It's hard to believe that the engineer has looked at the scale ... If such a characteristic would be standard I would not recommend the YAESU FT-450 to be used for medium or wider digital modes like Olivia etc.
I remember that first tests of the FT-450 complained about poor tx audio performance, but I don't remember the modification on later versions. As it looks my radio (bought in August 2007 in Europe) performs better in combination with the soundcard I have. 73 Juergen, DL8LE --- In digitalradio@yahoogroups.com, Sholto Fisher <sho...@...> wrote: > > Juergen, > > Thanks for doing the test. > > Now I am confused because I contacted Yaesu and sent them this graph of > my measured transmit passband: > > http://www.projectsandparts.com/misc/ft-450tx.gif > > And this is what the engineer told me: > > "Your graph shows the typical audio roll off expected. The bass band > deviation for the FT-450 is 300-2500. You would expect the dBWs to peak > as the filter narrows and conversely to drop off sharply as you approach > the band edges. That is exactly what your data shows. Your FT-450 is > performing within design parameters." > > I agree with your comments regarding the sound card & interface roll off > and I will measure this later today with an oscilloscope. But from > experience this sound card (audigy 2) and i/f has been in use with my > old FT-897D and I did not observe such a problem. > > I am quite prepared to believe it is something I am doing wrong but I > will need to take more measurements to find out where the error is (if > there is one). > > 73 Sholto. > KE7HPV > > > > dl8le wrote: > > > > > > I did a quick test only yesterday night at my FT-450 and here are the > > results: > > > > 500 Hz 40 W > > 1000 Hz 40-50 W > > 1500 Hz 40 W > > 2000 Hz 40 - 50 W > > 2500 Hz 20 W > > > > There is not at all such a big difference for the different tones even > > though it's for sure not a very even passband for the system soundcard > > + transceiver. I have to say, however, that I didn't do any precise > > measuring of the output voltage of the soundcard. This means that it > > is not correct to make any conclusion to the transceiver passband > > based on the above figures. > > > > 73 > > > > Juergen, DL8LE > > > > --- In digitalradio@ yahoogroups. com > > <mailto:digitalradio%40yahoogroups.com>, Sholto Fisher <sholto@> wrote: > > > > > > Hi all, > > > > > > I picked up a new Yaesu FT-450 over Xmas and have discovered that the > > > transmit passband seems very uneven to me. Using the same settings, > > i.e. > > > audio drive, USB DATA mode, constant RF POWER selection - a single tone > > > from the soundcard at 500Hz could produce 20W, a tone at 1000Hz 7W, a > > > tone at 1500Hz produces only 3W output and at 2000Hz it is down to 1.8W. > > > > > > The interface is a Signalink SL-1+ and I know it works fine because I > > > have used this same interface (and soundcard) with an FT-897D for years > > > without problem. > > > > > > Has anyone else got an FT-450 on this group and could do a similar test > > > to see whether it is just my rig that has the problem or it is these > > > radios in general? The firmware in mine is 0194. > > > > > > Power out in CW mode is 100W without difficulty. > > > > > > I suppose using PSK31 the problem is not severe but wide bandwidth > > modes > > > like ALE or MT63 e.t.c., could be a real problem. > > > > > > Other than this the FT-450 seems a very nice little rig and at $616 > > from > > > AES was too good to resist. The RX is very nice but you need to play > > > with the DSP a bit to get the most out of it. Surprisingly (at least to > > > me) it is superb on AM SWL broadcast too. > > > > > > Thanks es 73, > > > > > > Sholto > > > KE7HPV > > > > > > > >
