Print

[K6EE]

Hi,

I recently found a nice Barker & Williamson L1000 with 2 grounded grid 813, I am slowly preparing to restore. Any advice welcome, if you are running an L1000 or homebrew 2 x 813 amplifier...

Thanks, Fritz

[W9WQA]

i have a home brew 2x 813 amp.  built over years kind of on the fly.  from misc schematics !! dont have a complete final print but it runs 3200+ v and loads up to 1 amp !!,dummy load.

mine is not too good at 20 and up, needs more tweaking but will out 800 below.  big noise on 40 !!
i missed a b/w tuning section yrs ago,  wanted one.

u r lucky !!
see my pix...
let us know about it...

[W9WQA]

sorry cant do pix???

see me on qrz !!

[K6EE]

Hi W9WQA,

Thanks for your reply! My model is a B&W L-1000A around 1956 (made in Upper Darby) - unfortunately pictures seem indeed not to work here.

It came also with the transmitter 5100B+51SB-B adapter which I already have up and running.

In the L-1000A the power supply the rectifier tubes have been replaced by solid state, otherwise everything seems original. Mine has also the unit with the input bandpasses for the classical bands installed, which seems semi-rare. I was mainly gearing up parts so far. I got 12V coax relays (that I intent to power by rectifying the 12V filament voltage). I also got more than enough (6) 813 replacement tubes, a lucky coincidence. Testing the tubes will be a chicken-egg problem with getting the PA going - as the tube tester cannot do it.

As I will start looking it through and making first tests, I definitely will have concrete questions for you. 

tnx es vy 73, Fritz

[W9WQA]

yeah,   good to have spares, i have 6 or 8...
filament is 10 v at 5 amps each. i have sockets also and big mica caps if you add anything.
also big 4 pole relays. i use one for changeover.
i like 813's, thinking of doing a strip of 6 sockets to keep em warm and light the room...!
good luck, and one hand in your pocket!!

[W1QJ]

I had one of these years ago.  Mine had a homebrew power supply.  The tank circuit was an 850a as I recall.  It worked. About 600 watts output.

[W9WQA]

my ps is surplus from heath sb 1000, 3200-3500v

[K6EE]

>>One hand in your pocket!!
Absolutely.

About the original B&W PS, the manual says 3KV - and I suppose about 1A.

[VE7RF]

I bought a HB 2 x 813 RF deck... and built my own B+ supply.  Managed 1100 watts pep out. That was 1974. I had a dozen new, spare tubes for that amp, and never had to use any of em.   Later sold the RF deck, with the original pair of tubes.... plus the dozen spares.

Buddy across town asked me to test his hb 2 x 813 amp a few yrs back.   I used the B+ from one of my L4B power supply's.
Managed 1100 watts pep out with that amp too.   I recognized the hb amp right away.  I 1st saw it back in 1971, before I got my ticket.  A friend of my dad's built it in the 60's. My father took me over there one weekend to see his friends station. It still had the same tubes in it, since he had marked them. 

[W3SLK]

My good friend and elmer Eric, WB4VVI(SK), had an amp, (I now own it) where he ran 4KV on the 813's. When I asked him about that he told me that 813's are rated for 2KV in AM service and will see twice that when 100% modulated. He got around the peak issue by running a pair of muffin fans across the tubes. It worked good. But he also told me not to miss tune it or those tubes are toast at 4KV! I think the 813 is most durable tube ever made. Most bang for the buck! However I am biased, (pun intended), since I feel I cornered the market on them!

[W9WQA]

i started with a box of ?10 a friend of my bro got when the old wacb went solid state.

i run no bias.  do you?
if so tell me how.