I finally got around to digging out another blocking cap, unfortunately, same results. It draws more current with more drive, but plate and load controls have no effect on plate current, grid curren
For minimum airflow resistance for a forced air cooled amplifier it would seem the blower needs to discharge in a straight line directly into the underside of the valve socket. This leads to a fairl
Greetings Ian Besides the lower back pressure advantage of blowing into the anode compartment, this method also cools the tank components. This helps reduce thermal tuning drift in very hi-Q tanks.
I am still refurbishing my SB-230 and I have noticed the grid ring on the tube looks badly tarnished. I have checked it with an ohm meter and I see a low resistant connection but that tells me nothi
I am looking for a good source of 572B tubes. I have been buying them off eBay and these are Chinese tube. They haven't last more than a year. Any have any ideas, I would appreciate it. Please send
I have been fighting with my SB-230. Initially I was getting 500 watts CW key down with about 85 watts drive and over 600 on my peak reading meter on SSB. I slowly lost gain and finally I was only a
Hi Paul Kelley, N1BUG: << I'm trying to understand a problem with one of my amps. It is homebrew, 160-10 meters, using a 4CX1500B with screen grounded, grid RF grounded, cathode drive. It uses a conv
So then what is the Radio Handbook talking about where it uses a 10ohm/20w one between the plate choke and the +HV? That's going to be quite a resistor, inasmuch as 4KV across a 30 ohm resistor amou
Way back in my foggy memory somewhere, I remember using and amplifier made by B & W. I think it was a "Model 1500", but I'm not sure. It used a pair of 813's. What I remember as unique about this am
What I miss, in terms of availability, are capacitors suitable for building good, safe, legal limit low pass filters, that don't blow up even at somewhat elevated SWR. What we need for that are capa
I am looking for a matched pair of MRF-422. Does anyone have a set they are willing part with. Please send response to dansawyer at earthlink dot net http://www.mouser.com/ProductDetail/M-A-COM-Tech
I discovered some new (to me) information on maximizing the life of amplifier tubes with thoriated-tungsten filaments. I just uploaded it to: http://www.w0btu.com/miller-larson_effect.html Basically
I built a dummy load consisting of 4 x 200 ohm globars in parallel. Each resistor is 12 inches long x 1 inch OD. Each resistor resides in its own 3 inch OD x 12 inch long AL pipe. All 4 x AL pipes a
Id check the SSB/CW switch carefully for arcing to a metal part. Common problem with an underrated switch. One day when I switched from CW to SSB mode on my Clipperton-L it blew the fuse with a good
I have a 4CX5000A Dud that I am incorporating into a tube display in the shack. What would be the best stuff to remove the tarnish on the Plate section ? Tarn-X is available in some drugstores, hard
I was simulating (with LTspice) a three phase power supply where the secondary is in star configuration with full wave rectification. You can get also a second voltage from this by connecting to the
/*snip*/ I insulted it off the concrete floor with 1 foot wide rubber mats. It neasured 30 ohms to AC power common. be conductive. /*snip*/ A friend asked me to test the vinyl jacket on common RG-8/U
Sorry to belabor this some, but if we read Mr. Parascondola's first message about the presence of voltage inside some Ameritron amplifiers, he seemed to say that it did matter which side of the hot
A very astute observation Peter. I don't know the current requirements for various levels of licenses in the UK but over here even a certified retard can pass an Extra as no CW is required and anyon
Has anyone had experience using microwave oven door glass as a shielded viewport for an HF amp? Any ideas about attenuation at HF frequencies? I'm considering a three-tube 3500ZG amp as one of my wi