This new old stock, new in box RCA 807 / FU7 output tube was tested with adapters on our Maxi-Matcher 2 for shorts, gas and transconductance with 400 volts on the plates and a bias of -48 volts. There were no shorts or gas.
Plate current draw was 36 milliamps while transconductance measured 2300 micromhos. (New 5933s typically test from the mid-teens to mid-30s with transconductance from 2200 micromhos).
I am playing it now in my Musical Paradise 301 MK 3 (with an adapter, not included) with Pink Floyd's "Obscured By Clouds" and it sounds terrific. It is dead quiet when the preamp is muted and has excellent frequency response, sound-staging, and dynamics.
WE HAVE TENS OF THOUSANDS OF VACUUM TUBES IN STOCK. IF IT'S NOT LISTED, WE MAY HAVE IT. PLEASE ALSO SEE OUT ETSY SISTER SITE "LOWTECHTWOO" AND/OR CALL OR TEXT US AT 202-372-6931 IF YOU DO NOT SEE WHAT YOU NEED OR HAVE ANY QUESTIONS.
WE HAVE UPDATED OUR TERMS AND CONDITIONS. PLEASE PERUSE THE FOLLOWING:
1. MOST OF THE TUBES WE SELL ARE OVER 70 YEARS OLD. WE CANNOT GUARANTEE FOR FAILURES AFTER POWER UP AS THERE IS NO WAY TO DETERMINE HOW TUBES WILL INTERACT WITH YOUR ELECTRONICS OR IF THEY WERE MISTREATED IN TRANSIT; NOR IS THERE A WAY TO DETERMINE WHETHER THEY MAY HAVE FATAL FLAWS! WE CAN ONLY TEST FOR THE PARAMETERS MENTIONED IN THE LISTING. WE CANNOT TEST FOR CATASTROPHIC FAILURE. IF A TUBE FAILS AFTER YOU GET IT, IT IS YOUR TUBE THAT HAS FAILED. THERE IS A .1 % CHANCE THIS MIGHT HAPPEN. BE WARNED. NO REFUNDS IN SUCH CASES.
2. IN NEARLY 9000 SALES, WE HAVE HAD A DOZEN OR SO LESS-THAN-FOUR-STAR REVIEWS OR HAVE LOST A CUSTOMER BECAUSE WE REFUSED TO EITHER ISSUE A REFUND FOR A TUBE THAT WENT BAD AFTER IT HAD BEEN USED OR A BUYER DID NOT LOOK AT THE PICTURES AND/OR READ A DESCRIPTION THOROUGHLY.
3. TUBES ARE GUARANTEED GOOD ON SHIPMENT. IF YOU FEAR DAMAGE OR LOSS OF PARCEL IN TRANSIT, PLEASE INSURE THEM! OUR SHIPPING RESPONSIBILITY ENDS WHEN THE PARCEL IS ACCEPTED AND SCANNED BY THE US POSTAL SERVICE. ETSY IS CLEAR ON THIS.
SOMETIMES THERE ARE INITIAL SCANNING DELAYS. WE HAVE ACCESS TO THE SAME INFORMATION YOU DO AND IT IS YOUR RESPONSIBILITY TO DEAL WITH THE USPS SHOULD THERE BE DELAYS OR LOSS OF A SCANNED PACKAGE. PLEASE BE PATIENT FOR THE FIRST DAY OR TWO IF THE PACKAGE IS STILL MARKED AS "PRE-TRANSIT." WE SHIP THE DAY AFTER THE SALE IF THE SALE WAS AFTER 9:30 AM EASTERN TIME.
4. THIS IS NOT AMAZON. THERE WILL BE NO REPLACEMENTS FOR LOST PACKAGES OR TUBES THAT FAIL. IN PRACTICE THIS MEANS YOU TAKE ON THE RESPONSIBILITY FOR THE LOSS IF THE PACKAGE IS MARKED AS "IN TRANSIT" OR AS "DELIVERED." MAIL GETS MISPLACED, STOLEN AND LOST. SOME COUNTRIES DO NOT HAVE INTERNAL TRACKING. CHINA IS AN EXCELLENT EXAMPLE. IF YOUR COUNTRY IS SIMILAR, IT IS YOUR RESPONSIBILITY TO INTERACT WITH YOUR CUSTOMS AND POSTAL AUTHORITIES TO FIND THE PACKAGE. CUSTOMS DELAYS CAN ADD WEEKS TO DELIVERIES.
5. I BUY TUBES IN BULK. 10-15% OF THEM ARE NOT SUITABLE FOR HIGH END AUDIO APPLICATIONS. THAT LOSS RATE IS REFLECTED IN OUR PRICES. I LISTEN TO THESE TUBES IN TUBE EQUIPMENT. SOMETIMES TUBES THAT TEST WELL HAVE PROBLEMS AND SOUND AWFUL. THAT IS ALL I CAN DO. IF THERE WERE A TEST FOR FUTURE FAILURE, I WOULD USE IT. THERE ISN'T. THERE IS RISK IN LIFE. THESE PRODUCTS ARE NO LONGER MADE. THERE ARE NO MANUFACTURERS TO TAKE PRODUCT BACK BECAUSE OF DESIGN FAILURES OR QUALITY-CONTROL ISSUES. THE PRODUCT DEVELOPMENT AND IMPROVEMENT CYCLE IS OVER.