Jim - I've found with a lot of the A's and B's that the calibrator does run out of steam on the higher bands. I haven't found one yet that gives over S-9 (or even S-7) on 10. I can't recall what the C-line was like. Of course, the calibrator works by outputting harmonics of 25 kHz and the higher you go, the lower the strength.
Having said that, it does sound as if you have a problem in the receiver. It is more than the RF amplifier that can reduce received signal strength - low output of mixers can also degrade the signal strength. The major mixer in the receiver that has an effect on the transmitter is the "pre-mixer" V8 (6HS6). I've seen these tubes go soft. Try swapping with V2 to see if there's a difference. You can also try swapping with V8 in the transmitter. Be sure you keep track of which tube was where! If you don't see any difference, you'll have to break out a scope and start looking at signal levels. The 10m oscillator output shouldn't be radically different from the others. I'm forgetting what the voltage levels should be from the band oscillator and premixer, but I'm sure someone else will check-in with those values. Good luck & 73... Steve Wedge, W1ES/4 To be is to do - Socrates To do is to be - Plato Do be do be do. - Sinatra All my computers have my signature with various pearls of wisdom appended thereto. From: J G Sent: Wednesday, November 09, 2011 5:29 PM To: drakelist@zerobeat.net Subject: [Drakelist] R-4B low sensitivity low output on 10 meters 28 MHZ Hi, Now that 10 is alive and well, I decided to put the B line (T-4XB, R-4B) on 10. Hasn't been there in a long time. The low sensitivity part: The R-4B has low sensitivity on 10. I do not recall that from 20 some years ago when I was last on 10 with it. Using the R-4B to control, the calibrator will get an S meter reading of about S5. Using the T-4XB to control the calibrator will yield an S8 reading. This was done at 28.5, and this is after adjusting the 4 trimmers for 28.0. I notice the same results using the cw range (28.0 - 28.5) crystal at both 28.0 and at 28.5. I do have 28.0 and 28.5 crystals in both the R-4B and the T-4XB. A low S meter reading is also obtained using the 24.5 meg crystal that I have in an accessory socket of the R-4B (I do not have one for the T-4XB). As expected, "real signals" are louder using the T-4XB to control. This situation did exist on 15 meters, but adjusting the 21 trimmers did take care of that. The low output part: Using the R-4B to control, power out is low. About the best it can do is 30 watts with .16 plate current. Using the T-4XB to control (transceive), about 75 watts with .26 plate current (gain full open) Using the SEPARATE position about 110 watts with .32 plate current (gain at a bit less than 12:00) Power readings as per wattmeter in C-4, so may not be accurate, but they are relative. I think the low sensitivity and low output problems are related, but I am not sure why the output would vary so much between the T-4XB as the transceive control and the separate control. Any ideas welcomed. Thank you, Jim -------------------------------------------------------------------------------- _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
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