Hello Chris, I saw your design some times ago and congratulation for you design and big job to finish equipment. I am R&D engineer and for me it is very hard that is something finished HI!!!
I made a lot of experiments and design in CAD to see influence of this VCC/2 voltage. My conclusions are that S/H will work even that is not biased (I tested this practically). Problem is if you use as classic demodulator IMD higher order 5,7... will be very high for high input level. I have some design classic DC receiver better dynamic than famous R2 and RX super heterodyne type with 74HC4066 If I find time I shall publish it because it can be interested for some designers. Insertion loss in that design is not too sensitive to exactly VCC/2 but you will have a loss in dynamic range if output signal are not around half VCC. 4053 .4066 are CMOS IC but problem is that in this use with big R in divider Vcc/2 10K or even 2k2 we haven't VCC/2. I am using in all new design 1K. I designed and tested as dead bug construction also real new type of VHF (50 ,144 432,1280 MHz) S/H RX with outstanding performances extra simple and without 2 (twice)or 4 times higher LO. I hope that I shall find some free time to write article for QEX. This RX is much,much simpler than DSP10, or RX from SM5BSZ or S53MV but performances is hard to believe that coming from few extra cheap components. there is no classic 1 dB compression . Demodulators are working even with input signal higher than LO linear . What is your experience with VCC/2? I wish you successfully SDR design and I hope that we shall stay in touch. VY 73/72 Tasa YU1LM/QRP Original Message ----- From: "Chris Hirt" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Thursday, July 27, 2006 1:06 PM Subject: [soft_radio] Re: 4 new HF SDR designs from YU1LM/QRP > Dear Mr. Tasic-Tasa > > I look at http://www.qsl.net/yu1lm/homebrew.htm. Great!! > Thanks for puplishing Your fantastic job of Your SDR experiments with > 4066 and 4053 switches (my own QSD experiments are at > http://home.pages.at/chirt/HDR2005.htm.) > > Mostly of the homebrew SDR receivers have a bias voltage 1/2 of the > Vcc. In Your ADTRX1 You also divide +5V / 2 = 2,5 V. Do You test other > bias voltages or is this bias the best for the 74HC4053 ? My own > experiments shows a great performance sensitivity dependent of this > voltage. > > 73 > Chris > > > > --- In [email protected], "Tasic Sinisa" <[EMAIL PROTECTED]> wrote: >> >> Hello SDR OMs, >> >> I uploaded 4 new SDR designs. All 4 new designs are based on use > 74HC4053 IC >> as S/H (sample and hold ) element in demodulators , modulator and >> transceiver. >> >> 1. SDR HF I/Q S/H (Sample and Hold) Receiver-DR3X from 30 kHz-35 MHz > for 3 >> bands harmonically related with 1(one) oscillator or 1 XTAL >> >> 2.SDR HF I/Q S/H (Sample and Hold) Receiver - DR2B from 30 kHz- 35 > MHz >> with external LO (local oscillator) >> >> 3.SDR HF I/Q S/H (Sample and Hold) Mono band Receiver - DR2C from 30 > kHz- 50 >> MHz with LO (local oscillator) at receiving frequency >> >> 4. Low power SDR HF I/Q S/H (Sample and Hold) transceiver- ADTRX1 > from 30 >> kHz-35 MHz with external LO- part1 >> >> VY 73/72 and GL in SDR homebrew Tasa YU1LM/QRP >> >> www.qsl.net/yu1lm >> > > > > > > > > > > Yahoo! Groups Links > > > > > Yahoo! Groups Links <*> To visit your group on the web, go to: http://groups.yahoo.com/group/soft_radio/ <*> To unsubscribe from this group, send an email to: [EMAIL PROTECTED] <*> Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
