Re: Frequency calibration
Charles W. Powell
Frank,toggle quoted messageShow quoted text
You may have to repeat the calibration several times to get the transmit frequency to match the specified frequency.. At least one of the units I built required a considerable amount of fiddling to get it right. If you have a frequency counter you should be able to get it spot on. If your counter doesn’t have a 50 ohm dummy load, I’d connect to a dummy load and then connect the counter to that either with clips or a “T” connection at the dummy load. The finals will withstand a little no-load abuse but I don’t recommend it.
If you do any programming, I’d also change the timeout from 5 seconds to 10 seconds. I did this on all the Hilltoppers I have built and it works fine, but I wouldn’t go more than 10 seconds. I changed mine because the Elecraft T1 wasn’t fast enough to tune in 5 seconds. The tuning timeout is set in the same part of the firmware.
Anyway, once you have the radio calibrated to the correct frequency (boot-up should be at 14060, I think) then set the receive offset using the fine trimmer cap. Default offset frequency is 800 Hz, which is the default pitch of the sidetone. This can be modified in firmware if you prefer something different, like 700 Hz or 600 Hz. Supposedly the bandpass is at 800 Hz but I have no trouble with any of my Hilltoppers at 600 Hz. If you modify the firmware, then it becomes necessary to recalibrate the receive offset, but it’s not necessary if you are happy at 800 Hz.
Does that all make sense to you?
Chas - NK8O