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Homebrew RX
I had posted this elsewhere, and it has created some interesting feedback.
Based on Wes W7ZOI's Preogressive RX from the late 1980's. A wonderfully balanced design to which I added some bells and whistles I like in a receiver. These are some shots of my almost finished 1980's theme HF receiver. All stainless hardware, teflon wiring. Rock stable VFO, homebrew xtal filters ( 5/2/5/0.5), selectable and defeatable AGC, notch filter, tone control, QSK input,built in front end BP filters for each band, preselector, AM/USB/LSB/CW. Enjoy: http://www.parelectronics.com/pics/W7ZOI11%20copy.jpg http://www.parelectronics.com/pics/w7zoi13jpg.jpg http://www.parelectronics.com/pics/w7zoi14.jpg http://www.parelectronics.com/pics/w7zoi15.jpg Dale W4OP for PAR Electronics, Inc. |
VERY nice work, Dale. Makes me want to build a receiver again!
73, Floyd - K8AC "Dale Parfitt" wrote in message news:FNl0e.16399$b_6.6287@trnddc01... I had posted this elsewhere, and it has created some interesting feedback. Based on Wes W7ZOI's Preogressive RX from the late 1980's. A wonderfully balanced design to which I added some bells and whistles I like in a receiver. These are some shots of my almost finished 1980's theme HF receiver. All stainless hardware, teflon wiring. Rock stable VFO, homebrew xtal filters ( 5/2/5/0.5), selectable and defeatable AGC, notch filter, tone control, QSK input,built in front end BP filters for each band, preselector, AM/USB/LSB/CW. Enjoy: http://www.parelectronics.com/pics/W7ZOI11%20copy.jpg http://www.parelectronics.com/pics/w7zoi13jpg.jpg http://www.parelectronics.com/pics/w7zoi14.jpg http://www.parelectronics.com/pics/w7zoi15.jpg Dale W4OP for PAR Electronics, Inc. |
"Dale Parfitt" wrote in message
news:FNl0e.16399$b_6.6287@trnddc01... I had posted this elsewhere, and it has created some interesting feedback. Based on Wes W7ZOI's Progressive RX from the late 1980's. A wonderfully balanced design to which I added some bells and whistles I like in a receiver. These are some shots of my almost finished 1980's theme HF receiver. All stainless hardware, teflon wiring. Rock stable VFO, homebrew xtal filters ( 5/2/5/0.5), selectable and defeatable AGC, notch filter, tone control, QSK input,built in front end BP filters for each band, preselector, AM/USB/LSB/CW. Enjoy: http://www.parelectronics.com/pics/W7ZOI11%20copy.jpg http://www.parelectronics.com/pics/w7zoi13jpg.jpg http://www.parelectronics.com/pics/w7zoi14.jpg http://www.parelectronics.com/pics/w7zoi15.jpg Dale W4OP for PAR Electronics, Inc. Dale - Very nice. Looks like you built the RX .. that I am still designing since 1980 and reading Wes' articles. :-) I see you used a 9 MHz IF. Any particular reason that you used separate (LO) oscillators for each band (rather than a single oscillator with switchable crystals) ? The cabinet look a bit like some LMB enclosures. Greg w9gb |
"gb" wrote in message ... "Dale Parfitt" wrote in message news:FNl0e.16399$b_6.6287@trnddc01... I had posted this elsewhere, and it has created some interesting feedback. Based on Wes W7ZOI's Progressive RX from the late 1980's. A wonderfully balanced design to which I added some bells and whistles I like in a receiver. These are some shots of my almost finished 1980's theme HF receiver. All stainless hardware, teflon wiring. Rock stable VFO, homebrew xtal filters ( 5/2/5/0.5), selectable and defeatable AGC, notch filter, tone control, QSK input,built in front end BP filters for each band, preselector, AM/USB/LSB/CW. Enjoy: http://www.parelectronics.com/pics/W7ZOI11%20copy.jpg http://www.parelectronics.com/pics/w7zoi13jpg.jpg http://www.parelectronics.com/pics/w7zoi14.jpg http://www.parelectronics.com/pics/w7zoi15.jpg Dale W4OP for PAR Electronics, Inc. Dale - Very nice. Looks like you built the RX .. that I am still designing since 1980 and reading Wes' articles. :-) I see you used a 9 MHz IF. Any particular reason that you used separate (LO) oscillators for each band (rather than a single oscillator with switchable crystals) ? The cabinet look a bit like some LMB enclosures. Greg w9gb Hi Greg, I did not deviate a lot from Wes's original PR design- and that used a 9 MHz IF. I also had a bunch of xtals for the filters- so just stuck with it. It also allowed the 49M LO to double as the 160M L.O. F.A.R. circuits had the L.O. boards already made up, so I went with that. No reason I suppose, if one had an osc. that would paly well over the entire range w/ good spectral purity that a single L.O. and PIN diodes could not be used for switching. Would have saved on some SMA connex! The side rails and cabinet, and matching speaker cabinet (not shown) are from a junker SB-303 I found on E Bay ( have another for the mating TX once I recover). All the rest- front panel, subchassis, rear panel awere done in my machine shop. I know of the LMB you are talking about - nice stuff, but hard to come by in larger sizes these days I suppose. They were steel I thnk, whereas the Heath stuff is aluminum which I find a lot easier to machine. Dale W4OP |
Very nice indeed! What's the story behind the dial?
73, Mike, KK6GM |
"Mike Silva" wrote in message oups.com... Very nice indeed! What's the story behind the dial? 73, Mike, KK6GM Hi Mike, The dial was the original inspiration for the receiver- it is an Eddystone 898 slide rule dial. 88:1 reduction, flywheel weighted and backlash free silky smooth. Dale W4OP |
Dale
Very, very, very, nice job, thanks for showing your work.. I like the room inside to work on it.. The workmanship is commercial grade, what is your profession? Did yiu say you've laced it, if so how about a pix? The only thing that I see that I would do if I were building it is I would swap the tone and volume as I like the volume right next to the tuning knob. Where does one get an eddystone dial these days and how much? -- 73 Hank WD5JFR "Dale Parfitt" wrote in message news:FNl0e.16399$b_6.6287@trnddc01... I had posted this elsewhere, and it has created some interesting feedback. Based on Wes W7ZOI's Preogressive RX from the late 1980's. A wonderfully balanced design to which I added some bells and whistles I like in a receiver. These are some shots of my almost finished 1980's theme HF receiver. All stainless hardware, teflon wiring. Rock stable VFO, homebrew xtal filters ( 5/2/5/0.5), selectable and defeatable AGC, notch filter, tone control, QSK input,built in front end BP filters for each band, preselector, AM/USB/LSB/CW. Enjoy: http://www.parelectronics.com/pics/W7ZOI11%20copy.jpg http://www.parelectronics.com/pics/w7zoi13jpg.jpg http://www.parelectronics.com/pics/w7zoi14.jpg http://www.parelectronics.com/pics/w7zoi15.jpg Dale W4OP for PAR Electronics, Inc. |
"Henry Kolesnik" wrote in message m... Dale Very, very, very, nice job, thanks for showing your work.. I like the room inside to work on it.. The workmanship is commercial grade, what is your profession? Did yiu say you've laced it, if so how about a pix? The only thing that I see that I would do if I were building it is I would swap the tone and volume as I like the volume right next to the tuning knob. Where does one get an eddystone dial these days and how much? -- 73 Hank WD5JFR Hi Hank, There are a few things I would do differently too- unfortunately, that front panel has too many hours in it ( for me at least) to change. I learn on each one. I found the Eddystone on EBay and looking for another for the matching TX. My professon is EE, but have a full machine shop and just enough knowledge to use the mill and lathe. Dale |
"gb" ) writes: I see you used a 9 MHz IF. Any particular reason that you used separate (LO) oscillators for each band (rather than a single oscillator with switchable crystals) ? Surely because it works out to be simpler. People often make the mistake that extra circuitry is bad because it complicates things, but the reality is often that extra circuitry simplifies things. Back in the days of tubes, their bulk and filament current (or slow startup if you switch the filament) meant that one did give thought before adding another tube. It probably was simpler to switch crystals than switch oscillators, and compared to the cost of tubes and sockets, the switch was relatively cheap. Once transistors came along, their size, low current and instant on meant the game changed. If adding another transistor in an IF stage meant that all the stages were running at a lower level, better to do. It added little to the cost, and pretty much nothing to the current drain. If you switch crystals, you limit layout. You need that switch near the crystals (and in some cases may need two poles per position), or you need to use relays (I've seen it done in mods to tube equipment) or diode switches. Those diodes can often cause some problems, depending on choice and useage. Switching crystal oscillators means none of this applies, and the cost of the transistor and passive components is nothing compared to the cost of the crystal. This is a theme of some of Hayward's work. Various times, he's described transceivers, and not only is he using separate IF strips for receive and transmit, but he's got a separate IF filter for each function. His reasoning is that it makes the chain cleaner by not having the switching. Given the cost of commercial filters, I'm not sure that's the best choice, but certainly there is a tradeoff. If adding a few dollars for an extra RF stage rather than switching tuned circuits requires a cheaper switch, or makes it easier to do the switching, it may be worth spending those few dollars rather than fuss too much. Jerry Vogt (I"ve spelled that wrong) who seemed to be connected with Hamtronics (at least, he wrote about their stuff for Ham Radio magazine) pointed out in an article about preamps that a manufacturer needs to cut costs. They skimp on parts because any single part saved is multiplied by the number of units built. But a hobbyist building a single unit doesn't have that multiplier. If they toss in an extra bypass capacitor here, or build each stage into a metal box for shielding, the cost is right there. They don't have to worry about 10,000 more capacitors, or whatever. Michael VE2BVW |
Cool stuff. Way cool.
Just trying to sort out the bandswitching from the pictures: Antenna input is switched to one of six bandpass+optional RF amp boards. It looks like the antenna switching is by the black relays in the back? Eight bands, six band boards, a couple of the bands must be close enough together that they utilize a common board? Or maybe the IF *is* one of the bands... There appears to be a preselector knob on the front, how does this go into the bandpass/RF amp boards. The output from the RF band boards is then brought to some sort of combiner board that I cannot make out anything but a bunch of SMA jacks on. Is there switching there too, or (because of power switching to the RF boards) is this just a simple combiner? And that Eddystone dial is to die for. Oh, man. Tim. |
"Tim Shoppa" wrote in message oups.com... Cool stuff. Way cool. Just trying to sort out the bandswitching from the pictures: Antenna input is switched to one of six bandpass+optional RF amp boards. It looks like the antenna switching is by the black relays in the back? Eight bands, six band boards, a couple of the bands must be close enough together that they utilize a common board? Or maybe the IF *is* one of the bands... There appears to be a preselector knob on the front, how does this go into the bandpass/RF amp boards. The output from the RF band boards is then brought to some sort of combiner board that I cannot make out anything but a bunch of SMA jacks on. Is there switching there too, or (because of power switching to the RF boards) is this just a simple combiner? And that Eddystone dial is to die for. Oh, man. Tim. Hi Tim, An excellent job of sleuthing- I never could have done that.The RX is essentially an 80M RX with xtal controlled converters for the other bands. You are correct, the rear board switches the antenna to one of 6 front end BP+LP filters- 10M 28-28.5 and 28.5-29 share a filter and 80M is bypassed through this section directly into the preselector (which works on 3.5-4MHz only). The board along the power supply side switches the filter outputs into the 1st mixer. A relay on the output of the 1st mixer selects either its output ( 3.5- 4MHz) or the 80M signal directly from the antenna. This signal then goes to the preselector- which is a very sharp tunable BP. The relay board on top of the chassis toward the rear selects the appropriate L.O. and routes B+ through the coax to the L.O. 160M and 49M share the same L.O. but different input filters. Again, brilliant work on your part. Dale W4OP |
That's very well said!
The "optimum" design is, as you say, very much a matter of the particular situation. In my career doing circuit design, I've worked for a company where products were custom or nearly custom -- a production run of 10 was a big deal. In that situation, if I could save half an hour of design time by using a $20 part instead of a $5 part, it was a very good trade. I've also designed a product for a mass near-consumer market. There, a week of extra work spent in getting a few pennies out of the production cost was worthwhile. We all have to remember that: 1. There's no one best way for everybody, every project, or every market or situation. 2. What's best for the mass manufacturers, or for that matter another homebrewer, isn't necessarily the best for us. 3. The best way to do a design is constantly changing, as both techology and our own situations (e.g., the amount of time and money we have) keep changing. Design is a creative process, and there's a lot of art as well as skill in it. Finding a better way to do something requires both, and knowing the appropriate time to declare it "good enough" requires art, skill, and discipline too. Roy Lewallen, W7EL Michael Black wrote: "gb" ) writes: I see you used a 9 MHz IF. Any particular reason that you used separate (LO) oscillators for each band (rather than a single oscillator with switchable crystals) ? Surely because it works out to be simpler. People often make the mistake that extra circuitry is bad because it complicates things, but the reality is often that extra circuitry simplifies things. Back in the days of tubes, their bulk and filament current (or slow startup if you switch the filament) meant that one did give thought before adding another tube. It probably was simpler to switch crystals than switch oscillators, and compared to the cost of tubes and sockets, the switch was relatively cheap. Once transistors came along, their size, low current and instant on meant the game changed. If adding another transistor in an IF stage meant that all the stages were running at a lower level, better to do. It added little to the cost, and pretty much nothing to the current drain. If you switch crystals, you limit layout. You need that switch near the crystals (and in some cases may need two poles per position), or you need to use relays (I've seen it done in mods to tube equipment) or diode switches. Those diodes can often cause some problems, depending on choice and useage. Switching crystal oscillators means none of this applies, and the cost of the transistor and passive components is nothing compared to the cost of the crystal. This is a theme of some of Hayward's work. Various times, he's described transceivers, and not only is he using separate IF strips for receive and transmit, but he's got a separate IF filter for each function. His reasoning is that it makes the chain cleaner by not having the switching. Given the cost of commercial filters, I'm not sure that's the best choice, but certainly there is a tradeoff. If adding a few dollars for an extra RF stage rather than switching tuned circuits requires a cheaper switch, or makes it easier to do the switching, it may be worth spending those few dollars rather than fuss too much. Jerry Vogt (I"ve spelled that wrong) who seemed to be connected with Hamtronics (at least, he wrote about their stuff for Ham Radio magazine) pointed out in an article about preamps that a manufacturer needs to cut costs. They skimp on parts because any single part saved is multiplied by the number of units built. But a hobbyist building a single unit doesn't have that multiplier. If they toss in an extra bypass capacitor here, or build each stage into a metal box for shielding, the cost is right there. They don't have to worry about 10,000 more capacitors, or whatever. Michael VE2BVW |
Dale, that receiver is among the best homebrew rigs that I have seen
in 45 years! Incredible job! Ted KX4OM On Wed, 23 Mar 2005 22:08:37 GMT, "Dale Parfitt" wrote: I had posted this elsewhere, and it has created some interesting feedback. Based on Wes W7ZOI's Preogressive RX from the late 1980's. A wonderfully balanced design to which I added some bells and whistles I like in a receiver. These are some shots of my almost finished 1980's theme HF receiver. All stainless hardware, teflon wiring. Rock stable VFO, homebrew xtal filters ( 5/2/5/0.5), selectable and defeatable AGC, notch filter, tone control, QSK input,built in front end BP filters for each band, preselector, AM/USB/LSB/CW. Enjoy: http://www.parelectronics.com/pics/W7ZOI11%20copy.jpg http://www.parelectronics.com/pics/w7zoi13jpg.jpg http://www.parelectronics.com/pics/w7zoi14.jpg http://www.parelectronics.com/pics/w7zoi15.jpg Dale W4OP for PAR Electronics, Inc. |
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