Some of the Yaesu dual-band mobiles have no filtering in the audio chain. They tout the fact that the audio is very "hi-fi" sounding. In fact, almost anything from 50 Hz to 10 kHz will make it through the MIC audio circuit. After that, they mix in the CTCSS. I have one user on my repeater that drives GM vehicles, and for some reason, the tire noise at certain speeds comes through the microphone and beats with the CTCSS tone. He drops out like crazy and it frustrates us all. Several other Yaesu users got rid of their radios because they wouldn't work with Motorola repeater PL decoders. One cure was to turn deviation way up so the CTCSS came out at over 1 kHz deviation, but then the user had to remember to speak softer because the radio waw now capable of over 7 kHz deviation. Not the right way to go.
Many radios have bandpass or highpass filters in the MIC audio stages so the low frequency audio doesn't interfere with the CTCSS or DCS signals, but not Yaesu. So I'm not surprised that this "feature" is present in a lot of their products. Strangely, the Yaesu quad-band mobile radio doesn't suffer from this problem. I've had this problem using MSF5000 and MaxTrac receivers. I know both units are capable of decoding PL down to less than 100 Hz of deviation, and everything works fine with a Yaesu if you can key it up but not pass any MIC audio through the transmitter. Of course, while that's a fix, it's not what the users want. It'll be hard to convince all those people that their radios are the cause of the trouble, not the repeater. Bob M. ====== --- Eric Lemmon <[EMAIL PROTECTED]> wrote: > Al, > > Something doesn't sound right here... most Yaesu > portables- including my own > VX7- have far too much tone deviation as delivered. > This is common with > many Amateur-grade radios, and Alinco is the worst. > The CTCSS deviation is > usually not adjustable in the small portables, so > the manufacturers > apparently think that more is always better. > > I don't have experience with the VX6, but I would be > surprised if the CTCSS > deviation wasn't close to 900 Hz. Perhaps these > users modified all of the > radios to pad down the tone deviation, but I think > that 500 Hz is ideal. I > will check my Quantar service manuals at work for > confirmation, but I > suspect that the tone sensitivity is fixed. > > I wonder if there is another factor at work here, > such as the purity of tone > coming from the VX6 radios, and the tone accuracy. > Does the Quantar work > with other radio brands/models? Maybe it doesn't > like raspy tones. > > 73, Eric Lemmon WB6FLY > > > -----Original Message----- > From: Repeater-Builder@yahoogroups.com > [mailto:[EMAIL PROTECTED] On Behalf > Of Al Wolfe > Sent: Tuesday, September 25, 2007 9:24 PM > To: Repeater-Builder@yahoogroups.com > Subject: [Repeater-Builder] Quantar and PL > > We recently replaced an aging UHF machine with a > Quantar for a local ham > repeater. Now it seems that some users are not able > to key up the system. > Turns out their radios (all VX6's) have fairly low > tone deviation. Tests on > the Quantar show that it needs at least 300 htz to > key it. This seems > reasonable to me but the users all say "Well, my > radio used to work with the > > old repeater. So fix the new one." > > Is there a way to increase the sensitivity to PL > tones in a UHF Quantar? > Is this desirable? > > Al, K9SI > > > > > > > > Yahoo! Groups Links > > (Yahoo! ID required) > > mailto:[EMAIL PROTECTED] > > > ____________________________________________________________________________________ Be a better Heartthrob. Get better relationship answers from someone who knows. Yahoo! Answers - Check it out. http://answers.yahoo.com/dir/?link=list&sid=396545433
