedance of a duplexer. This is not good, and is an invitation to instability. Reducing the supply voltage has the opposite effect on the apparent PA source impedance. If you have the requisite test equipment and time, you may be able to adjust both the drive level and the PA supply voltage to achieve stability at a lower power output level. This is a lot of work, and may be much more work than simply replacing the PA board. 73, Eric Lemmon WB6FLY brucenanney wrote: > What is the best way to reduce power on a 100 watt micor mobile for > repeater use? I have reduced the voltage in to 12.8 volts and have > developed a cooling system on the P.A. deck that has constant air flow > over the circuit board as well as the the heatsink. > Thanks, Bruce KD4BOH. > > > Yahoo! Groups Links > > > > Yahoo! Groups Links Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Micor mobile transmitter
One time a few years ago, one of the now lurkers on this remailer, brought his 100 watt high-band Mocom-70 to me to tune up for him. On a lark, I decided to run it wide open in this case with 16 Volts DC. Wide open, the 100 watt transmitter put out 240 watts. Ran my 100 watt UHF Micor wide open ... quit at 130 watts out as I ran out of power supply. Neil - WA6KLA Kevin Custer wrote: > > Bruce Nanney wrote: > > >Thanks Eric and Brian for the info. I've been able to run it for 10 yrs @110 > >watts on 145.270 without any problems in an air conditioned environment. But > >I'm moving it to a remote location without a/c. I guess I will leave it as > >is, as I need the power as much as I can get. No duplexer on this machine. > >Wide area crossband 8 rx site system. > >Thanks again guys, Bruce KD4BOH. > > > > Remember, the *Mobile* has a thermistor in the Power Set Control to > reduce the power level with increasing heat. > Run her wide open and blow some fans on it > > Kevin > > > Yahoo! Groups Links > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Micor mobile transmitter
Bruce Nanney wrote: >Thanks Eric and Brian for the info. I've been able to run it for 10 yrs @110 >watts on 145.270 without any problems in an air conditioned environment. But >I'm moving it to a remote location without a/c. I guess I will leave it as >is, as I need the power as much as I can get. No duplexer on this machine. >Wide area crossband 8 rx site system. >Thanks again guys, Bruce KD4BOH. > Remember, the *Mobile* has a thermistor in the Power Set Control to reduce the power level with increasing heat. Run her wide open and blow some fans on it Kevin Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Micor mobile transmitter
brucenanney wrote: >What is the best way to reduce power on a 100 watt micor mobile for >repeater use? I have redused the voltage in to 12.8 volts and have >developed a cooling system on the P.A. deck that has constant air flow >over the circut board as well as the the heatsink. > Thanks, Bruce KD4BOH. > How much do you want to reduce it? Kevin Custer Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Micor mobile transmitter
Thanks Eric and Brian for the info. I've been able to run it for 10 yrs @110 watts on 145.270 without any problems in an air conditioned environment. But I'm moving it to a remote location without a/c. I guess I will leave it as is, as I need the power as much as I can get. No duplexer on this machine. Wide area crossband 8 rx site system. Thanks again guys, Bruce KD4BOH. - Original Message - From: "Eric Lemmon" <[EMAIL PROTECTED]> To: Sent: Tuesday, May 10, 2005 8:26 PM Subject: Re: [Repeater-Builder] Micor mobile transmitter > Bruce, > > Although you can disconnect half of the four final transistors and change > the matching components appropriately to have a 50 watt PA, it's better to > simply exchange the 100W amplifier board for a lower power board. I'm > guessing that you could probably find someone to swap boards with, maybe > even make a few bucks in the deal.. > > It is not a good idea to reduce either the drive level or the PA supply > voltage to achieve a lower power output, because the PA can become > unstable. A solid-state PA is normally designed to present a stable > source impedance which, in basic terms, is directly proportional to supply > voltage and inversely proportional to PA current. Reducing the drive > level will reduce PA current, thus raising the apparent PA source > impedance and causing a mismatch with the load impedance- usually the > reactive input impedance of a duplexer. This is not good, and is an > invitation to instability. Reducing the supply voltage has the opposite > effect on the apparent PA source impedance. > > If you have the requisite test equipment and time, you may be able to > adjust both the drive level and the PA supply voltage to achieve stability > at a lower power output level. This is a lot of work, and may be much > more work than simply replacing the PA board. > > 73, Eric Lemmon WB6FLY > > brucenanney wrote: > >> What is the best way to reduce power on a 100 watt micor mobile for >> repeater use? I have reduced the voltage in to 12.8 volts and have >> developed a cooling system on the P.A. deck that has constant air flow >> over the circuit board as well as the the heatsink. >> Thanks, Bruce KD4BOH. >> >> >> Yahoo! Groups Links >> >> >> >> > > > > > > > > Yahoo! Groups Links > > > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Micor mobile transmitter
Bruce, Although you can disconnect half of the four final transistors and change the matching components appropriately to have a 50 watt PA, it's better to simply exchange the 100W amplifier board for a lower power board. I'm guessing that you could probably find someone to swap boards with, maybe even make a few bucks in the deal.. It is not a good idea to reduce either the drive level or the PA supply voltage to achieve a lower power output, because the PA can become unstable. A solid-state PA is normally designed to present a stable source impedance which, in basic terms, is directly proportional to supply voltage and inversely proportional to PA current. Reducing the drive level will reduce PA current, thus raising the apparent PA source impedance and causing a mismatch with the load impedance- usually the reactive input impedance of a duplexer. This is not good, and is an invitation to instability. Reducing the supply voltage has the opposite effect on the apparent PA source impedance. If you have the requisite test equipment and time, you may be able to adjust both the drive level and the PA supply voltage to achieve stability at a lower power output level. This is a lot of work, and may be much more work than simply replacing the PA board. 73, Eric Lemmon WB6FLY brucenanney wrote: > What is the best way to reduce power on a 100 watt micor mobile for > repeater use? I have reduced the voltage in to 12.8 volts and have > developed a cooling system on the P.A. deck that has constant air flow > over the circuit board as well as the the heatsink. > Thanks, Bruce KD4BOH. > > > Yahoo! Groups Links > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/Repeater-Builder/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [Repeater-Builder] Micor mobile transmitter
Hi There! Micor mobiles do not like be lowered below 2/3 rated output.. they like to go boom! I had a couple of 100 watters that both went funny even thought I had them in the 60-65 watt range. they were replaced with 40 and 60 watters and those micors are still playing today. I have a fan blowing 100% of the time across the heatsink. I think I have them set at 25 and 40 respectfully. I adjust power with the level control. Hope that this helps! Brian, WD9HSY This info is stuff that this group taught me. pass it on down the line! Yahoo! Groups Links To visit your group on the web, go to:http://groups.yahoo.com/group/Repeater-Builder/ To unsubscribe from this group, send an email to:[EMAIL PROTECTED] Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.
