Technical Details
Frequency: 145.41MHz
Output frequency is 145.41, input is 144.81. This is the standard 600kHz offset.CTCSS Frequency: 74.4Hz
The CTCSS tone of 74.4Hz is used on receive. Please use this tone when using the Harvard Repeater. We now run with tone required. If you have a radio which does not produce tone, send the code 75* in DTMF tones, and the repeater will respond by turning off tone (a voice announcement will confirm this). The courtesy tone will change to alert users to the operating mode. After a period of inactivity, the CTCSS will be reset. If you want to enable the CTCSS manually before the timer does it, send 76*.The 74.4Hz tone is also encoded on the output of the repeater. Use the CTCSS decode feature of your radio, of available, to limit squelch openings due to enhanced propagation or local interference.
Autopatch: Open
The autopatch facility of the repeater is operated on an open basis. Please do not abuse it! The club pays the phone bill. Ask a control operator for instructions. Club members may have a speed-dial added by request to Dan N1JEB.Equipment: Mitrek Radio, S-Com controller
The exciter is a modified Motorola Mitrek radio. While we first tried running the radio at close to 100 watts with extra cooling, the power amplifier section ultimately failed. We've been through a variety of changes, and at this point have a small amplifier that takes the power from the mitrek exciter and boosts it to around 25 watts.
From there, RF is fed into a separate, larger amplifier. We've been through more than one. The Teletec unit we had for a number of years died. Replacing the transistors helped for a while, but it died again. Our latest amplifier is pictured below:
We hope this new amp will last a while. A note to others building repeaters: the most important thing in buying an amplifier is the length of the warranty, and the availability of an ongoing service contract. Teletec seemed good when we bought, but they went out of business.
The controller is an S-Com 7K, with audio delay module, autopatch and speech synthesizer. Most announcements are in CW, and the speech board is used very sparingly. The audio delay module removes the squelch tail, and also mutes DTMF tones sent to the repeater.