Then tell the ARRL. Phase shift SSB was common in the '50s & '60s. There were numerous construction articles in QSL & the ARRL handbook.
-- You can't fix stupid. You can't even put a Band-Aid? on it, because it's Teflon coated.
The usual phasing method is a cheat--you make two all-pass networks whose phase _differs_ by about 90 degrees, and rely on the ear to be insensitive to slowish phase shifts. There's another cute network that's sort of a triple helix, to make three signals 120 degrees apart, but I forget what that one's for. You don't need it for SSB.
Cheers
Phil Hobbs
-- Dr Philip C D Hobbs Principal ElectroOptical Innovations 55 Orchard Rd Briarcliff Manor NY 10510 845-480-2058 email: hobbs (atsign) electrooptical (period) net http://electrooptical.net
Don't know why you consider it a "cheat". Two simple all-pass networks, one centered at [sqrt(2)-1]*fmid and the other at [sqrt(2)+1]*fmid] will yield a phase difference of 90° ± 2° over one octave.
Sid Darlington wrote a paper detailing design of such networks working over a larger range. I've misplaced my copy, which is why I recently posted, asking if anyone had a copy. ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Remember: Once you go over the hill, you pick up speed
k f
ft
A phase sequence filter?
George H.
They're not that hard to find yet; DigiKey and Mouser have many of them, and with companies like Murata are likely still selling millions per years the trick is just to find how to get some small quantities. Even 25 years from now, I expect they'll be readily available on eBay.
Conceivably, yes, although it might end up being a fair amount of work!
That sounds even less likely to me: It'd be difficult to find crystals with wide enough passbands, and the impedances typically involved will require matching networks that will likely be lossier than you'd like.
But to directly answer your question... Amidon will still sell you tunable inductor "cans" with the corresponding ferrite bits, and you might be able to wind your own transformer:
---Joel
Ah, so you've seen my proposal to get the feds to hand me millions of dollars to replace the air traffic controller radios from their current AM implementation to something all digital and highly proprietary then, yes?
:-)
For anyone who wants more details on the history here, check out this document:
Yes. In fact, Collins still sells them today, although they seem to do a pretty poor job advertising them. (Here's some mounted on a PCB:
Wikipedia has a nice article on them:
Terman's book is available on-line as a PDF, and I'd also point to the old RCA Radiotron Manual (also available as a PDF). Pete Millett's web site has a bunch of scans that are quite useful as well:
---Joel
Joerg expounded in news: snipped-for-privacy@mid.individual.net:
Actually, there is also the possibility of making a modern VFO in your otherwise retro radio.
Consider using an old stepper motor for the tuning control (more on that below) and obviously a nice LCD with large lettering for tuning frequency display. AVR or PIC behind that.
For the tuning control, I've always wanted to put a stepper motor operated as generator through a zero crossing detector (or better with hysterisis).
That way as you turn the stepper motor, with attached knob, into a precise tuning control. Each step produces a nice click pulse back to the microcontroller to move the local oscillator so many khz one way or tother.
Make the software smart enough to discern fast rotates (big steps) and slow turns as little steps in tuning.
For extra marks, add some favourite station buttons. :)
Warren
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
Is this it?
If not, maybe you can find it here. They have the complete run of BSTJ:
Howard
Yep, that's the one! Thanks!
Good link! Thanks, again! ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Remember: Once you go over the hill, you pick up speed
I have also seen some references to such module in ARRL handbooks and as far as I remember, the type number was in the general format XnXn (like R2D2), but if I remember correctly, the second X was "Q". Hopefully this might bring up some memories.
The opposite sideband rejection in a phasing SSB receiver depended very significantly on the (relative) accuracy of the phasing network in the I and Q paths.
While it is easy to get resistors with 1 % or even 0.1 % accuracy, getting capacitors with even 1 % accuracy is hard. In practice, one needs to buy a batch of capacitors and select pairs with equal (but not necessary nominal) capacitances, in order to get good opposite sideband rejection.
Look up Image Reject (or SSB) Mixers.
For the audio, ever here of pots ?:-) ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Remember: Once you go over the hill, you pick up speed
Crap! Make that "here", "hear" :-( ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Remember: Once you go over the hill, you pick up speed
For tubes (and high voltage FETs) the circuits are quite straight forward. For bipolar transistors with very low input and output impedances, you need to connect the transistor through some intermediate tap in the resonant circuit inductor.
It is quite trivial to generate a very narrow band filter by simply cascading multiple resonant circuits (neglecting any temperature effects) separated by an amplification device (tube/transistor).
However, in order to transfer some useful information, the modulated carrier also generates sidebands that must be transferred to the detector. For AM broadcast reception at least 4.5 (or 5 kHz depending on country) on both sides of the carrier needs to be passed to the detector.
At 455 kHz IF, one could either use staggered tuning (input resonant circuit tuned to 453 kHz, output tuned to 457 kHz) or use accurately controlled coupling/loading between two resonant circuits both tuned to 455 kHz, creating a double hump passband.
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
They have similar problems, though, in that very tight component matching is needed if you want to get much better than, say, 40dB image rejection. (There's a pretty picture here:
Not so. It's trivial to get LO's almost perfectly on 90°.
I've even done an on-chip version at 5.1GHz. ...Jim Thompson
--
| James E.Thompson, CTO | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC's and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
Remember: Once you go over the hill, you pick up speed
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
How "almost perfect" is it? :-)
If it's +/-1 degree, even with perfect amplitude matching, you'll never get better than 40dB image rejection with the standard mixer architecture there (and 40dB is certainly respectable, if not spectacular). One degree at 5.1GHz is about half a picosecond of jitter, so I suppose it starts to come down more to noise than component matching, at least insofar as generating the quadrature clocks go.
Here's one chip I've used:
Absolutely.
For image rejection mixers, in addition to the carrier 90 degree phase shift (which is trivial at least for a fixed carrier), but you also need the 90 degree phase shift across the base band frequency range, which, unfortunately can be hard, especially, if the relative frequency range is larger than 1:10 (e.g. 300 Hz .. 3 kHz).
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