Some do ... earlier ones do not ... except on UHF ??? Neil
---- Original Message ---- From: [EMAIL PROTECTED] To: [email protected] Subject: RE: [Repeater-Builder] Re: Motorola Micro 1?4 kilowatt Repeater Date: Mon, 20 Mar 2006 10:39:34 -0800 (GMT-08:00) >I thought these 1/4KW amps used 8560A tubes?? > >-----Original Message----- >>From: [EMAIL PROTECTED] >>Sent: Mar 20, 2006 9:28 AM >>To: [email protected] >>Subject: RE: [Repeater-Builder] Re: Motorola Micro 1?4 kilowatt >Repeater >> >> >> I don't know about the later models but when I was servicing >> the 100 - 275 - 375 watt transmitters, careful maintenance of the >> blower motor was necessary. When you determine the blower motor >> seems to be slowing down ( lack of bearing lubrication? ) try >> that first. >> >> If that doesn't do any good, then a trip to the local electric >> motor repair/rewind shop is necessary. Early on, I used to take >> the entire motor to that shop - later years and since we had >> 30-35 blower motors in various systems everywhere, I got to the >> point of disassembling the motor at our shop and taking the >> armature to the motor shop for a bearing change. They had the >> bearing press, and the skill, we didn't. >> >> Hope this helps / others probably have different ideas. Whatever >> works for you is best. >> >> >> In regards to the pair of 4CX250B's - those tubes require serious >> air circulation. If the blower motor needs servicing, the air >> filter is dirty or the fins of the tubes are plugged with dirt, >> the tubes will have a very short life. >> >> Remember, keep all contacts on that tube socket very clean, >> properly tensioned, for best performance and reliability. >> >> Another item to be aware of is the 4CX250B filament voltage. The >> required filament voltage is 6.0 Volts (not 6.3 Volts) at 2.6 >> amperes. Absolute minimum heating time is 30 seconds. Careful >> attention to the correct filament voltage will give longer life >> than if you don't. >> >> I am reading from the RCA loose-leaf lay-flat Vacuum Tube >> Engineering Manual. >> >> The tube, properly installed, requires an air-system socket ... >> with the use of a ceramic chimney to direct the air coming through >> the socket to pass through the plate cooling fins. >> >> Hope this helps, >> >> Neil - WA6KLA >> >> >>---- Original Message ---- >>From: [EMAIL PROTECTED] >>To: [email protected] >>Subject: RE: [Repeater-Builder] Re: Motorola Micro 1?4 kilowatt >>Repeater >>Date: Mon, 20 Mar 2006 16:33:14 -0000 >> >>>Ahhh... the famous Motorola 1/4kw dual 4cx250b final? >>>Never saw one that held up long term without regular >>>hands-on service. Hard to keep a blower going in some >>>of the earlier units. >>> >>>You're going to love trouble-shooting the safety interlock >>>circuits connected to the power supply. Just a bit more >>>fun than working on an MSY or MHB repeater/base. >>> >>>cheers, >>>skipp >>> >>>> "ke4ovn" <[EMAIL PROTECTED]> wrote: >>>> Hello Group: >>>> Looking on information on A motorola micro repeater, >>>> 2 tube final Model Number-B93rcb-31058.On 2meter >>>> band now, Tube final drop from 250watts to 30 watts. >>>> Need to find a manual number so I can troubleshoot. >>>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>>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/
