+++ B & K 707 TUBE TESTER Mutual Conductance ++ 12AX7 Mod Plus ++ REDUCED $ +++, US $399.00 – Picture 0

+++ B & K 707 TUBE TESTER Mutual Conductance ++ 12AX7 Mod Plus ++ REDUCED $ +++, US $399.00 – Picture 1

+++ B & K 707 TUBE TESTER Mutual Conductance ++ 12AX7 Mod Plus ++ REDUCED $ +++, US $399.00 – Picture 2

+++ B & K 707 TUBE TESTER Mutual Conductance ++ 12AX7 Mod Plus ++ REDUCED $ +++, US $399.00 – Picture 3

+++ B & K 707 TUBE TESTER Mutual Conductance ++ 12AX7 Mod Plus ++ REDUCED $ +++, US $399.00 – Picture 4

+++ B & K 707 TUBE TESTER Mutual Conductance ++ 12AX7 Mod Plus ++ REDUCED $ +++, US $399.00 – Picture 5

+++ B & K 707 TUBE TESTER Mutual Conductance ++ 12AX7 Mod Plus ++ REDUCED $ +++, US $399.00 – Picture 6

+++ B & K 707 TUBE TESTER Mutual Conductance ++ 12AX7 Mod Plus ++ REDUCED $ +++, US $399.00 – Picture 7

+++ B & K 707 TUBE TESTER Mutual Conductance ++ 12AX7 Mod Plus ++ REDUCED $ +++, US $399.00 – Picture 8

+++ B & K 707 TUBE TESTER Mutual Conductance ++ 12AX7 Mod Plus ++ REDUCED $ +++, US $399.00 – Picture 9

+++ B & K 707 TUBE TESTER Mutual Conductance ++ 12AX7 Mod Plus ++ REDUCED $ +++, US $399.00 – Picture 10

+++ B & K 707 TUBE TESTER Mutual Conductance ++ 12AX7 Mod Plus ++ REDUCED $ +++, US $399.00 – Picture 11

+++ B & K 707 Tube Tester Mutual Conductance ++ 12ax7 Mod Plus ++ Reduced $ +++

US $399.00

Bradenton, Florida, United States
Mar 26th

Open on mobile:
QR code

Here is a quality well cared for mutual conductance tester I refurbished that is now ready for full service. I built the regulated solid state rectifier replacement according to a schematic that simulates the voltage drop of the original 83 tube and uses 3W 10 ohm resistors that simulate the tubes filaments. Tested that device on my Hickok 752a as a high test 83 tube, then installed it in the 707. New electrolytic caps were installed, the big ones are Sprague Atom - some of the very best available. Then I replaced the two #55 lamps inside with matched NOS lamps from the same NOS package. Checked all critical resistors for correct resistance. Proceeded to calibrate the tester according to B&K procedures adjusting shorts and grid emmision sensitivity, adjusting signal voltage and DC bias voltage, meter bridge balance, and confiming correct DC plate and screen voltages. Next I rewired socket 24 for dedicated 12AX7 use only and to give full meter swing with test 1 and 2 buttons pushed (as compared to the stock 22 good on the meter.) You may still use socket 8 the old way if desired, it was untouched. Top quality Belden solid core wire was used in this re-wiring, the same gauge and style used at the B&K factory when this 707 was made. Then I checked all heavily used sockets for tightness and adjusted a few sockets for snug like new tube fit. I cleaned the case and the face, not much was neccessary, (looks like I may have forgotten the left inside edge though.) Both extra nice with the fewest of blems (NO social security or other numbers etched into the face as is commonly seen) just a few tiny dings on the cover, very clean indeed. (There were 2 spots on the lens creating two shadow like spots in all the pics, most obvious in the first pic at the middle of the right edge of the blue case, it's not really there. You may notice these "spots" in 3 or more other pics in the same position, upper right. None of these spots are really there on the tester. And a fly it seems landed along the right front edge in that top picture, it's not really there either any more.) Very few marks. Case is in excellent shape and will support the lid hanging over it's edge without any warping or sign of stress. Hinges are shiney. Four factory feet on bottom are like mint. No hidden tears, all nicks are shown. Finally, the 6 main knobs were cleaned and lightly polished. Will test 6LQ6 6JE6C 6LB6 and other novar nine pin ham and cb radio amp types ... as well as all your octals, and 7 & 9 pin preamp "miniature" tubes and compactrons. The B&K 700 series testers have mutual conductance circuitry taken from the pricier Hickoks. The B&Ks relative 0 - 120 scale test results are as accurate as the Hickok service testers. If you need lab quality testing, look for a 539C or similar multi-transformered unit. Just be ready to pay $1200, $1500 or more for one that has been refurbished. From the date on the back of the meter, this 707 must be a 1970 model. And from the lack of cover and face wear (especially the area around test button 1) must have been for personal, not repair shop use. This sale includes the original dual ended grid cap test lead that you don't often see, and a thorough remastered thick manual with instructions, parts list, calibration instructions, the most recent 1978 tube set-up charts and the 81 suppliment, and the fold-out schematic - a beautiful bound manual that opens to any page, easily folds around, and lays nearly flat. Don't let this one slip by. Shipping standard post or priority mail insured and well packed. Check my feedback on the other B&K testers I've refurbished and sold. You too will be happy.

“Regulated SS Rectifier, Re-capped Sprague Atom, 12AX7 MOD, Calibrated. Face and case show very little age.”

Brand	B&K
Country/Region of Manufacture	United States
Model	707