Thanks for the several replies. I see that I left out some important info, as usual. The tube being protected is a TH347, and is expensive, $3500 new, $1400 rebuilt. I have lost one tube to turn on s
An interesting characteristic of an AC relay is that it buzzes like crazy as the voltage ramps up to the value it needs to fully operate. I assume that the relay contacts are doing that as well which
By the time the relay starts buzzing the AC voltage is probably up to maybe 70% of maximum and the turn on surge is about over. The buzzing contacts then will be shorting across the limiting resistor
There has been a lot of recent discussion on Step Start circuits. Would one of the 'hockey puck' or solid state relays work OK in this application? They are usually available with 25 amp capability a
You might check your ac line voltage (while key down) where the amplifier plugs in. I have seen some pretty low ac line voltages at times. It doesn't take much resistance in the ac line circuit to ca
High grid current with low plate current usually means the output circuit needs heavier coupling to the load. Said another way, the plate load impedance set by the output network is too high. The YU1
Hello to the group, Has anyone in the group ever used solid state relays for controlling the AC input to a power supply for a 1500w amplifier? I recently acquired some really nice 50A @ 480VAC solid
Some hv diodes consist of several 1kv diodes in series. If there were four then it would require a voltage of about 2.8 volts for all of them to conduct. Many Volt Ohm Meters use a 1.5v battery for t
It appears that a new filament transformer will be needed for the 3CX800A7 tubes as they are 13.5vac. If this is the case, then why not use the normal high voltage transformer primary step start circ
Is any rule of thumb to estimate input impedance for a tube/s in GG configuration?. Best regards Guillermo - LU8EYW. _______________________________________________ Amps mailing list Amps@contesting.
If Alpha furnishes the new amplifier with USB interface then anyone trying to use an older computer is screwed. At least with the RS232/serial/comport all users have a way to control the unit. They m
Hi Keith, you know how "thrifty" we are as a group; many of us are still using older computers. It is not so much that I can't afford to buy a new computer as the old one is in place and still workin
Is that like the ROM function (read operators mind)? It is a slow day here! 73, Gerald K5GW In a message dated 9/16/2005 2:13:42 P.M. Central Standard Time, stevengrant98@yahoo.com writes: i would li
It would be very interesting to hear why this might be true!? 73/k5gw In a message dated 9/23/2005 5:01:16 P.M. Central Standard Time, k7fm@teleport.com writes: I have a 6.5 KW 120 volt Onan generato
A common workaround is to cover the white wire end with black tape or heat shrink. This was allowed in the NEC book 25 years ago; not sure about today. The use of four wires can be a problem if the e
Hi Dave, many of our linear amplifiers use capacitor filters in the hv power supply. These type power supplies require peak currents on the order of five to ten times the average current. While #12 w
I have used 5052 material many times in amplifier construction with excellent results. Once I quit worrying about the 6061 vs. 5052 all the perceived problems disappeared! 73, Gerald K5GW In a messag
I don't think this is correct. The k=1.8 or 1.6 or ??? covers this doesn't it? A triode doesn't operate with the plate voltage swinging down to near the grid potential; more like a similar value for
Perhaps 120VAC devices were more prevalent then or the tap arrangement was too complex? Recent amps designed for use with either 120VAC or 240VAC do not appear to share this issue. Anyone know what t
Choke input filter type power supplies require a quite a bit of bleeder current to prevent voltage soaring like you describe. You can find more information about this in your handbook. I suggest you