3 vintage Mullard El34/6CA7 including a very early and rare Xf1 with a larger brown base and very large singe halo getter. One Mullard is a dual halo getter Xf2, tests NOS. And one is an Xf4, tests a very strong NOS.All have Mullard codes. Xf1: pre-1960 B8B (Blackburn factory, 1958, February). Xf2: B4J4 (Blackburn factory, 1964, 4th week of October), Xf4: B9J3 (Blackburn factory, 1969, 3rd week of October). The big base Xf1 had no lettering (but clear date codes), a large brown base and a very large single halo getter with much of the chrome getting still intact. The dual halo getter Xf2 reads “DYNACO by Mullard, Made in Great Britain” with most of the chrome getting removed and a small mark on one plate. The Xf4 appears new and is branded “GE Electric tube CL34 6CA7, Made in Great Britain” with full shiny chrome getting. Test results. Xf4 8500 gm (very strong NOS). Xf2 7750 gm (strong NOS). XF1 2750 gm (1430 gm is minimum). Testing is done on a Weston 981 type 3 for gas, leaks, shorts and transconductance. NOS EL34/6CA7 tubes measure 6500 and above on my tester. I have established this range by testing a number of NOS Mullard and current production EL34/6CA7 tubes. The REJECT reading on my tester is 1430 gm and below. $350 for all 3 tubes. Price includes US PayPal fees and USPS Priority shipping within the continental US. Questions are welcome.
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