This good testing matched pair Sylvania Type 78 tubes with mesh plate, engraved bases and bottom foil D dimple getters was tested in our Jackson 648 and they measured:

Tube One:  76 (Sylvania engraved on base with code J 7 R or B and E 5 R; 78 stenciled on side of glass)
Tube Two:  74 (Sylvania engraved on base with tape from previous owner - will leave for buyer to remove)

Good range is from 70 - 130 on the Jackson.  These test 76% & 74%.  Tube One slightly loose on base (bonding cement debris - will leave for buyer to remove tape/glue on base if needed).

I have several pairs of Type 78s listed so please view those as well.

Tubes ships via United States Postal Service (USPS) Ground Advantage with tracking for domestic sales: Priority Mail is also an option for you.  International sales ship via International Shipping service.


Package weighs ten ounces (10 oz).

Check out other tubes in my store for your equipment needs.

Combined shipping always welcomed.

TUBES ARE GUARANTEED GOOD AND IN WORKING ORDER AT SHIPMENT. TRANSIT VIA POST CAN DAMAGE TUBES.  THIS IS NO FAULT OF OURS BUT THE THIRD 

PARTY ENTITY THAT IS DELIVERING ITEM(S) TO YOU, I.E, USPS, UPS, FEDEX, YOUR NATIONAL CARRIER IF INTERNATIONAL, ETC. PLEASE INSURE THEM! WE 

CANNOT GUARANTEE FAILURES ON YOUR EQUIPMENT AFTER POWER UP AS THERE IS NO WAY TO ASCERTAIN HOW TUBES WILL INTERACT WITH YOUR 

ELECTRONICS; NOR IS THERE A WAY TO DETERMINE WHETHER THEY MAY HAVE FATAL FLAWS IN TUBES THEMSELVES!  THESE ARE USED VACUUM TUBES AND 

TIME MAY HAVE TAKEN A TOLL ON THEM OVER THE MANY YEARS SINCE THEY WERE MANUFACTURED. WE CAN ONLY TEST FOR THE PARAMETERS MENTIONED 

ABOVE IN ONE OR MORE OF THE FOLLOWING EQUIPMENT WE USE FOR MEASURING:  HICKOK 600A, HICKOK 800, MAXI MATCHER & MAXI MATCHER 2.