OK - I was sure my book shows a pair of 8560As for VHF. The UHF ones we had used 8874s. LJ
-----Original Message----- >From: [EMAIL PROTECTED] >Sent: Mar 20, 2006 4:34 PM >To: [email protected] >Subject: RE: [Repeater-Builder] Re: Motorola Micro 1?4 kilowatt Repeater > > > 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 > > > > > > > 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/
