From what I'd previously understood, RCA abruptly swtiched completely over to solid-state after the 1974 model year. I've seen a 1975 RCA product guide, and I don't think it listed any tube/tube-hybrid stuff at all. ...but here's a KCS-189 (a cute li'l 9-inch B&W portable) that I just found that plainly identifies itself as a 1975 model. Could it have been some sort of short-lived "holdover" just to get rid of leftover parts inventory? I don't think I've ever seen another 1975-marked RCA TV that wasn't solid-state.

BTW, the '74 RCA product reference describes the KCS-189 as a "hybrid" chassis, but that really seems like stretching things a bit. It looks like there's only *one* transistor on the chassis-- it's used as the 2nd video IF amp. On the tuner, the VHF mixer/oscillator and the UHF osciallator are transistors, but the RF amp is still a tube. Everything else is tube-based (aside from the usual handful of semiconductor diodes, of course).

RCA was pretty much solid state from 1970 on. One freak chassis they built was the CTC-39 introduced in 1974 while the XL-100 was going full blast. The 39 was all tubes except for the HV rectifiier. I have discussed this before with many in the know and all believe this was getting rid of old inventory. There must have been some inventory! You just don't tool up to only build a few sets! It wasn't a bad chassis either.

I had a '74 15" RCA B&W that was all tube. Woodgrain plastic cabinet sitting on a chrome and woodgrain roll about cart.

I would assume that this set, like most bw portables of the 70s, was made in Taiwan? It wouldn't surprise me if the factories over there kept cranking out tube stuff even later for sale elsewhere. This example has got to be the very end of the line for RCA, though. 74/75 was the turning point for just about everyone. RCA did have lots of tube/hybrid stuff on the market in the early seventies. Those low-focus voltage color portables must have been very good sellers, for one.

Which is better, tube-chassis or solid-state? What are the pros and cons in each?

I thought the CTC-39 was a 69/70 or so set? I had one and it had a tube HV rectifier and regulator, but a solid state IF. I think it was a 39, or am I thinking of the 38? It had the old RCA logo.

Which is better, tube-chassis or solid-state? What are the pros and cons in each?

Both have their followers. Tube receivers, properly designed ones, that is, have equivalent performance to their SS counterparts - when comparing similarly-equipped chassis. Where SS receivers take the lead, IMHO, is in technical advances not present during the heyday of tubes, such as comb filters. Maybe Pete could come up with a tube-type comb filter for the CT-100!

Tube receivers suffer from cumulative heat damage, especially those with 1950's peanut-brittle PCBA's, and can have all the faults possible in one tube times a dozen on up, per the tube count. Tubes can age rapidly if worked too hard. SS units also suffer from heat, but to a lesser degree, and have more current-surge issues that arise when the design-inherent large capacitors age poorly. BAM! SNAP! POW!

One issue unknown when SS units became popular is longevity of the devices, both physically and commercially. When the jungle IC in a TV becomes unobtanium, is that ever so frustrating! It's been 20-plus years since I saw a color portable returned unrepairable due to no replacement flyback being available. If no original is to be had, you face a different story since the once-crowded flyback-replacement field has become a ghost story, and modern economics dictates NOT supporting older products all too soon after production ends! Germanium-era units are the worst, since silicon vendors ran away years ago from most OEM replacements.

But there is nothing, I mean nothing like the magical aroma wafting up from inside the cabinet of an old tube monster, like my first - a '52 Sylvania 21-incher! Stick your nose in and enjoy! :thmbsp:

As much as I like restoring and using old tube sets, I have yet to see a tube set that could compete with a decent solid state set for picture quality. Even early solid state sets generally look a lot better that their tube peers. That's not to say that tube sets can't have an excellent picture. You just have to learn to look past some of their flaws (flaws such as poor DC restoration, worse power supply regulation, and worse stability.

The main problem is that tube circuit designs tend to be a little less complex than they really should be because it's so expensive to add a few extra tubes to every circuit (more tubes means more space, heat, and power). Transistors and ICs are much smaller, and use less power so that the cost-performance compromise shifts a little more toward the performance side.

I have no doubt that a tube professional monitor with no design short cuts would work as well as a solid state set, but the cost and complexity wouldn't work for a regular TV.

RCA was pretty much solid state from 1970 on. One freak chassis they built was the CTC-39 introduced in 1974 while the XL-100 was going full blast. The 39 was all tubes except for the HV rectifiier. ... It wasn't a bad chassis either.

My grandmother had a CTC39. It replaced a B&W console she had before that. She got it around 1974, and it was having problems around 1984 or so. I think she put a lot of hours on it, what with soap operas and of course evening prime time. We inherited it about then. One issue was that it could get UHF but not VHF. Probably a bad local oscillator in the VHF tuner, but my brother tossed it. :thumbsdn:

The CTC-39 was produced until 1974...am not sure of the first year of production but probably around 1970. The only difference between the CTC-39 and the CTC-38 was that the 39 had the Accu-tint (A/T) circuit and may have had additional failsafe protection on the HV regulator. Both the 38 and 39 used tube type HV rectifiers and regulators and had solid state IF stages.
The CTC-39's came in a variety of cabinet styles, some very similar to the CTC-38's and some with the more modern 25V" picture tubes.

All of the 39's (to my knowledge) used the modern block letter RCA logo. The earlier 38's used the old RCA Victor logo and cabinet style of the CTC-31, while the later 38's used the RCA block letter logo and more modern cabinet styling with the pull out control panel.

I would assume that this set, like most bw portables of the 70s, was made in Taiwan? It wouldn't surprise me if the factories over there kept cranking out tube stuff even later for sale elsewhere. This example has got to be the very end of the line for RCA, though. 74/75 was the turning point for just about everyone. RCA did have lots of tube/hybrid stuff on the market in the early seventies. Those low-focus voltage color portables must have been very good sellers, for one.

Yep, it's made in Taiwan. I think some of RCA's tube-type B&W portables were still made in the USA even in the 70's though.

You're right that RCA still had a lot of tube/hybrid stuff in the early 70's; even the 1974 RCA Product Technical Manual still shows a whopping *ten* different tube and tube-hybrid B&W chassis in production for the '74 model year (compared with only four solid-state B&W chassis), and *six* different hybrid color chassis (compared with four solid-state color chassis). I suspect a lot of those "continuing" tube chassis in '74 were pretty much intended as use-up-the-remaining-parts-inventory sets though, especially since there seems to be a lot of "overlap" in some of those B&W models offered.