Quote:
Originally Posted by John KC0G
It is very good to see the Marconi information online. Receivers are listed at:
[url]http://marconiincommunications.pbworks.com/w/page/69290381/Receivers%20-%20Products[/url
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Certainly there were quite a few Marconi HF receivers back in the valve era, ranging from quite elaborate to relatively simple. Given that Marconi was essentially supplying to the commercial and industrial market, I imagine that many of the more specialized receivers were aimed a specific set of tasks for point-to-point (PTP) receiving stations.
The same Marconi staffer, namely F.W.J. Sainsbury (FWJS), who wrote the article on HF receivers in Electronic Engineering (EE), 1954 June, also wrote section 16 of the Radio and Television Engineer’s Reference Book (R&TVERB), “Commercial High Frequency Radio Links”. Essentially the same article appeared in the 1st (1954), 3rd (1960) and 4th (1963) editions. (Probably it was also in the 2nd edition (1956), but I do not have that.) Therein FWJS described, without naming them, what were clearly the HR91 telegraph and HR93 ISB/SSB receivers, although circuit schematics were not provided. Accordingly I have extracted (from the 3rd edition) the part of section 16 that deals with those receivers, attached.
R&TVERB III p.16-13 to 26.pdf
FWJS also contributed section 22 of R&TVERB, “Communications Receivers”, this also being essentially the same across the 1st, 3rd and 4th editions. In that case, for the “worked example”, in this case with a circuit schematic, he used what looks very like a CR150 variant, although which one I have not figured out. Again I have extracted the part (from the 3rd edition) that deals with this receiver.
R&TVERB III p.22-16 to 22.pdf
The original CR150 covered 2.0 to 60 MHz in 5 bands, and was double conversion with IFs of 1.6 MHz and 465 kHz. The CRD150 was the triple diversity version of this receiver. The CRD150/20 appears to have been a derivative, used in the CRD150/20B + SSR2 diversity SSB receiver – which makes it very relevant here - and the CRD150/20B + HSR1 diversity telegraph receiver. These two appear to have been Marconi’s top point-to-point offerings before the advent of the HR91 and HR92/93 in 1952. As best I can determine, the individual receivers in the CRD150/20B assembly were of the CR150/4 type. This covered 1.5 to 30 MHz in five bands, with IFs of 1.2 MHz and 465 kHz.
The CR150/3 was said to be a redesigned CR150, with the same coverage and same IFs, and with the provision for crystal control of the first oscillator. Possibly the CR150/4 incorporated the same changes but had different frequency coverage to suit the point-to-point requirements.
Later came the CR150/6, which used miniature valves and covered 2.0 to 32 MHz in four bands with IFs of 1.6 MHz and 465 kHz. It was in place by 1958, but how much earlier than that I don’t know.
The “unknown” CR150-series receiver described in R&TVERB used miniature valves, tuned 1.5 to 30 MHz in five bands, like the CR150/4, and had IFs of 1.2 MHz and 100 kHz. Possibly the choice of the 100 kHz second IF was to facilitate coupling to outboard processors that expected to see a 100 kHz input, probably the modal final IF in much such point-to-point station equipment of the period. But then one could wonder why the – presumably later – CR150/6 went back to 465 kHz.
The unknown receiver would likely have been in place ahead of the 1954 publication date of R&TVERB 1st, perhaps even in 1953. The HR22 Group 3 SSB receiver was in some ways a derivative of the CR150 series. It used miniature valves, covered 2.0 to 32 MHz in four bands and had IFs of 1.6 MHz and 100 kHz. It was in place by mid-1954, when the EE article was published, but probably not much before. Whereas the unknown receiver used many Osram “77-series” valves, as might be expected, the HR22 appears to have been based to some extent of the lesser-known Osram “727” series which had been announced around 1953-54, although they were simply renamed American standard valves.
Given that the CR150 series was a general-purpose receiver, with some sold on the surplus market, and not just a point-to-point specialty item, I imagine that someone, somewhere has amassed chapter, verse and minutiae on its chronology and variants, and the information is on the web somewhere – I just have not yet found it.
Quote:
Originally Posted by John KC0G
Re. post #65, I am 430 miles north of Kansas City, MO. Dallas, TX is about 500 miles south. The Linda Hall library is too far away just to drop into.
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Yes, hardly “drop-in” distance from Dallas. Had I known about it, it was the kind of trip I might have done towards the year-end to use up a couple or three vacation days that otherwise would be lost. The strange thing is, my neighbours and friends in Dallas still had a farmhouse in western Iowa – between the river and the Loess Hills – that they used as a vacation destination, and I visited there a few times, driving through KC, so Linda Hall would have been an easy stop-off.
Cheers,