The UHF I remember was 4CX250B's but that was earlier. 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 18:33:15 -0800 (GMT-08:00) >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 > > > > > > 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/
