Problem with Heathkit VHF-1 Seneca

[Glen Zook]

Grid current is over 5 mA which is "perfect" for a
pair of 6146 tubes.  Plenty of drive on both 6 meters
and 2 meters.  The signal is "on frequency" checked
with both a Millen grid dip oscillator and with a
service monitor.

Plate voltage is right at 600 volts under load on 6
meters and slightly higher on 2 meters since not as
much current is being drawn.  This is "spec" for the
Seneca.

The link coupling is as simple as it can get.  There
is a 1 turn variable link with one side going to
ground through a 75 pf maximum variable capacitor and
the other side connected directly to the antenna
connector.  The variable capacitor is at minimum
capacitance (fully open) which represents maximum
load.

On the surface there is nothing wrong!  However, the
transmitter will not "load" to the proper 230 mA plate
current, only to about 60 mA.  On 6 meters the
transmitter operates full normal.

Glen, K9STH


--- Brian Carling <bcarling at CFL.RR.COM> wrote:

Glen, what is the grid current?
 
Are you sure you are getting enough drive?

Also, have you measured the plate voltage under load?







Glen, K9STH

Glen, K9STH

Web sites

http://home.comcast.net/~k9sth
http://home.comcast.net/~zcomco


	
		
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