** As I understand it, the Y-448 draws slightly more filament current
than a 4-1000A, and therefore has more peak emission - which a good thing
for pulse service.
>I have talked with R. Brandon at EIMAC (CPI) about this. It seems that they
>are 4-1000A and the 4PR1000 tubes are the same.
>The 4PR1000b tubes are taken off the production line of the 4-1000A tubes
>and then they are tested with 30KV on the anode. The voltage is raised
>slowly to condition the tube until it reaches the max. They perhaps go a
>little above the 30KV but that is only speculation on my part. Most of the
>4-1000A tubes that they meet the requirement right off the bat because they
>are rated for plate modulate AM applications with 5500 volts plate voltage
>which translates to 11,000 peak voltage (more than 1/3 of the PR
>rating). He just sent me the newest version of the Care and Feeding of
>Power Grid Tubes which has much more material in it than the old version
>(now 173 pages).
>
>Conditioning is a routine where you slowly increase the voltage until there
>is a flash over or there is a sudden increase in current. The flash over is
>usually due to small pointed or irregular surface feature that the flash
>over evaporates. And then you can try again.
>
>By the way don't use any Triton 4-1000 or 4PR1000 tubes. They have not been
>able to make them reliably. Every new Triton I have tested before they go
>to into service in a linear accelerator has failed due to gas or low
>emission or both. The best tubes are the Amperex made by Covimag in France.
>And they have graphite anodes as well. This instrument has been getting
>over 2 years of continuous service from the Amperex ones. They have even
>switched from the 4PR1000 to 4-1000 tubes. Their plate voltages in the
>power oscillator runs up to 8 or 9 Kv.
>
>One caution about used 4PR1000 tubes. If they are used in pulse
>applications they often can look perfectly good (no brown color on the
>glass envelope) but be low on emission. In some applications they run them
>until they are really flat. I guess that may be because they are often run
>in pairs and the stronger tube can keep things going.
>
>73
>Bill wa4lav
>
>
>
>At 02:22 PM 12/10/2003 -0700, you wrote:
>>I have searched google for details on the diferances between the
>>4pr-1000b (pulse tube) and the basic 4-1000a and have found limited
>>information.
>>
>>My HB 4-1000 amp, GG with 6Kv anode voltage performs well, but just
>>today realised the tube is an Eimac 4pr-1000b....I can just read the
>>faint red print.
>>
>>What "real" difference is realised by using the pulse rated tube and the
>>"standard" 4-1000a ??
>>
>>Also, any experience out there regarding using the National Y448 tube? I
>>have the oportunity to purchase one of those...will they function as
>>plug-and-play replacements to a 4-1000? Reliable?
>>
>>Steve ve6wz.
>>
>>_______________________________________________
>>Amps mailing list
>>Amps@contesting.com
>>http://lists.contesting.com/mailman/listinfo/amps
>
>_______________________________________________
>Amps mailing list
>Amps@contesting.com
>http://lists.contesting.com/mailman/listinfo/amps
>
_______________________________________________
Amps mailing list
Amps@contesting.com
http://lists.contesting.com/mailman/listinfo/amps
|