Recently got my Heathkit DX-40 working, and aquired a Johnson
T/R switch to get a 50 station back on the air...Two questions that
I'm hopeful one of the group will be able to help me with...# 1 the
Heath DX-40 has great output, but when loaded, and keyibng on CW, the
plate current always drops about 15 to 20 ma...in other words if you
key it, it will go up to 125 ma, and then drop down to 110 ma or so
almost immeciately, with a corresponding drop in power as indicated
on an external wattmeter....plate voltage on the final DOES NOTdrop as
current does.
#2..The Johnson T/R switch works great, and all voltages are right on
but I don't think I've ever seen a piece of equipment with two tubes
run that HOT...is that normal...Appreciate any ideas and opinions...
Thanks...Bob

Bob,

What's happening to the grid current when the plate current
falls off? You could be losing some of your drive due to a
bad component or weak tube in the driver stage. It's worth
a look anyway.

Regarding the EFJ T/R switch, their manual states that it's
normal for the unit to run hot.

73,
Dean K5DH

In article ,
says...

Recently got my Heathkit DX-40 working, and aquired a Johnson
T/R switch to get a 50 station back on the air...Two questions that
I'm hopeful one of the group will be able to help me with...# 1 the
Heath DX-40 has great output, but when loaded, and keyibng on CW, the
plate current always drops about 15 to 20 ma...in other words if you
key it, it will go up to 125 ma, and then drop down to 110 ma or so
almost immeciately, with a corresponding drop in power as indicated
on an external wattmeter....plate voltage on the final DOES NOTdrop as
current does.
#2..The Johnson T/R switch works great, and all voltages are right on
but I don't think I've ever seen a piece of equipment with two tubes
run that HOT...is that normal...Appreciate any ideas and opinions...
Thanks...Bob

Time for a new 6146.

73
Hugo

"robco (ns)" wrote in message
...
Recently got my Heathkit DX-40 working, and aquired a Johnson
T/R switch to get a 50 station back on the air...Two questions that
I'm hopeful one of the group will be able to help me with...# 1 the
Heath DX-40 has great output, but when loaded, and keyibng on CW, the
plate current always drops about 15 to 20 ma...in other words if you
key it, it will go up to 125 ma, and then drop down to 110 ma or so
almost immeciately, with a corresponding drop in power as indicated
on an external wattmeter....plate voltage on the final DOES NOTdrop as
current does.
#2..The Johnson T/R switch works great, and all voltages are right on
but I don't think I've ever seen a piece of equipment with two tubes
run that HOT...is that normal...Appreciate any ideas and opinions...
Thanks...Bob

ns wrote:
Recently got my Heathkit DX-40 working, and aquired a Johnson
T/R switch to get a 50 station back on the air...Two questions that
I'm hopeful one of the group will be able to help me with...# 1 the
Heath DX-40 has great output, but when loaded, and keyibng on CW, the
plate current always drops about 15 to 20 ma...snip

You might want to check the screen dropping resistor for the 6146 -
any discoloration or cracking?
Most likely, the problem will go away with a new final installed.

73,
Ed Knobloch