On 01 Feb 2004 07:05:17 GMT, Ray di Tutto wrote:

"Steve Nosko" wrote in
:

Hmmmmm... Les see... I don't know this rig, but...

No dip.

You say: "The amp can be tuned though, but I only get 50 W HF out..."

I don't know what "tuned through" means Do tell. Is there any
kind of a PEAK in the output power when tuning either the plate tuning
or the plate loading?

Not sure where to go from here, but these two controls, when not
behaving normally, indicate that either there is not a tank circuit
(something is shorted or open). This could be something in the tank
ckt OR the tube.

Getting 50 watts seems to indicate that the plate circuit is NEAR
resonance, so something must be close to right. I'd look @ tube
voltages (Be careful)

Ran out of ideas.

73,

Hi,

tnx for your answer.

I can obtain a very shallow dip in plate current when first tuning at low
power (there is a TUN switch on the TS 820). After that , the instructions
manual indicates to switch to CW mode, switch to xmit and quickly adjust
the plate and load caps while watching the RF out dial. Tune to max power
out. That is when I can get 50 Watts out, with the plate control about
where it should be as per the numbers printed on the dial and the load cap
at about mid-range. Both controls peak quite well.

However, the problem is that there should be twice this power output.
Furthermore, after about 10 seconds, the plates of the 6146Bs start to glow
red. So I guess that all the missing power output is indeed being
generated, but ends up heating the plates.

All of this happens when operating on 20 meters, my favorite band. When
trying to tune on 40 meters, things are much worse.
What has happened a couple of times is that when alternately adjusting the
plate and load caps, they don't actually peak. Instead, I can obtain a
higher and higher power output and higher and higher plate current, until
the rig fuse blows after a few seconds. There must be an oscillation in the
final stage. I will re-check neutralization.

Voltages on the tubes are OK: -60 V on the grids, +247 V on the screens,
+800 V on the plates on SSB, without modulation.

Vy 73 de HB9SLV

Have you tried the basic stuff first, like installing a new pair of
final tubes?

How much plate current are you using, at maxium?
at minimum dip?

Is the antenna within the proper impendance range?
Tried tuning up using a dummy load?

Did this problem happen suddenly?

Doug