You are correct. Temperature compensation involves component changes in addition to the crystal.
Chuck WB2EDV ----- Original Message ----- From: DK To: [email protected] Sent: Wednesday, July 11, 2007 3:39 PM Subject: RE: Re: Re: [Repeater-Builder] crystal/channel element compensation.. Ron, You're just adjusting the current frequency of the TX considering the radio temp to match a dead on frequency at 30c/86f chart/curve? I think Chuck is asking how you install the rock and temp compensate the icom assembly to match that same chart. See the bottom of this page. http://www.repeater-builder.com/ge/mastrii/m2icoms.html It's always hot here in Texas so we don't have to worry about it. HI 73 Don W5DK -----Original Message----- From: [email protected] [mailto:[EMAIL PROTECTED] Behalf Of Ron Wright Sent: Wednesday, July 11, 2007 12:12 PM To: [email protected] Subject: Re: Re: Re: [Repeater-Builder] crystal/channel element compensation.. Chuck, This is the procedure GE gives in the maintance manual for the Mastr Exec II. quote""""" A. To hold the setting error to +/-0.6 PPM (which is considered reasonable for 5 PPM crystal oscillators): 1. Maintain the radio at 30 deg C and set the osciallator to desired frequency OR 2. Maintain the radio at 30 deg C (+5 to -15 C) offset the operating frequency as a function of actual temperature, by sthe amount shown in Figure 3 (a graph is given of 15 to 35 degrees C (59 to 95 F) against minus 150 to +300 Hz). A, 1 and 2 are from GE maintence manual. Basically using the chart in the manual one sets the frequency above/below the desired frequency based on rig temp on the bench. For 30 deg C (86 F) this is 0 Hz...for 35 C (95 F) -113 Hz... and 15 C (59 F) set to +300 Hz of frequency. This is for VHF. I assume the crystal manufactures are doing same as to rig specs. Might be different since they probably know temp-to-freq change of their make of crystal. For a more precise element such as 2C GE elements there is a different curve. 73, ron, n9ee/r >From: Chuck Kelsey <[EMAIL PROTECTED]> >Date: 2007/07/11 Wed AM 10:48:18 CDT >To: [email protected] >Subject: Re: Re: [Repeater-Builder] crystal/channel element compensation.. > >Would you be willing to share with the group the process you use to do your >own temperature compensation? > >Chuck >WB2EDV > >----- Original Message ----- >From: "Ron Wright" <[EMAIL PROTECTED]> >To: <[email protected]> >Sent: Wednesday, July 11, 2007 9:47 AM >Subject: Re: Re: [Repeater-Builder] crystal/channel element compensation.. > >> Chuck and all, >> >> I have been using Bomar for last 2 years. I was using ICM, but when they >> bought Sentry they went to a 6 week or more deliever for their 2 week >> service. After about 3 months of this I switched to Bomar and have not >> had any problems. >> >> Both ICM and Bomar make an excellent crystal. We buy the crystal, install >> in elements and temp comp here to GE specs. >> >> One note on Bomar...they have a $50 min so if you buy a pair they are $25 >> ea for 1 week. If you need this fine. However, if you go to 2 weeks the >> crystals are $15 ea. So 2 xtals at 1 week $60 ($10 ship) or 4 crystals at >> 2 weeks $70. If go to 3 weeks the crystals are $10 ea, 6 xtals for $70. >> For some that buy a number of xtals might save some money. >> >> 73, ron, n9ee/r >> >> >> >> >> >>>From: Chuck Kelsey <[EMAIL PROTECTED]> >>>Date: 2007/07/10 Tue PM 09:08:39 CDT >>>To: [email protected] >>>Subject: Re: [Repeater-Builder] crystal/channel element compensation.. >> >>> >>>My last two dealings (within last two years) with Bomar have me skeptical. >>>One GE ICOM had to go back because it was drifting all over the place and >>>I >>>did pay for the temperature compensation. I told them to take their time >>>when I returned it as I wanted it done right. This was a UHF 2C. They had >>>it >>>returned in a little over a week - certainly a bit hurried. >>> >>>I also had some GE crystal elements sent in for re-crystal and temperature >>>compensation and all of them came back with the same comp caps installed. >>>I >>>called and asked their engineering department and was told "they usually >>>work fine with the existing capacitors." It didn't leave me with a warm >>>and >>>fuzzy feeling. >>> >>>Next time back to ICM. >>> >>>Chuck >>>WB2EDV >>> >>>----- Original Message ----- >>>From: "na6df" <[EMAIL PROTECTED]> >>>To: <[email protected]> >>>Sent: Tuesday, July 10, 2007 6:55 PM >>>Subject: [Repeater-Builder] crystal/channel element compensation.. >>> >>>> OK, I usually use International, but how is Bomar doing these days, >>>> quality-wise? ICM seems to be pretty pricey these days. Bomar says $35 >>>> for re-crystalling a channel element. (I assume that means >>>> compensating as well). Thoughts welcome.. >>>> >>>> na6df dave >>>> >>>> >>>> >>>> >>>> >>>> >>>> Yahoo! Groups Links >>>> >>>> >>>> >>>> >>> >>> >> >> >> Ron Wright, N9EE >> 727-376-6575 >> MICRO COMPUTER CONCEPTS >> Owner 146.64 repeater Tampa Bay, FL >> No tone, all are welcome. >> >> >> >> >> >> >> >> Yahoo! Groups Links >> >> >> >> > > Ron Wright, N9EE 727-376-6575 MICRO COMPUTER CONCEPTS Owner 146.64 repeater Tampa Bay, FL No tone, all are welcome.
