Conference cvg::hamradio_iii

    Some random notes on this:
    
    The 35 and 51 (551) seem to be generally interchangeable, though it
    seems that one is a tetrode and one is a pentode.. shortly after they
    were introduced, most manufacturers shipped only a single version
    marked 35/51. 
    
    The 1619 is in no way related to the 27; a 1619 is a 2.5V *filament*
    version of the 6L6, and it is on an octal base. Given the other tubes in
    that radio, it was built far before octal tubes were introduced - so
    this sounds like a rewire.. probably in the late 40's when 1619's were
    dirt cheap in the surplus market. (the 1619 is listed in the '63 Radio
    Amateur's Handbook, and probably earlier editions as well.. it is not a
    standard EIA base diagram) .. I can't see why anybody would put these
    in anything other than a power-output stage, though..
    
    The 27 is a heater-cathode triode, if my memory isn't failing..
    
    ...tom

    More on the 551/35:
    
    The 551 (51) was the first remote-cutoff tetrode, and it was released
    (1931) by a group of three manufacturers (I forget which, Arcturus was
    probably one); RCA came out with the 235 (35) very shortly thereafter -
    also a remote-cutoff tetrode. These were almost identical, so soon
    everybody (except RCA, of course) was labeling a single design as
    35/51. By the end of 1935, the 551 (51) had been discontinued and only
    35's were available.
    
    (this gives you a clue as to when your radio was made; if it specifies
    a "551", it must have been early thirties)
    
    
          G2
           o
             x G1(cap)
      P o     o K
    
         O   O
         F   F
    
    
    ...tom
    

Thanks again Tom --

looks like all the tubes are 2.5 filament types and I 
do not have to worry about the 35/51 mix.

the 1619's are still a mystery to me -
it looks like they are mounted on a socket converter, 
which off the top of my head, has sticky on it 
"1619 to 47" which would make sense with your story
about it being a LF power amp...

may be somebody played around with the tubes in these
chassis before I got my hands on it...

the 2 - 47's in the LF pushpull are missing...
and the 1619's are in the upper chassis 
behind the IF stages in what I suspect are
detector and LF pre-amp slots....
( did not follow the wiring inside yet...)

btw. I found I pretty helpful site on the web for Antique
radio fans check it out..

http://rlan.net/NostalgiaAir/index.htm

has tubes and substitutes and quite a collection of scanned in
schematics..

/c 

    the 1619 on the converter must have just been stuck in the 27 sockets
    "because they fit".. looking at the base diagrams, a 47 and a 27 are
    nowhere near compatible.. so my guess is that the 1619+converters sould
    go in the 47 sockets, and you'll need to find some 27s for the 27
    sockets..
    
    There is a schematic of the silver-marshall "model Q" at Nostalgia Air;
    it might at least give you some clues as to how they were thinking
    when they designed whatever it is that you have..
    
    ...tom

Part of the puzzle -- I think you're right

the 1619s were replacements used with a socket converter
for the 47 tubes.. plugged into the wrong tube slots..

I'll wait and see if I can dig up some pinout for
the 1619s - the 47 tubes are pretty pricey..
although I'm chasing somebody who has( had) some
second hand willing to sell for $2.50 / piece

most tube dealers want anywhere from $15-25 for tested ones..

the model Q schematic did not help out ( I pulled last week)
Looks like this one I have is a lot older than the Q.

I do not think not having schematic is a problem as soon as
I get hold of some 1619 tube data !

I traced the Power/LF section and drew the CC myself and
the top chassis of this beast is large, and the very spacey
layout makes it relatively easy to see how stuff is hooked up.

almost done with stripping the wooden console - 
the 6 nice legs giving me a headache - 
very detailed and a pain to get the varnish off -- 

good thing is : 
at least it keeps me out of trouble --
must be getting old -- 
(stripping 3 pairs of nice legs...
 and figuring to stay out of trouble..)
;^)

/c

    1619: 
    
    Pinout:
    
    according to the '47 _handbook_ it's RMA 7AC, but 7AC is a
    heater-cathode type.. the '63 _handbook_ shows it as Fig 74:
    1: Shell
    2: F
    3: P
    4: G2
    5: G1
    6: missing
    7: F
    8: beam-forming plates
    
    Characteristics:
    
    Fil: 2.5V 2A
    Plate: 400Vmax, 15Wmax
    Screen: 300Vmax 4Wmax
    full ratings to 45MHz.
    
    ...tom