[time-nuts] Repair of PRS10 Lamp Assembly
lists at rtty.us
Sun Mar 17 17:28:38 EDT 2013
I'd fashion a simple loop on the end of a coax and use it to "sniff" the RF in the vicinity of the cell. You are after a relative measure, so simply knowing if it drops with time or not should tell you which way to go in the troubleshooting. Normally a spectrum analyzer is a good device to monitor the loop with, there are other ways to do it as well.
On Mar 17, 2013, at 4:50 PM, Dr. Götz Romahn <goetz at g-romahn.de> wrote:
> thank you for fast responses. As I wrote in my posting, heating seems to be ok as reported by the PRS10 diagnostic tools. I agree with Bob and Paul: RF seems to degrade with warming up, but how can I test this. Remember, lamp and oscillator of PRS10 are not!!! accessible during operation and what part of hte oscillator could be the culprit ( and why do you think it is) ?
> Am 17.03.2013 20:59, :
>> My 2 cents and it is that. The FRS use a higher voltage say 24 V and on
>> ignition that drops back. I have also seen on time-nuts older systems that
>> actually use an ignition voltage to trigger the lamp.
>> But I agree that it sounds like the RF might be low. The bulb does need to
>> be heated to get to the right color temperature also.
>> On Sun, Mar 17, 2013 at 9:03 AM, Bob Camp <lists at rtty.us> wrote:
>>> Unless the PRS10 is very unusual in it's operation there are two things to
>>> check early in the debug process:
>>> 1) Is the oven heating up to roughly the right temperature?
>>> 2) The lamp is lit by RF energy. If the oscillator / amplifier supplying
>>> the RF isn't putting out as much as it should (or what it should) the lamp
>>> will not stay lit.
>>> I'd bet on number 2 in your case. There are many other possibilities, but
>>> I'd check those two first.
>>> On Mar 17, 2013, at 5:22 AM, Dr. Götz Romahn <goetz at g-romahn.de> wrote:
>>>> dear all,
>>>> beeing a silent reader of this list for a while, I now ask my first
>>>> I have obtained a PRS10 that was declared faulty and it is. The problem
>>> I located in lamp assy.
>>>> Lamp ignites only after warming up and pushing by a voltage kick from
>>> abt. 24V to abt 28V on the -24_heat line for some seconds. PRS10 gets
>>> locked there after and rbmon shows a seemingly healthy unit (see
>>> attachment). But... within some 15 to 45 minutes later light from lamp
>>> degrades as seen through "LAMP VIEW" hole in top board as well as AD9
>>> Photocell I/V going down from 1.68 after ignition to 0.158 and lock is lost
>>> of course. Since all heating and voltage diagnostics do stay within
>>> accepted limits I suspect some problem within lamp enclosure (see
>>> attachment). Your help for further diagnosis and any hints for obtaining
>>> spare parts would be appreciated very much.
>>>> Cheers Goetz
>>>> <PRS10 after
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