Hi Joe,
In past a friend of me give me 2 Cushman CE-4B service monitor and the 2 test-set have rouble with the 5MHz HSO. I have work every night on these famous oscillators to find an open contact on the nichrome wire. To repair the oven I remove one turn of the nichrome wire and retwist the wire on the tab and solder. Maybe it is not the best thing to do but it is cheaper than a new module or other like that, anyway Cushman Company is dead... Caution on the Nichrome wire, it is very small (like hair) and is jacket is made with little Kevlar envelope. I use a 50X microscope to do the job with a little light projector. After a lot of efforts my two monitors work very well and stability is ok, its a quasi miracle. To do that you will need a lot of dexterity and you need to be relaxed, very relaxed. I have a lot of photos and notes about that job maybe it will be a good thing to put that on RB web site? Good luck with your project. 73 Eric VE2VXT PS. Excuse my English I speak French only. _____ De : Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED] De la part de Joe Envoyé : 16 décembre, 2007 21:36 À : Repeater-Builder@yahoogroups.com Objet : [Repeater-Builder] IFR 1500 service monitor, OCXO bit the dust While trying to align a MASTRII , I discovered that my IFR1500 OCXO lost the oven. (or so it seems). Prior to this, I noticed that the frequency was 170Hz off and it could not be netted with the front control. Then, I found it 10Khz off frequency at 450Mhz. Watching the frequency of the 10MHZ oscillator from cold start to 10 minutes warm-up time, I never see the frequency change. This seems to be telling me that the oven has failed in the Oven Controller Crystal Oscillator. (This IFR1500 has Opt 02 installed). I made a call to Auburn Electronics Labs and spoke to William. He was very informative, but gave me an estimate of $1,800 to replace the oven or about $1,000 to retrofit it with a more modern frequency standard. My third option is to always use an external 10Mhz reference source, but the IFR1500 needs 1 to 1.5 volts of signal to switch from the internal to external reference source. A fourth option would be to try to fix the existing oven by repairing or replacing the nichrome wire that probably burned open. I did catch a whiff of something burning near my workbench but never identified what it was, probably was the nichrome wire burning open. Anyone have experience with this kind of problem? Any suggestions? 73, Joe, K1ike > _._,___
