We’re already up to day 5 of operation for the 6m repeater. I’ve enjoyed meeting some new hams, and reconnecting with some old friends! Possibly this weekend some additional new users will arrive, as people have time to set up antennas, program their radios, and join in. If you haven’t tried it yet, I encourage you to drop in with your call sign and see who is around. If you’ve tried to get in and can’t, I’d like to know that too; e-mail me at firstname.lastname@example.org.
For a “new” repeater, constructed out of “old” parts, it is doing very well. A few minor adjustments have been made. First, the CW ID was too loud, so I dropped it down a little, and raised the pitch. I also lowered the level of the courtesy beep. Some radio and speaker combinations give a lot of boost to those frequencies, so this should help.
Second, each time I visit the repeater site, I turn the squelch knob just a smidge. You might think that you would want to adjust the squelch to be “right on the edge,” so that ANY signal can open it, and let the tone decoder weed out the noise. However, the tone decoder does an amazing job of sensing tone even when the signal is VERY noisy. It doesn’t do anyone any good to have the squelch opening on super-noisy signals. It annoys repeater listeners, and the person who transmitted the noisy signal hears a courtesy beep and thinks (falsely) that they can be heard on the repeater. I will keep adjusting the squelch VERRRRRRRY slowly until I reach the point where it generally blocks unreadable signals, and lets noisy but readable signals through.
Finally, I have been investigating the source of some intermittent noise, which is sometimes heard on received signals (that is, not during IDs, announcements, or hang time). On the very first day I noticed that wiggling the coax to the receiver input would make noise. It was actually two cables: a longer 1/4″ Heliax from the duplexer, which mated to a short pigtail that plugs into the receiver. Replacing the pigtail didn’t fix it, so made a single new cable that replaced both of the old ones. My impression is that it helped, but there may yet be more noise generators at work. We’ll have to see what happens on the first windy day, because ANY loose joint, or loose hardware ANYWHERE on the tower (even if not part of our antenna and feedline) could cause micro-arcing and RF noise generation. Grounding of the repeater is not complete either, so THAT might be a factor.
Someone suggested that a preamp might help with the weak signals. It might. I am sure I will try it at some point. My biggest concern with that is the VERY strong signals our antenna picks up from TV channels 24 and 25, and FM stations at 94.5 and 107.9. We do not have a bandpass filter, so a LOT of energy at those frequencies would reach the preamp and possibly overload it. I suppose I could ADD a bandpass filter at the cost of another 1 dB or so of signal prior to the preamp. We’ll put this on the list for future experimentation.
In the next post, I’ll get back to a discussion of the duplexer construction.