I do not know the specifics of these tubes other than what I have given above, since I have not consulted my tube manual, even though it is in the other room. Most likely maximum voltage ratings will be similar for the two tubes, but you should consult your manual to be sure, and to be sure that you won't exceed the rated maximum if that is possible. Also, most likely both tubes contain a 6.3 volt filament. However, if they are going to be used in a series string arrangement, it should be known whether or not they both consume the same amount of current. More current will cause the tube to fail to light, and less current will cause the tube to glow too brightly, and possibly burn out. For parallel operation, small differences in current draw are of no concern, and should only be of concern when the difference is great and there is a chance of excessive current draw from the power transformer. Since either both of these tubes draws .3 amperes, or one draws .150 and one .3, there is almost no concern for excessive current draw.
T.
Sharp cut-off designed tubes have uniformly spaced control grid windings. As negative bias is increased, the entire grid runs into the cut-off region. This may introduce distortion in some circuits, and cause early detection of radio signals.
The mixing of these two kinds of tubes is most critical in grid leak and square plate detector circuits, and is less of a concern for pure RF amplification circuits, though trouble can be caused here, too, by the insertion of the wrong kind of tube. Usually no physical harm is done, but performance may suffer.
....Try the swap and see if you like it.
T.
T.
But in an AA6 you may see the 1st and 3rd tubes are 6SS7
Like the Farnsworth model ET066:
it uses:
6SS7 12SA7 6SS7 12SQ7 50L6 35Z5
:::Hello all. Can a 6SS7 be used as a substitute for a 6SJ7 or could this be hazardous??Thanks for info
:::Thankyou gentlemen for this information
::The 6SJ7 just arrived in the mail, so I put it in place of the 6SS7 and BOOM the volume jumped to life ,so must be the double current draw of the filament!
:
Filament current affects tube gain little in most cases, so long as the voltage across the filament is correct.
T.
An example of how filament current has little to do with gain is the comparison of the 6J7 and the 6W7 type tubes. The former has .3 ampere filament and the latter has a .15 ampere filament. Both have similar gain, and it will most likely be noted that both amplify equally (as I have noted, since I own both types of tubes). Only in cases of high power would the cathode size (and, indirectly, filament current draw) be of concern. Both tubes will, of course, function similarly in a parallel filament configuration. On the other hand, trouble will arise if a series filament string is employed, and one tube is substituted for a circuit designed for the other. The details of what will happen here can be found in the information I originally wrote further up this thread.
T.
The 6SS7 is a remote cutoff tube with 150 ma filament. 6SJ7 is sharp cutoff with 300 ma filament.
In a power transformer operated radio filament current makes little difference as long as it doesn't overheat.
A 6SJ7 may distort on strong stations if used in an IF stage. 6SK7 (remote cutoff) is a better sub for 6SS7 in a power transformer operted radio.
In an AC/DC radio 12SK7 will replace 6SS7. Even though voltage is different current is more important here.
Norm
:Hello all. Can a 6SS7 be used as a substitute for a 6SJ7 or could this be hazardous??Thanks for info
: