km1h @ juno.com
Mon, 13 Oct 1997 17:25:16 EDT
On Mon, 13 Oct 1997 14:49:29 -0400 "George M. Roberts" <email@example.com>
>On a SB200 being driven by a Kenwood TS520S I get the following
>readings on 40 meters. The amp is being run off a 120 volt
>line. Plate mils 60 at rest.
It should be 90ma
No-load high voltage is
>2300 volts. Under load it drops to 1900
Thats about right for a 120V line.
Max grid 320 mils and plate
>is 350 mils under load.
Are both tubes lit? Also check that both 33 Ohm resistors and both 200pf
caps at the grids are good. A bad tube will blow the resistor and those
caps sometimes cook also.
With good tubes the grid current will peak right at midscale and the
plate current will be 600-700ma. With 100W of drive power out on 40M will
be around 700W or a bit more on a 240VAC line.
Cannot drive it further without exceeding
>capacity of the exciter, which should be putting out 100 watts at this
>time. I do not have a wattmeter.
Time to get one.
>Are tubes soft?
Very possible. I have both new and full output used ones available.
Private E-Mail if you are interested.
>Is line voltage soft? I can switch to a 220 line which is
>available in the shack.
That will cut down on the sag and give you another 50-100W.
If you plan to use on 10/12M check the parasitic suppressor resistor
values. If they are over 20% high replace them.
GL Carl KM1H
>Thanks for assistance. 73
>FAQ on WWW: http://www.contesting.com/ampfaq.html
>Administrative requests: amps-REQUEST@contesting.com
FAQ on WWW: http://www.contesting.com/ampfaq.html
Administrative requests: amps-REQUEST@contesting.com