From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: Digital divide by ten, 1949 style
References: <3D84D4B3.50B511EF@webaccess.net> <3D850A3C.31381AD5@webaccess.net>
Date: Mon, 16 Sep 2002 01:03:21 GMT
NNTP-Posting-Date: Sun, 15 Sep 2002 18:03:21 PDT
Philip Nasadowski wrote:
> In article <3D850A3C.31381AD5@webaccess.net>,
> Chuck Simmons wrote:
> > I did run across an oddity I had forgotten about. There was an AA5
> > variant that used a rectifier with a 117 volt filament. The other tubes
> > had 1 volt filaments. These were rare indeed.
> Some battery portables had this, to allow 'plug in' operation, and
> battery operation
That explains why I remember that one. It was a bit rare.
> > There were a couple of other AA5 variants that existed. Car radios were
> > essentially the AA5 but the tube numbers all began with 6 and then
> > latter 12. The plate supply in car radios was derived from a vibrator
> > and tube rectifier or else a vibrator with synchronous rectifier
> > contacts.
> The 6.3 volt supply almost all transformer type tube equipment in the US
> used was because or early car radios.
> Tubes were first all 2.5 volt (for whatever reason), but then they
> became 5 volt (briefly). When someone thought of the car radio, it was
> natural tto use the then 6 volt car battery to run it, so RCA and all
> developed 6.3 volt tubes. The first number in a US tube type, but not
> CRTs, generally indicates the voltage needed on the filiment. Thus, a
> 6BA6 was 6 volt, a 12BA6 was 12 volt. On a CRT, the first numbers
> indicated the screen size (in inches), and the P* at the end the
> phosphor. P4 is B&W TV, P22 is color.
Power tubes had numbers all over the map. In my very first job, the big
tubes were 4-400As. They ran with the plates just visably glowing which
was normal for that type of tube. Another friend in the radio business
for FM was the 4X500. The 4 meant it was a tetrode. These occasionally
melted the glass and sucked. I cured that by changing to 4CX500s and
enlarging the neutralization tabs slightly. My all time favorite was the
3CX2500A3. For more than two years I cared for about 65 transmitters in
one building about 35 or so of which transmitters had 6 3CX2500A3s in
push pull parallel for 30KW output from a grounded grid class B
independent sideband linear amplifier in the HF range. Really sweet. I
only once got called out to work on one of those monsters on my days
off. I had 10 or so single output tube 40KW linears that were a horror
story, however. When the suckers caught fire it took a couple of days to
get them back on line. They seemed to catch on fire a lot.
> Rectifier tubes were 5 volts for years, thus transformers had a 6.3 V
> winding (or a tapped 12V), a 5V winging, and whatever high voltage and
> others were needed. 6 volt rectifiers appeared later on, though the 5Y3
> and 5U4 held on.
5 volts hung on until the end in rectifiers. Correct me if I suffer from
poor memory but didn't all of the 866, 872 and 575 tubes have 5 volt
filaments? These, of course were in power applications.
> > True but the comment was more about the superheterodyne than the 6BE6.
> Oh, the 6BE6 sure can go high, RCA said it was suitable for FM broadcast
> radio use too.
> > TVs used germanium diode mixers fairly early on. I forget the earliest
> > tuner I saw that in but it had to be circa 1950 when TV came to the city
> > in which I lived.
> No, they used diode mixers for UHF. UHF has always been diode mixers,
> from day one. VHF tunners were pentode mixers even into the 60's. The
> UHF tunners had a 1N81 or something like that as the diode mixer (I
> never understood how that worked), and later had 1 or 2 varactor diodes
> for AFC. Most TVs used semiconductor diode detectors, as early as '52
> or '53. I have a Bendix where the video was dead. It was the
> *semiconductor* diode detector that was dead. None of the tubes were!
> VHF was pentode (or triode in some early sets), UHF was diode.
OK. I didn't dig into many tuners. It seems to me the common turret
tuner had two tubes. I never looked at the earlier continuous tuning
tuners that didn't last long. I would bet some money that turret tuners
hit the market by 1950. I first saw a TV set in 1949. There were no TV
shows. We watched the test pattern the brand new station was sending
> > The foreign tubes tubes were challenging to get in the US in the 1950s.
> Most were, but stuff like the ECC83 were easy, if you knew what their US
> cross numbers were.
> What I never got was, even today, the high power sweep tubes used in
> color TVs are $$$, even though there's no demand for them, except for
> the %&%^&%^$& hams and audiophools, how think any tube that can handle
> power MUST be placed into some stupid use it wasn't designed for.
> Though my favorite was still the audiophool amp that used like 50 12AX7s
> in a push pull and (very) parrallel output stage...
> To email me, change 'usermale' to 'usermail'
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons firstname.lastname@example.org