Eric, Thanks for the reply Lab is not equal to testing lab but is OK. Cumex were cheap crystals and managed to compensate ok. Bomar which everyone seems to recommend makes much better crystals. I have a small oven and an ERI counter good to .1 hz at 440. I can cycle and adjust within reason.
Ralph -------------- Original message ---------------------- From: "Eric Lemmon" <[EMAIL PROTECTED]> > Ralph, > > Before you make a decision on your supplier, please read the following > article: > > <www.repeater-builder.com/tech-info/temperature-compensation.html> > > Unless you have a testing laboratory equal to that found in a commercial > crystal house, I suspect that your "good luck" is more likely "blind luck", > and does not justify putting new crystals in previously-compensated channel > elements. I and many others believe that the $30 extra spent for a full > compensation is money well spent. Otherwise, your crystal that you think is > doing just fine may have deficiencies that you don't know about, and don't > have the equipment to detect. > > I'm not just talking about rare cases here- a local 220 repeater was > notorious for drifting rapidly off frequency during extended net operation > and distorted audio. It was a converted Mastr II that the owner recrystaled > himself. When confronted with the complaint that the frequency drifted, he > was in denial because he said he bought the crystal from ICM! Once the > crystal was sent back to ICM with the ICOM and fully compensated for $30, > the repeater worked perfectly. Not only was the drifting problem solved, > but the audio clarity was profoundly improved. It seems that the ICOM was > originally compensated for a factory-made crystal that had different > characteristics from the new crystal made by ICM. Since ICM was not given > the ICOM in advance, ICM had no way to test or modify the ICOM to work > properly with the new crystal. In my book, it makes sense to always get the > full compensation of a new crystal to the ICOM or channel element. > > 73, Eric Lemmon WB6FLY > > > -----Original Message----- > From: Repeater-Builder@yahoogroups.com > [mailto:[EMAIL PROTECTED] On Behalf Of [EMAIL PROTECTED] > Sent: Saturday, November 03, 2007 5:22 PM > To: Repeater-Builder@yahoogroups.com > Subject: [Repeater-Builder] Crystals Motorola etc > > Hi All > > Looking for information on who makes crystals for channel elements. > > Micor's and Mitrek > > Yes, I know that International makes them but the price is high. > > I have had good luck putting crystals in old channel elements and changing > the caps as necessary > > to achieve reasonable stability. Used to use CUMEX in El Paso but they seem > to be gone > > Ralph, W7HSG > >
--- Begin Message ---
Ralph,
Before you make a decision on your supplier, please read the following
article:
<www.repeater-builder.com/ tech-info/ temperature- compensation. html>
Unless you have a testing laboratory equal to that found in a commercial
crystal house, I suspect that your "good luck" is more likely "blind luck",
and does not justify putting new crystals in previously-compensated channel
elements. I and many others believe that the $30 extra spent for a full
compensation is money well spent. Otherwise, your crystal that you think is
doing just fine may have deficiencies that you don't know about, and don't
have the equipment to detect.
I'm not just talking about rare cases here- a local 220 repeater was
notorious for drifting rapidly off frequency during extended net operation
and distorted audio. It was a converted Mastr II that the owner recrystaled
himself. When confronted with the complaint that the frequency drifted, he
was in denial because he said he bought the crystal from ICM! Once the
crystal was sent back to ICM with the ICOM and fully compensated for $30,
the repeater worked perfectly. Not only was the drifting problem solved,
but the audio clarity was profoundly improved. It seems that the ICOM was
originally compensated for a factory-made crystal that had different
characteristics from the new crystal made by ICM. Since ICM was not given
the ICOM in advance, ICM had no way to test or modify the ICOM to work
properly with the new crystal. In my book, it makes sense to always get the
full compensation of a new crystal to the ICOM or channel element.
73, Eric Lemmon WB6FLY
-----Original Message-----
From: Repeater-Builder@yahoogroups. com
[mailto:Repeater-Builder@yahoogroups. ] On Behalf Of [EMAIL PROTECTED]com net
Sent: Saturday, November 03, 2007 5:22 PM
To: Repeater-Builder@yahoogroups. com
Subject: [Repeater-Builder] Crystals Motorola etc
Hi All
Looking for information on who makes crystals for channel elements.
Micor's and Mitrek
Yes, I know that International makes them but the price is high.
I have had good luck putting crystals in old channel elements and changing
the caps as necessary
to achieve reasonable stability. Used to use CUMEX in El Paso but they seem
to be gone
Ralph, W7HSG
--- End Message ---
