RE: [Repeater-Builder] Caution on Bomar Crystals

[Paul Finch]

This brings up an interesting memory, I worked at a nationwide paging company and was moved back into repair manager after the new manager guy was fired.  (He got caught listening in  on a private conversation with a Telco buttset between a tech and the President of the company)  I started the shop and then they hired a new guy to release me for more important assignment.  After a couple months the reliability of the repaired pagers went from 2 to 3 % to a whopping 97% dead when they were returned to the field!  The guy was a real winner!   After I got settled back in my old office about 35 miles closer to my house I started talking to the techs and following what this new guy had them doing.  Under his instruction they were to monitor the analog audio out of the pager with an oscilloscope and "tune" the 1st oscillator until the scope triggered!  I asked how and where do they know where to set the trigger to get the frequency correct?  They all said they did not know, it's just way the shop manager said it had to be done!  I found the pagers were way off frequency.  What I did is come up with a RF sniffer and the calculations of each model of pager's injection frequency so they could read the injection frequency out on the service monitor.  I personally don't like the injection method of setting the frequency but it was the most simple way for the techs we had at the time.   This one change took the failure rate from 97% to 2 to 3% in two weeks, a complete reversal!  My job was done.   Paul         -----Original Message----- From: Repeater-Builder@yahoogroups.com [mailto:[EMAIL PROTECTED]On Behalf Of Kevin Custer Sent: Thursday, May 12, 2005 1:30 PM To: Repeater-Builder@yahoogroups.com Subject: Re: [Repeater-Builder] Caution on Bomar Crystals Expensive: Mototola Mitrek recrystal and tempco at ICM: $50.00/element. Bomar is $35.00. West is appx. $32.00. There was a debate regarding West Crystal's alleged "temperature compensation" a week or two ago on here. Check the archives - I forget the conclusion, if any. Bob NO6B The figures above that Steve-WA6ZFT gave are incorrect.  Bomar charges $25 to re-crystal and TC "your" element, not $35 YMMV, but in a direct conversation with a person claiming to be an engineer at West, I wasn't convinced that they actually TC the crystal in the element/ICOM.  Only after a VERY lengthy discussion and proving that I knew the difference between TC'ing and "netting" did he admit to only changing the parallel capacitor to achieve "on frequency" with the trimmer centered.  His thought was this measure was "compensating" the element.  After that, I was uncertain that West Crystal actually knew what proper ICOM or Channel Element TC'ing really was. I was also not convinced that they check the modulation linearity or characteristics when redoing a FM TX element, something that I know ICM and Bomar does.  Does West Crystal do this,  I don't know, and I'm not going to call yet again to find out.  I was very discouraged from talking to them the first time, as I think they were trying to buffalo me into thinking I was getting something I'm convinced they weren't giving. In crystals and crystal companies, you get what you pay for.... Again, YMMV, and likely will. Kevin 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 the Yahoo! Terms of Service.