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#1
March 6th 08, 01:02 AM
posted to rec.radio.amateur.moderated
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And now for something totally different!
On Mar 5, 3:09�pm, Dave Heil wrote:
wrote: On Mar 3, 8:23pm, Dave Heil wrote: I find it impressive that Hallicrafters made so many different receiver models in so few years (say, 1945-1960). Loads and loads. �Most were variations on a common theme with styling changes though octal tubes might have been replaced by loctals or miniat ure 7 or 9 pin types. Hallicrafters never went for loctals in a big way; they were used only where there was no other choice at the time. Your variations-on-a- theme idea is correct; notice how similar the SX-42 and SX-62 are on the inside. The 'A-4 was the best of the period. �The models with the Collins vernier tuning knob were the best of the best. IMHO Collins made a design mistake by putting such a fast tuning rate (100 kc. per knob turn) on the 75A-4. The reduction knob fixed that. A few years ago, a small company began manufacturing a reduction knob for the 75A-4, machined out of solid brass. Functional and attractive. The 75A-4 is the first receiver I know of that included passband tuning as a standard feature. I think you're right. �My 75A-3 came with a Universal Service (predecessor to today's Universal Radio) PTO mod which plugs into the NBFM socket. �The Collins winged emblem was removed, a hole drilled in the spot and a long 1/4" shaft from the PBT box ran through the hole. An engraved plate was mounted on the panel and the shaft was fitted with a miniature knob. How did it provide PBT? The 75A-4 PBT is entirely mechanical; it works by rotating the PTO and the BFO controls simultaneously, but so that their frequencies move in opposite directions. The linearity of both oscillators is such that the received carrier frequency does not move. �A mod for the AGC time constant was also added. �The thing is nearly the equal to a 75A-4. NICE! That was followed by the light gray, low profile styling of the KWM-2/2A and S-Line in the late fifties. Which changed the game completely. Everybody began jumping on that band wagon. � Heathkit came up with the "poor man's S-Line"; Drake introduced the 1-A, 2-A and 2-B and TR-3; Swan introduced monoband and multiband transceivers; Hallicrafters and National also began producing smaller, lighter separates and transceivers. IIRC the 1-A predated the S-line and KWM-2. It was a revolutionary design; small, light and compact at a time when even inexpensive receivers were big and heavy. Note the tiny, taller-than-it-is-wide front panel and the very deep chassis. The 1-A had passband tuning too, but it was implemented by having a tunable LC filter at the last IF. The 2-A and 2-B are excellent receivers for their price and complexity, and are prized today. But they were a dead end in one way: there was no matching transmitter that could transceive with them. What the KWM-2 and S-line did was to make "transceiving" popular. The KWM-1 and a few other rigs like the legendary Cosmophone (the first true full-featured HF amateur transceiver) had been the first manufactured amateur HF rigs to use the same tunable oscillator to control both the transmitter and receiver, but they did not achieve wide popularity. Indeed, a homebrew 40 meter *CW* transceiver built around a surplus BC-453 was described in a 1954 QST, probably the first published use of the idea in amateur radio. It even had full QSK. But it was ahead of its time. The KWM-2 and S-line took transceiving to another level. Not only were they smaller and lighter than their predecessors, they had relatively few controls. They made SSB more popular with hams by reducing the cost and size and eliminating the job of zerobeating the transmitter. Tune an SSB station correctly and the transmitter was automatically on the right frequency. Add to this the grounded-grid linear amplifier and things really changed. High power 'phone became not only less expensive but a lot smaller and lighter. Transceivers and matched-pair separates became the new paradigm in HF ham gear; AM wasn't part of that. Compare the Heathkit line of 1964-65 with what they were selling just 5 years earlier for just one example. IMHO what turned the tide were two now-classic HF rigs: the Yaesu FT-101 and the Kenwood TS-520. I'd toss in the Yaesu tube-type rigs such as the FTDX-560 and 570. Well, sort of. They had QC problems and were really competition for the likes of Swan, who did the same lots-of-watts-from-sweep-tubes game. They did offer extras but you should look at the TS-520's receiver specs. �They're dismal. � But you have to ask "compared to what?" Plus they were almost all "solid state", which was a selling point even if performance suffered. Consider the TS-520S, for example. It did the usual 80-10 meter SSB job pretty well. But it also gave a choice of AGC fast/slow/off, an optional narrow CW filter that was pretty good, RIT/XIT, 160 meters and WWV/JJY, fan-cooled finals, plus a built-in AC power supply. Yep. �It served pretty well as an everyman's rig and would have been much better if the receiver section had been better design. Agreed, but for the time and price it was decent enough. Point is, it opened the door. �The Japanese were not the only ones with this problem. � Heath's early solid state receiver, the HW-303 was an absolute clunker in this regard. I think you mean the SB-303. And yes it was - very sensitive but at the cost of dynamic range. Hammarlund made one valiant effort to stave off the JA's with the introduction of the solid state HQ-215. �I have one of those and it is a pretty darned good receiver. �It has an edgewise drum dial with 1 KC readout, has fixed, selectable USB/LSB and a variable BFO for CW. �It has a preselector in the front end, offers AUX band positions and places for three Collins mechanical filters. �The mixing scheme is the same as the S-Line and it has the same 200 KC band segments. �There are input/output ports on the rear panel so that the receiver can be slaved to a 32S-whatever transmitter for transceive use. �I think it was first offered about 1967. Correct on all counts. It was meant to be a solid-state 75S-3. But never quite got there. Hallicrafters made the almost-all-solid-state FPM-300 transceiver a few years later, too. Its drum dial inspired the Southgate Type 4 (receiver) and Type 7 (transceiver) dials. But they use all-gear-drive. It should be remembered that there were some colossal also-rans in that period, too. B&W made their 6100 transmitter with its multiknob mixing synthesizer, obviously inspired by commercial/military sets like the R-1051. Stable but poorly adapted to amateur HF operation. The legendary Squires Sanders SS-1R was poised to give Collins a good run for the money, but without a matching transmitter, not many hams were going to spend S-line-level dollars for it. Some folks criticized amateurs for being "slow" to use solid-state HF rigs, but there was a reason for caution. More than one early SS rig had come to grief, like the Hallicrafters FPM-200 of the early 1960s and the EF Johnson Avenger transceiver, of which only about a dozen were made. Avenger was a decent rig but cost so much to make that EFJ never produced more, knowing they wouldn't sell. EFJ never again made an amateur HF transceiver, and was soon not making HF ham gear at all. Central Electronics pioneered the no-tune transmitter (with all tubes!) back in the late 1950s, and was poised to market a matching receiver (the 100-R) which was reportedly as good or better than the 75S-3. But the company was bought for some patents and other contracts and was soon out of the amateur market. The sole 100-R prototype survives to this day. OTOH, Southgate Radio is still building rigs after 40+ years... Not just price but price/performance/features combo. For example, try to think of a US-made HF amateur transceiver that had the following: - 100 watt output class - 6146 finals, not sweep tubes - Sharp CW filter - RIT/XIT - AGC off/slow/fast That's quite a number of preconditions. Not really, IMHO, and they're pretty basic things, easily implemented with 1960s technology. �I don't think there were any. Exactly. The Heath SB-102 comes close. � Not really. It doesn't have RIT/XIT, and you can't easily add it. Can't turn off the AGC nor adjust its time constant either. The Drake TR-4CW comes close (6JB6's). Only if you get the model that had both RIT and the sharp filter, which was only produced for a short time. Blink and you missed it. Plus check the price of a TR4-CW with power supply and speaker. Ouch! By comparison, the TS-520S had all of that and more, even if the rx wasn't as good. Digi-Key got its start about the same time as Ten Tec - 1968 or so. Their name comes from the fact that the company got started by selling digital ICs (RTL!) in small quantities to hams so they could build solid-state Morse Code keyers. Then they just kept growing, 'but the name stayed. They've done phenomenally well. �Many of the old line distributors are just plain gone. Newark and Allied are still around. Nor are they overly ornate. They are functional and attractive just as they are. Agreed. �I've often wondered if any of the modern gear will be functional/repairable in forty or fifty years. �My guess is that i t will not. I think it will be, but in different ways: The first way will be the renovators, who make a few good rigs from a pile of problem sets. This is already starting to happen; look on ebay for "TS-940" and you will see lots of parts for sale. The second way will be the rebuilders, who will make replacement PCBs using parts available then. A much harder go at first, but given the automation possibilities now, who knows what the future could do. Look up the stuff made by one of my Elmers, master homebrewer W2LYH. (several QST articles). I know a few guys who still operate the W6TC HBR series of receivers that they or others constructed. � There are folks still building HBRs today, from scratch. But with all due respect to those designs, do check out W2LYH's designs, such as the 23 tube receiver or the ultrastable Frankling VFO. His construction is an art in itself; no ornamentation needed. I often wonder what happened to his rig. I don't think I want to know. I also of quite a number of quality homebrew linear amps which are still put on the air on a regular basis. Yep. Also a number of SB-200s, SB-220s, L-4s and similar amps are pounding out the watts today, often with upgrades and modernizations. 73 de Jim, N2EY |
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#2
March 6th 08, 04:27 AM
posted to rec.radio.amateur.moderated
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And now for something totally different!
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#4
March 6th 08, 05:56 AM
posted to rec.radio.amateur.moderated
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And now for something totally different!
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#5
March 6th 08, 01:39 PM
posted to rec.radio.amateur.moderated
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And now for something totally different!
On Mar 6, 12:56Â am, Dave Heil wrote:
wrote: On Mar 5, 3:09�pm, Dave Heil wrote: wrote: On Mar 3, 8:23pm, Dave Heil wrote: A few years ago, a small company began manufacturing a reduction knob for the 75A-4, machined out of solid brass. Functional and attractive. I noted them when I saw the ads in Electric Radio.  The price was very dear. $125 IIRC. How did it provide PBT? I'm going to have to dig out the paperwork on the Universal Service unit (which I got copies of just a year or two back) and let you know. Will be good to know. The CW filter I have is the 800 Hz unit.  One of these days I may replace it with an Inrad unit.  I'll have to juggle things a bit to match the modern Collins mechanical filter to the radio. I think the same company that made the reduction knob made exact plug- in filters. Dunno if they made a CW one. At the University ham shack we had two 75S-3s. One had the 200 Hz filter, aka "the ringmaster". But boy could they hear! IIRC the 1-A predated the S-line and KWM-2. I think you'll find that all of them hit the market in '57. The KWM-2 came after the original S-line (75S-1/32S-1) Check your old QSTs, you'll see the 1-A advertised well before the KWM-2. It was a revolutionary design; small, light and compact at a time when even inexpensive receivers were big and heavy. Note the tiny, taller-than-it-is-wide front panel and the very deep chassis. Unfortunately it was built as an SSB-only receiver.  There were no provisions for a narrow filter for CW or a wider one for AM.  In fact, the BFO could not be turned off at all.  I sold a number of rig s after coming back stateside and the Drake 1-A was one of them. 1-A was Drake's entry into the ham receiver market; previously they had only made things like lowpass filters. Their idea was to cut the cost of SSB to the bone by making a receiver specific to the mode and leaving out anything not needed for SSB. Hence no diode detector, no BFO-off, no narrow filter, etc. But it had PBT, which also gave sideband selection, an S-meter and AGC that worked on SSB, and was very stable. That mode-specific thing inspired many of the Southgate receivers. The 2-A and 2-B are excellent receivers for their price and complexity, and are prized today. But they were a dead end in one way: there was no matching transmitter that could transceive with them. In the time when they were introduced, many folks were still using separates.  I've kept my 2-B because it really is a classic and performs well today.  The matching 2-BQ adds a lot to the receiver. About 15 years ago I walked away from a hamfest table that had a 2-B/2-BQ combo for $75. "To think about it". Oh fer dumb..... What the KWM-2 and S-line did was to make "transceiving" popular. Well, they made it popular for those with lots of money. Not just those folks. The idea got wide publicity and led to lots more rigs at a lot lower prices. If I recall correctly, there were identical-looking models with two different power output levels. Cosmophone 35 and Cosmophone 1000. Indeed, a homebrew 40 meter *CW* transceiver built around a surplus BC-453 was described in a 1954 QST, probably the first published use of the idea in amateur radio. It even had full QSK. But it was ahead of its time. You've aroused my curiosity.  I'll have to dig through the back issues and check it out.  There's a '453 lying about here somewhere. IIRC the author's last name was Deane. I do not know of any earlier HF amateur transceiver being described in QST or any other publication. The KWM-2 and S-line took transceiving to another level. Not only were they smaller and lighter than their predecessors, they had relatively few controls. They made SSB more popular with hams by reducing the cost and size and eliminating the job of zerobeating the transmitter. Tune an SSB station correctly and the transmitter was automatically on the right frequency. I have to disagree with the reduction of cost.  When the KWM-2 was introduced, my dad made a little less than $6,000 per year gross pay as a Miami Herald reporter.  That transceiver would have cost about a quarter of a year's pay. And $6000/yr gross income was solid middle class. A family of four could live very well on $6K, 50 years ago. What I meant was that a KWM-2 and power supply/speaker cost less than top-of-the-line separates like a 75A-4 and HT-32B. Or compare the price of an S-line and a KWM-2. To get an idea of the influence of the KWM-2, google "LWM-3"...  Fast forward a bit.  When I bought a Ten-Tec Omni VI, the new cost was a small fraction of a year's pay and that rig offered features only dreamed about at the time of the introduction of the Collins rig.  The KWM-2 was smaller and lighter but an HT- 32B and an HQ-170 would have been cheaper by hundreds of dollars. Agreed. But the KWM-2 put the idea of the one-box station out there in a big way. A lot of less-expensive transceivers with minimal controls followed. People saw the success of the KWM-2 and designed less-expensive alternatives based on the idea. Add to this the grounded-grid linear amplifier and things really changed. High power 'phone became not only less expensive but a lot smaller and lighter. Transceivers and matched-pair separates became the new paradigm in HF ham gear; AM wasn't part of that. There are a couple of "duh" factors buried in there for us to mull over. It would have been possible for radio amateurs to have built and used grounded-grid linear amps for use with AM rigs much earlier.  A rig such as the Johnson Ranger would have driven one to a KW AM input with ease. Some hams did that but the big problem was the low efficiency of AM linear without the use of special circuits like the Doherty, which isn't the fastest QSY circuit. With AM linear you only get 30-35% carrier efficiency. Which means 300-350 watts carrier at the old 1 kW legal limit. Plus your final tubes have to be able to dissipate 650-700 watts! The same results could be had from a 450-watt class plate-modulated AM rig - say, a pair of 812As modulated by a pair of 811As. AM also required power supplies that could stand the 100% duty cycle of the mode. The low duty cycle of early unprocessed SSB rigs meant a lot of liberty could be taken in PSU design. The end result was rigs like the NCX-3 and the SB-100, which cost as much as a good receiver but were complete 100-watt SSB stations that you could indeed set up on a card table. When Heath introduced the SB-200 in 1954, it cost $200. Legal limit on CW, 1200 watts PEP on SSB (input). That was a lot cheaper than the equivalent AM, and would fit on the card table. IOW, high power AM cost a lot of dough and a lot of space/weight. The SSB transceiver/GG linear paradigm drastically reduced those requirements. Fun fact: AFAIK only two 1 kW-input-legal-limit plate-modulated AM rigs were ever made for the amateur market: the Collins KW-1 and the Johnson Desk Kilowatt. Total production was very limited - maybe 2000 units combined. I can't begin to recall the number of models of legal-limit GG amplifiers made. EFJ Thunderbolt, SB-220, Heath KL-1... More to come... 73 de Jim, N2EY |
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