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
<*> 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/
