The KB6MIP/R Project Page

Works in progress in the MIP Shop

Update 8 June 2025

This is the last major assembly for the KB6MIP repeater in Talent, Oregon. It is an Alcatel 403-470 MHz UHF Intermod Panel.

Originally marketed by Motorola as an option for the Quantar series of base / repeater stations, it is a sturdy unit which can more than handle the 30 watt amplifier in the Daniels station. The 50 ohm load that absorbs the reflected power from the antenna is bonded to a heat sink, which in turn has a fan mounted to it for effective cooling in a rack. Unfortunately, this is cooling system was designed to be externally monitored and controlled by the Quantar station. There is a thermistor mounted to the heatsink as well, but the lead from it, and the power leads for the fan, end at a ten-pin connector. So I have to build a temperature-controlled switch that will monitor the temperature of the load heatsink and enable or disable the fan accordingly. Or, maybe, just have the fan come on whenever the Daniels PA is operational. That may be preferable, and easier to implement. That may consume a bit more utility power, but ... it's a hobby. It's supposed to consume all my discretionary funds, right?

There was also no provision for PA power being fed to the input of the circulator. I have mounted a Nf-Nf bulkhead connector to the back of the tray, next to the existing port which is the output feed point to the antenna. I thought about cobbing up a short piece of LMR240 to make that connection, but now I'm wondering if I should try and find cables of the same type that are in the panel. Trouble is, they are not marked, so other than "teflon coated, quarter inch," I don't have much to go on, specification-wise. The existing cables do have a part number tag which reads:
0112004C02/P
0534 409529
No manufacturer logo or any other form of ID is to be found.

I hope to get the fan and cabling situation squared away fairly quickly so I can get this panel in service. I'll let you all know how that works out ...

Stay tuned!

Update 24 January 2025

Above you see the current configuration of the KB6MIP/R repeater in Talent, Oregon.

Top to bottom:

Shelf 1 is a Daniels SR-39-1 subrack containing the VHF remote base on 146.5200 MHz. Left to right in the subrack are an AC-3E audio Control module, a VT-3/160-SWA800 transmitter module, a VR-3/160-SWA200 receiver module, a VT-3H045-SWA300 transmitter module (awaiting conversion to the six meter amateur band), a UT-3H045-SWA200 receiver module (also awaiting conversion to the six meter amateur band), and finally an SM-3B system monitor module.

Shelf 2 is also a Daniels SR-39-1 subrack, containing the KB6MIP/R repeater. It is programmed on the ORRC LARS channel (440.7500 MHz output, 445.7500 MHz input) decoding and encoding CTCSS 82.5 Hz. Left to right in the subrack are an AC-3E audio Control module, a UT-3/460-SNA200 transmitter module (modified per factory documentation for wideband), a UR-3/460-SWC200 receiver module, an AMP-2/450-3000 power amplifier (adjusted for 20 watts output), and finally an SM-3 system regulator.

The next item down the rack is the latest update, a Motorola T-1500 4-bay band-pass / band-reject duplexer. This replaced the EMR "pocket duplexer," which was basically a four bay notch filter. The system worked OK with that, but the T1500 is a much better device. Insertion loss on both channels was around -1.4 dB, and the opposite channel rejection notches were around -95dB. The front panel has seen a hard life, but the individual filters that make up the duplexer are in great shape.

Below the duplexer is the S-Com 7330 controller.

I still need to buy or build an intermodulation panel, which has become the final priority on my upgrade list. The critical parts necessary to make one are a circulator (tuned for the 420 - 450 MHz band or wider) and a second harmonic filter (pass band 420 - 450 MHz or wider). If you know anyone who has that kind of gear available, please let me know.

That's all for now. Stay tuned!

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