![]() K6. JRF Home Page. W2. ONV became a SK on Aug 1. His disease became aggressive and quickly. A sad day for all Ham Radio. Bill had been . He'd reply that when he got to ! One of my problems, was simply that I couldn't hear. His radio transmitted 5. Khz, so that's why it was a mystery. The Spectra Plus chart captures the essence of Bill's SSB audio. Many. don't know this but it was Bill that charged me to make an . Yes, it was he that got. About a 6 - 7 months later, the new FT1. D ESSB radio was born. He would mention. He was so proud that it was done and a member of the 'group' did it. I left active ham radio in 2. I removed all of my antennas so I. I wanted . It delayed me for. I got over his demise. When I was setting up the . It was well. marked meaning it had made the 'rounds'. Follow the links in the table to read reviews. You can also add a new product or service in the Ham Software - Other than logging category. K6JRF's Page formerly W6FZC FM-DX Tuner and FM Yagi Design Photos by K6JRF. Ref ID# Antenna? Hungarian Amateur Radio Station NAME: Gyula Nagy, QTH: Szentes, QTH-LOC: KN06DQ, (84 m asl.) E-mail: [email protected] My Mirror Site in the QSL.NET. Update: Jun 14, 2014 = FTdx1200 & FTdx3000 4Khz SSB TX = Over the past few days, I spent some time critically looking over the specs of the FTdx1200 and FTdx3000 and. Yagi Optimizer is an old DOS program made more than 20 years ago by K6STI made to analyze and design antennas. It’s very suitable to VHF antenna modelling and. The BB drive. . Nothing against Aphex (and Behringer, etc) but the BB circuit was a 'joke' . Check out Bill's Memorial Page. Treble Audio Rolloff Discussion. Testing has reported that the Sony XDR FM Tuner experiences treble rolloff from the Pre. Amp Ckt and is anywhere from - 1. B @ 1. 5Khz. Every Sony tuner is somewhat different but measurements show that they all seem to fall into this defined attenuation range. Before. actually digging into this problem, I simply removed the four (4) caps no matter what treble loss they contributed. Tuners with circuit failures certainly would exhibit more. I employed a K6. STI chart that showed the treble rolloff of his Sony XDR tuner of - 2. B @ 1. 5Khz. After receiving a. I decided to use my own charts. There's a. lesson here, don't you think?? Spice preamp ckt simulation showed - 0. Khz and - 0. 8. 9db @ 2. Khz. Since Spice is never wrong. DSP Tuner module. In other words. the Preamp contributes - 0. B @ 1. 5Khz and the DSP Tuner + preamp totals to - 2. XDRguy's site shows a . He also has reported 0. B rolloff variations @ 1. Khz with different Sony XDR tuners. XDRguy measurement of the Sony XDR Treble Rolloff . The chart at the beginning of this section. However, I believe that the loss is not all from the Preamp ckt itself. If it's incomplete, so are the results! When the correct transistor. Also, I suspected that the. DSP Tuner's output impedance wasn't correct. The simulation results now shadow ? Doing many Spice simulations, I found that 3. B loss @ 1. 5Khz. Not a feasible answer to the problem. Another idea was a . One clue to this idea, is. C1. 2 and C2. 2, the attenuation drops to fractions of a . However, the theory was. C2. 1, C2. 2, C1. C2. 1 show values close to nominal. One final argument concerns the output impedance of the DSP Tuner Unit. Finding the impedance that delivers half- power into. Pre. Amp ckt (as the DSP Tuner's . Using Spice, the output impedance . And this value gives a good fit to measured results. All Spice simulations were re- run. This new value has changed some of the. In. general, all steady state AC frequency measurements have changed along with the recommended cap values. This relatively. high impedance plus the four caps . In order to be complete, I've. MUTE ckt into the schematic so that the . The R- C ckt forms a low pass filter which. V power- line from other ckts using this voltage. The Rrchn resistor represents the DC current drawn by the RIGHT channel preamp, apx. In previous analysis I hadn't included both the LPF and Rrchn. Since both effect the operating DC BIAS. LEFT channel, these ckt components s/b included. The new DC bias values are shown in blue next to the ckt. Note that there's no change to the . Results show - 2. B @ 1. 5Khz with nominal values for all circuit components. So, in summary, the observed Pre. Amp ckt treble loss has variation from different authors ranging from. B to - 2. 5db. But. Sony XDR FM Tuner's Pre. Amp Ckt. Total Harmonic Distortion ! The original analysis used a . After finding a correct. At low signal levels (0. Vpk), the preamp's THD performance is quite good but. THD rises with higher signal levels. It also begins to rolloff starting at 5. Khz so this action lowers the THD but also causes excessive treble rolloff as you saw. To 'tame' the LPF network, remove the two (2) capacitors (LEFT channel) and that reverses the treble rolloff. The THD results is shown. This. is due to the limited overhead operating range. The operating DC bias numbers in blue are shown in the. However, after doing a visual inspection, it is not that easy. SMD manufactured board. However, adding Negative Feed. Back (NFB) to this ckt dramatically lowers THD by forcing the ckt to operate in its. This is a small price for such a large performance improvement. The schematic shows the NFB resistor as Rnfb = 3. K as this is the . The. NFB resistor reduces the internal preamp's THD by forcing it to operate in its limited linear range. Looking at the THD chart above in the. The added cap is . Details in the . The BR is - 0. B with NFB resistor, Rnfb = 2. K. Their experience is to BUY tuners, listen and get together to . Note that they haven't actually MEASURED THD so everything is strictly qualitative! This process relies on the ears. With different venues, equipment and ! However, this process can be fine if they realize their lack of quantitative analysis. Sadly, they don't and make statements. FM tuners with medium to high THD levels sound better than a low THD tuner. This is simply ridiculous. An FM Tuner is. ALWAYS designed for low THD as is possible within the ckt's constraints. It is LOW THD that makes a FM tuner become an. For the non- technical, this is the ability to reproduce a ! Want Lowest THD . For me, I want the absolute lowest THD possible with the Sony. XDR preamp. To that end, making the NFB resistor. Rnfb = 2. 0K gives the lowest THD even for input signals (from the TU1 DSP unit) greater than 1. Vpk. In fact the. DSP Tuner's output level = 1. Vpk! The chart shows the response at various signal levels. Note the THD @ 0. Vpk is under 0. 0. Vpk and 0. 0. 5% at 1. Vpk. These are excellent numbers for basically. SC3. 05. 2) followed by an emitter follower (2. SC3. 05. 2) output with both operating on limited, single voltage. THD is normally expressed in percent but technical people get a greater . THD is defined as the ratio of the rms voltage of the harmonics to that of the fundamental component. This is measured by using a. The level is divided by the fundamental level. The distortion of an audio device indicates the extent to which a sinusoidal test tone signal is modified by non- linear. That means the. distortion level is more than 2. So if the room's sound pressure level is 1. W, the. distortion level is 5 milliwatts! At a . The distortion product is more. For the 1. 0W example, the distortion is 5. Do you honestly think that you can hear these distortion products?? The stock preamp has 1. For my audio. system, the gain loss makes the other equipment's output balance out perfectly and I have a lot of ! It is inversely proportional to the value. NFB resistor; 6. 8K = - 0. B; 2. 0K = - 0. 7d. B. This removes the bass rolloff and flattens the response to - 0. With NFB, the output is. THD = 0. 0. 38%. Not too shabby! With the 2. 0K NFB resistor installed, your Sony. XDR tuner's preamp WILL NEVER. CLIP on the strongest INPUT signal and will recover audio that has the range of 0. THD ! Note also no delay time .
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |