Are you saying that we should always tune a grid-driven tetrode linear amp for the maximum screen current allowed by the manufacturer? Well, that would have been 30 or 40 mA on my homebrew AB1 grid-d
FYI, here was my post to the Collins reflector that prompted that reply. What do you think? "There is a lot of misinformation out there about screen current. But it's the most important indication of
When I ran a pair of 4CX250B's on Two Meters, I tuned the Amp for identical Screen Current, within Tube Limits. 73, Dick, W1KSZ _______________________________________________ Amps mailing list Amps@
Are you saying that we should always tune a grid-driven tetrode linear amp for the maximum screen current allowed by the manufacturer? "Always" is so restrictive. 80% of maxium allowed is sufficient
When I ran a pair of 4CX250B's on Two Meters, I tuned the Amp for identical Screen Current, within Tube Limits. 73, Dick, W1KSZ Same here. Don W4DNR _______________________________________________ A
Maximum allowable screen current is not the correct way. You tune for a screen current PEAK and then use the load control to reach a maximum RF output while keeping the screen current within limits,
I don't care for that JI answer since grid driven tetrodes are almost always run in AB1 where there is no grid current and in AB2 there is only a flicker of current on peaks but a lot more IMD. Tunin
Tuning a tetrode amplifier for screen current maximum is correct. Tuning for the maximum screen current allowed by the manufacturer might be wrong if you like to stay within legal limit and use a lar
The tuning procedure for a 100MHZ 35KW FM Transmitter with a 4CX20,000 tetrode is to tune the loading and tuning for a screen current peak. The tuning is so broad that you can't see the plate dip but
A little clarification is in order here: You tune the PLATE tune control for a peak in screen current the same way as you would dip the plate current. The screen current is much more sensitive than t
Carl is correct. In the 4CX1000a the spec sheet calls for 35 ma screen current in typical AB1 service. The screen dissipation is 12w, and at the rated 325v, that would be 36 ma! Of course the duty cy
On 1/27/2015 9:26 PM, Carl wrote: I don't care for that JI answer since grid driven tetrodes are almost always run in AB1 where there is no grid current and in AB2 there is only a flicker of current
I don't know about 'knowledgeable', but screen current goes negative when more electrons are emitted from the screen than are captured by it. They go the plate. In a pentode, the interposed grounded
Under the assumption that the guys who designed and built amplifiers for sale knew pretty well what they were doing, it might be a good idea to simply look into the user manuals of some tetrode ampli
Since the screen is the weak link in the NCL-2000 I don't run mine or customers beyond 15-20ma in the SSB position for the pair and if the PO is a bit lower than the usual 1200W key down it not enoug
Last week I read with interest the discussion here. There were numerous replies, each with a bit of good information. Gary, K4FMX, nailed it spot on, with this explanation reproduced here. This agree
Sorry to be arriving late to this discussion. Gary's explanation is very nearly there... but only for readers who already understand the need to re-peak the screen current with each small change in l
There certainly is nothing new about the proper tuning procedure for a tetrode. The following was taken from the 1963 National NCL-2000 manual who also had plenty of prior experience building militar