EMRFD Message Archive 9001

Message	Date	From	Subject
9001	2013-08-21 14:56:43	Peter Parker	Wideband RF phase shift circuit
Wonder if anyone's tried this: http://www.seekic.com/circuit_diagram/Control_Circuit/3_30_MHz_QUADRATURE_PHASE_SHIFT.html Wide-band passive AF phaseshift network makes direct-conversion SSB generation possible Bridge networks each provide 45°phase shift, to give differential phase shift of 90°over entire frequency range with maximum phase error of about 1° Overall loss of network is about 6 dB,T1,T2,and T3 are wound on Neosid 1050-1-F14 of Indiana General F684-1 balun core. Twist together three 7-inch lengths of No. 26 enamel and wind 3 turns through the two holes. Connect two wires in series for 200-ohm windings. Article gives data for winding all other coils.-R. Harrison, A Review of SSB Phasing Teqhniques, Ham Radio, Jan. 1978, p 52-62. There are many adjustments but with modern equipment this should be easier than it was. 73, Peter VK3YE
9002	2013-08-21 19:08:09	kb1gmx	Re: Wideband RF phase shift circuit
9003	2013-08-21 19:31:03	Dave	Re: Wideband RF phase shift circuit
ECL flip flops are not extinct. In my UHFSDR, I use 2 SY10EP52 following a grade A (3.5 to 1400 MHz) LVPECL Si570. The LVPECL flip flops are guaranteed to a min of 4 GHz! Price is under $4 each. The LVPECL Si570 has 2 180 deg. outputs, so 2 of the SY10EP52's will generate I and Q LO at 1.75 to 700 MHz. With PowerSDR and NO hardware adjustments, I can't see the opposite sideband at 432 MHz. The LVPECL outputs directly drive a ADE-2ASK DBM through a 3 dB pad. Dave - WB6DHW <http://wb6dhw.com>
9004	2013-08-22 01:48:30	Ashhar Farhan	Re: Wideband RF phase shift circuit
It promises 1 degree error. That's quite a lot in phasing systems. You can acheive far more for possibly less with a single 74AC74. - farhan
9005	2013-08-22 15:04:21	kb1gmx	Re: Wideband RF phase shift circuit
9006	2013-08-22 15:12:35	kb1gmx	Re: Wideband RF phase shift circuit
Farhan, Yes, you understand. Old (slow) parts VS modern and much faster parts. Even at that the RC network was limited in the same range. The significance of the article was that it was a indicator of what could be done and even the article suggested that better parts on the horizon could significantly improve matters. An example of that was Tayloe's design with a QSD mixer driven digitally and feeding opamp based allpass phase shifter. That produced a receiver that is a stellar performer. Allison