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Questions about RCA 5751tubes

I am needing some help..

I ordered a pair of Sylvania 3 mica Black Plate 5751s for $150
and was sent RCA JRC-5751s instead. Please bear with all my questions.

1. I was told these were better tubes and matched within 2.5%
One tube has a sticker with 1.5/1.5 and the other says 1.6/1.7
Can I tell if these are matched from these values?

2. What do these values mean? Are they an indication of life left
on the tube? If so what values are considered NOS and what
values are considered 50% and 75% life left?

3. Are RCA JRC-5751 Black Plate, 3 mica, (smooth edge top mica)
as good as Sylvania 3 mica Black Plate 5751s?

I was surprised to get a different tube than I ordered but wanted
to ask everyone if this really is a better tube? Anything you can
tell me about this tube would be very appreciated..

More info on these tubes:

The top of the tube (nipple of the tube)is painted half green/half red.
I assume these are military markings..??? What do they mean?

The silk screening is all white but 90% worn off so you can't
read anything but part of the RCA logo, 5751, and JRC

2 black plates

Each tube seems to have 2 paper clip looking supports (one at each
end) to tighten up and better secure all 3 mica disks.

square halos.
tom92602
thorman
1,262 posts
 
You should get what you order no matter what ..No excuses,,,Unless the person selling has a problem and contacts you with an explantion,it ain't the right way to sell......If you order a new Ford and the Salesman drops off a new Chevrolet at your doorstep..You may or may not be too happy.....
mechans
3,048 posts
 
I really cannot speak for the group and cast braod aspertions about the general nature of humility. Tom92602 is clearly not a silly audiophile but a very correct and presumambly serious fellow. He is not a Humble Jackass I aplogize.
I missed one Huge point I really made an idiot of myself.
I thought our OP had asked for RCA and got JRC. I see now he asked for Sylvania and got RCA. this is truly no sarcasm intended at all criminal. That kind of behavior earns dealers a questionable charater tating in this case there is no question he is totally wrong by subbing which ever tube he deems fit too. I mean this perhaps that should be punishable with sanctions and a ban from Agon. Our poster should recieve a pair of excellent triple mica Blackplate 1950 vintage Sylvania 5751s. If he is not allowed to exchange them I will offer a pair of my own to barrow long enough to get an idea of what they are like.
OP please contact me through the AGON mail system.
I am not a dealer but have many tubes and may sell some in the future.
That is the only disclosure of potential conflict of interest I can think of. I do not have Sylvania 3 mica BP 5751s for sale only for him alone to borrow. I have JHs, Gold Brand, (? 3 mica) and Sylvania consumer regular. Many have rubbed or warn print but there is a way to identify them that readily distinguishes them from the JRC RCA which have almost Identical plates and getter rings.
tom92602 OP
65 posts
 
A note to all, I sent the tubes back the very next day
and got my full refund in the mail yesterday. It all
worked out in the end..

Tom
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