View Single Post
Old 10-09-2016, 11:36 AM
plurn plurn is offline
Join Date: Jun 2014
Posts: 36

Originally Posted by microstrip View Post
I also bought a large stock of the same type PCC88 Philips with codes DJER 4F and 4G. I have measured about 10 and they are in general low noise and both triodes are matched in gain and DC - an important parameter as the sections work in parallel in my LP275s. From these 10 only one had one noisy triode in the low frequencies - it is now burning-in for a few days, as I have found that some tubes that are initially noisy become silent after 50-100 hours burn-in.

Measuring a few used noisy ECC88/6922 I have found that their triodes were significantly unbalanced. Probably tubes in these conditions will ear out much faster as the tube current does not split equally between the triodes.
That is good that they have acceptable measurements and that a good proportion of them are usable. Thanks for reporting the codes. I would think 4F = 1964 June, and 4G = 1964 July.

You have inspired me to check the codes on my tubes more closely. I have found that on some of them, the second row of codes is just barely visible and almost readable with a magnifying glass and a flashlight.

Under the DJER row, mine seem to have a row with three characters starting with a partial circle character, followed by 4H. I think the partial circle character must be this one for "Elektronski Industija, Nis, Yugoslavia":

I would think the 4H would be 1964 August.


Last edited by plurn; 06-08-2018 at 04:25 PM. Reason: updated image url
Reply With Quote