[Amps] Building or Buying a Tuned Input Network

[Tony King - W4ZT]

I agree totally with Bob about the dangers of running the GS-35B at 
voltages above 3800  Volts.  Though it has been done, it is a very risky 
cloud to fly in and not where I would want to go.  There are plenty of 
tube failures attributed to running the voltage too high.  Running Ep at 
3800 will reduce the Ip, HF efficiency will be up a bit and drive will 
be slightly less. All in all, very satisfactory for a hundred buck tube!

73, Tony W4ZT

w6ah at comcast.net wrote:
> Drive power relates to output indirectly as anode voltage, biasing and 
> operating frequency all influence output power. With 3000 volts on the 
> plate OZ1DPR obtained the following
>  
> 10 watts drive,  400 mils of plate current, 300 watts out
> 50 watts drive,  700 mils of plate current, 800 watts out
> 100 watts drive,  950 mils of plate current, 1550 watts out
>  
> The above figures are for 6 meters with a biasing of 30 volts. Though 
> the recommended plate voltage is 3000 volts the tube has a pulse rating 
> of 6000 volts. Many hams are running them at higher voltages some as 
> high as 4500 volts. From what I can deduce from annecdotal data running 
> this tube beyond 3800 volts increases the risk of arc-over, with 
> resultant grid damage, substantially.
>  
> Running this tube on HF should yield an increase of 5 to 10 perent in 
> efficiency from the numbers stated above.
>  
> 73s
>  
> Bob W6AH
>  
> 
>     -------------- Original message --------------
>     From: Bill Turner <dezrat1242 at ispwest.com>
> 
>      > ORIGINAL MESSAGE:
>      >
>      > At 09:14 PM 1/22/2006, Tony King - W4ZT wrote:
>      >
>      > >I hand made a board of my own (had my own nice 5 amp contact DPDT
>      > >relays, Arco trimmers and cores and did essentially the same thing
>      > >but I did leave larger pads to allow for the trimmers
>      > > .
>      >
>      >
>      > ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>      >
>      > Boy are you thorough! Nice work.
>      >
>      > Changing the topic slightly, how much drive does a GS-35b need for
>      > 1500 watts output? It's probably on the web somewhere but I've
>     looked
>      > and can't find it. The comparison chart between it and the 8877
>     shows
>      > a ~2dB difference in gain but no actual drive numbers. I could
>     figure
>      > it in reverse but I'd like to hear from someone with actual
>     experience.
>      >
>      > 73, Bill W6WRT