My chassis is labeled as having 6CB6's (1st and 2nd video IF stages) and that is what are installed, but yesterday I got a copy of the photofact supplemental data sheets for my TV and it has late production changes to the chassis (it's a 1956 Packard Bell 21DK1). In the notes section it says that 6DE6's should be used instead of 6CB6's.

I see that 6DE6's can be substituted for 6CB6's and what I gather from comparing specs is that the 6DE6 is basically a superior version of the 6CB6.

Apparently at some point in the life of this TV (if the supplemental data sheet is to be believed), the original 6DE6's were replaced with 6CB6's because of course the chassis doesn't say that 6DE6's should be used. So the question is, if the 6CB6's seem to be working OK is there any good reason to replace them with 6DE6's? Would it have any impact on the picture at all? Would I just be wasting my time and money if I replaced the tubes now?

Thoughts?

Generally speaking on TV RF/IF tubes if they don't test bad the set works well, and it wasn't some idiots hack substitution for a non/borderline-compatible type leave it how it is. Different tubes can change a TV's alignment, and unless you have the equipment, experience and patience to do a complete TV alignment it is best not to f--- with it.

Many sets went through several production changes in their time on the lines in order to use the cheapest parts, or fix operational issues. Best move is to restore it the way it was, and not try to add production changes it never had.....Unless the change is in a circuit that is working poorly, and all other remedies have been tried.

I had it in my head that the supplemental data applied to my set because when I first glanced at it, I thought it detailed the modifications made for the console version of the TV. So now that you mention it, I realize my set must not have gone through the "late production" changes, which is why the chassis isn't marked with "6DE6" so in retrospect my question was a little silly and therefore I retract it. I'm still very much in a learning phase but loving every minute of it! :)

Thanks for the helpful reply!

You're welcome.
Right now finals have me tired enough that when I first clicked on the link I was half expecting it to be about launching the two tubes at one another to see which one would survive the impact.

You're welcome.
Right now finals have me tired enough that when I first clicked on the link I was half expecting it to be about launching the two tubes at one another to see which one would survive the impact.

You are so right about subs changing the bandpass of the IF amps. I tried 6AK5s to replace 6AG5s in a Dumont dog house. It certainly didn't want to know about that sub!!
BTW, best of luck on the exams! :yes:
Kevin

You are so right about subs changing the bandpass of the IF amps. I tried 6AK5s to replace 6AG5s in a Dumont dog house. It certainly didn't want to know about that sub!!
BTW, best of luck on the exams! :yes:
Kevin

I bought some 6AG5's for my 621TS, that I'm restoring. I also bought some 6BC5's to try, but I'll probably stick with the 6AG5's. The 6BC5 is a later issue 6AG5. It also goes under the 6CE5 type number. :scratch2:

You are so right about subs changing the bandpass of the IF amps. I tried 6AK5s to replace 6AG5s in a Dumont dog house. It certainly didn't want to know about that sub!!
BTW, best of luck on the exams! :yes:
Kevin

Thanks. I think I passed everything by a decent margin (still one course not reporting my grade). With luck when the last of my grades come in tomorrow I'll have confirmation that I'll be receiving a diploma to go in the empty leather binder they gave me during my graduation Saturday....

Unfortunately while cleaning my school laptop prior to turning it in to get the fun programs wiped (so I can keep it for free after graduation) I got enough cleaning fluid in it to prevent it from booting so...... for ~2 weeks (while it is shipped out for repairs) I'll be stuck with using my backup 'media player computer' as my main computer.....Which sucks because I never cofigured it for the web since it was originally only meant to feed tube TVs as it's monitor thru it's s-video jack....I've added a better monitor, but it is still clumsy, and the "wireless" keyboard (which has shorter range than a wired one!) is makin typing hideously clumsy.

I had it in my head that the supplemental data applied to my set because when I first glanced at it, I thought it detailed the modifications made for the console version of the TV. So now that you mention it, I realize my set must not have gone through the "late production" changes, which is why the chassis isn't marked with "6DE6" so in retrospect my question was a little silly and therefore I retract it. I'm still very much in a learning phase but loving every minute of it! :)

Thanks for the helpful reply!
Many times, using a subsitute IF tube can affect the AGC in some circuits.
When I started following this thread, I was thinking about the 6CF6, that was used as the first IF tube in RCA sets. I never thought, there was much difference between the 6CF6 and the 6CB6, used in the second and third stage.