[Kenwood] TL-922 question

Thu Dec 8 11:34:39 EST 2011

On 8 Dec 2011 at 1:44, rb wrote:
> How are you measuring the drive power?
>> 800v on FT-101zd x approx 200 ma

That is 160 watts INPUT, not output. As someone else mentioned here, 
the FT-101ZD is rated at 180 watts INPUT, which, with new 6146Bs 
provides 100 watts OUTPUT from 40 through 15, about 110 watts on 80, 
and 90 watts or so on 10. 
At 160 watts input, your output is about 90 watts, maybe less.
> = 150 watts on FT-101zd indicator

>From the above, either your FT-101ZD output indicator is not 
calibrated properly, or you are feeding into a high-impedance load 
which will indicate more power output than you are actually 
producing. 
To calibrate it "closely enough", feed the FT-101ZD into a 50 ohm 
dummy load, load up to 180 watts input, and adjust the PO CAL pot on 
the back so it reads 100 watts on 40 meters. That will be close 
enough.
> Are you using ALC (correctly)? 
>> As far as I know. I'm using the FT-101zd ALC out.

To test, disconnect any ALC connection between the FT-101ZD and the 
amp. Then load up on CW.
> Did it EVER put out the rated power for you? 
>> When I was driving it with my TS-430S I did have more power. I
> don't have the TS-420S here at this QTH. I didn't really look at
> this as an issue until this time with the FT-101zd. Seems like
> everyone was having a hard time hearing me, and I did some
> calculations.

The difference at the RECEIVE end between 500 watts output and 1500 
would be about 2 "S" units. Are you certain you are not having some 
sort of problem with your antenna system? Perhaps your balun has 
failed? (Shorted). It would be very difficult to drive any sort of 
power into a shorted load. Perhaps one leg of your feedline is 
disconnected. Something is wrong in the antenna system.

> How are you tuning the amp?
>> I do it with the FT-101zd first. Get reflected power down to zero,
> at 150 watts.

What do you mean "reflected power down to zero" ? Do you mean between 
the ZD and the amp? If this is true, how are you doing this? With a 2 
foot piece of cable and no tuner, and with the TL-922 set on the same 
band as your ZD, there should be essentially NO SWR between the two 
anyway. What are you adjusting to reduce the SWR to zero between the 
two? The only way I know of is to adjust the grid circuit tuning of 
the TL-922, which you should not have to do but once when first 
setting it up, and even then, only if it has been damaged or drifted 
off over a period of years. What is the SWR BEFORE you attempt to 
"fix" it? Even an SWR of 2:1 would not make a significant difference 
in the power presented to the TL-922. Anything 2:1 or less would be 
made up by the output network of the ZD.
> With the amp on, I quickly tune PLATE and LOAD for max
> on power out. This gives me about 500 watts on tuner indicated
> (cw=2200v; 2200 x 215ma = 500 watts <approx>)

That is INPUT not OUTPUT!!!!!!!!
> How are you measuring the output?

Yes. Exactly. How are you measuring output
>> With the tuner indicator. Has standard forward/reflected.

Does it have a "Power" choice, or only forward and reflected? If only 
forward and reflected, then you cannot tell what your power output 
is.
If some sort of power output indicator is REALLY showing you 500 
watts, that almost certainly indicates some sort of problem with your 
antenna system. At 500 watts INPUT to the amp, the MOST you should be 
reading for output is about 300 watts IFF your balun and antenna 
really are what you think they are. And every power output reading 
device I have ever heard of is only accurate if the impedance on both 
ends is exactly 50 ohms. 
> One thing I note: I bought this amp, maybe 10 yrs back. It was
> used. I brought in home and used it not very often. I've been off
> the air for maybe six yrs. The finals tubes are not at all new. 

Well, that could be part of the problem all right. What brand are the 
tubes? However, with 3-500Zs, I am not sure they go bad in that way.
I think you have a bunch of other problems to look at and fix before 
we look at the tubes.
At this point, I am almost certain you are having a major problem 
with your antenna system, NOT with the ZD or the amp.
To check, get a 2KW 50 ohm dummy load and go completely through the 
ZD/AMP setup. I'll bet you find completely different readings.
Ken Gordon W7EKB