I recently ordered TX and RX crystals from ICM for the MICOR RT Station. I specified the correct FC and FX and catalog # 167380 for MOT KNX1018C TX (132-174). When these crystals were received they would not "net" on frequency. The TX was over 20Khz. high and would not net any closer. I notified ICM and their Customer Service Dept., agreed to replace the TX crystal. When I received this "replacement "crystal, it was over 30Khz. high! I sent another email and got a reply from the owner, Royden Freeland, W5EMH, stating the following:
"To get the crystal to tune properly you will need to change L1 to 2.6-2.7uh and C6 to 1-10 pf depending on the crystal to get it on frequency at close to center trim. Each element was compensated and tuned for the original crystal so if you are changing frequency very far there can be problems. Motorola generally used a crystal load of 32pf in elements with trimmers and varied components within the element to bring it on frequency. ICM will be happy to install the crystal and compensate the element if you would prefer. We would charge $60.00 to install and compensate your element and crystal". I have printed out the channel element schmetic and picture (from W3KCC) repeater-Builders website and see that C6 is the trimmer and L1, but no values are represented. Can anyone tell me what the current value of the inductor L1 is? If it's currently higher in value, can it be "rewound" for the 2.7uH inductance ICM references? I believe there is enough room to insert a fixed cap of proper C in series to drop the tuning range of the C6, to perhaps the 1-10pf. I have looked at Mouser Electronics for a trimmer 1- 10pf and 2.7uH axil-lead inductor, L1without success. If they are available, can you please stear me to where I can purchase one or both? I always thought that you sent ICOM's back for temperature compensation and not for simple exchance of crystals. I have never needed to to that with any GE MASTR series TX & RX or Mocom 70 series or any EF Johnson series that simply required new crystals. But again, that was 20 years ago, which is a long time. Any advice would be appreciated as I don't need to spend another $120 to "install the crystal and compensate the element". TNX is advance...Dennis - W4DG
