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Old 03-29-2011, 11:56 AM
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DaveInDenver DaveInDenver is offline
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Join Date: Jun 2006
Location: Larimer County
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Quote:
Originally Posted by nakman View Post
Ok here's a silly question, but if it doesn't do CTCSS does that mean no repeaters? simplex only?
If it does not do CTCSS, then yup. Some repeaters don't need CTCSS, but anymore that's pretty rare in the city.

Back when radios did not have tones or had optional tone boards, most repeaters did not use subtones because the spectrum was a lot less polluted. That was before cell phones, pagers, WiFi, plasma TVs, cordless phones, microwave ovens, microprocessor everywhere. It's all that stuff (mostly pagers) that prompted Motorola and GE to develop subtones for their commercial radios back in the 1970s and 1980s and it wasn't until the 1990s that ham repeaters really mushroomed with the use of tones, which is paralleled in the used VHF/UHF radios you see.

It's possible to add subtones outside the radio, several kits exist to do this. It's literally just a barely audible low frequency tone added to your signal, it's not really that exotic.

http://www.vk2bv.org/w_ctcss.htm
http://www.hamtronics.com/td5.htm

An experiment would be to record a tone and play it in the background when you talk. It would probably open the repeater if your mic was sensitive enough to such low frequencies (they probably aren't).
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