I'm not convinced that it's related to the output level. The rough sidetone suggests to me that the problem is somewhere in the 2nd IF/Audio board. The sidetone is generated there by feeding the CW oscillator into the RX IF and letting the product detector do the work. Coincidentally, the ALC control also takes place on this board. It may be a decoupling issue. A good starting point might be to re-cap all of the electrolytic decoupling caps on the board. They are all positively ancient in dog years. Just speculation at this point...
73 -Jim NU0C On Mon, 03 Mar 2014 22:20:36 -0500, Floyd Sense wrote: >Interesting. I'll bet that no two TR7s will behave exactly the same in >this respect since there are several adjustments involved, and they've >probably all been adjusted differently after all these years. I haven't >seen that fuzzy signal problem, but as I said I have my output cranked >back a ways. > >73, Floyd > >On 3/3/2014 9:57 PM, Jim Shorney wrote: >> Thanks for the comments, Floyd. I have noted with my TR-7 that if I get into >> ALC on CW the sidetone starts to sound "rough" and a scope on the carrier >> shows >> what looks like some AM "fuzz" starting to show up on the signal. I was never >> sure if this was a problem or not as the owner's manual does state that >> advancing the carrier control past the point where the light comes on "may >> result in undesirable keying characteristics". I've seen a couple of other >> TR-7s do something similar. I may look into it at some point, but as long as >> I >> stay below ALC illumination everything looks fine. Using even a little ALC to >> "level" the carrier on transmit doesn't sound like a good idea anyay. >> >> 73 >> >> -Jim >> NU0C >> >> >> On Mon, 03 Mar 2014 16:11:24 -0500, Floyd Sense wrote: >> >>> In the "Tweak my peak" thread, NU0C said this: >>> >>> /On CW, definitely operate below the ALC level. The quality of the transmit >>> signal starts to degrade when you go into ALC.// >>> / >>> >>> I decided to take a look at that today, using my Orion II and NaP3 >>> panadapter to examine the TR7 output spectrum as the ALC was varied. My >>> TR7 is setup to put out 100W at the point on the carrier level control just >>> before where the the LED comes on (on 20M). The TR7 was operated into a >>> dummy load and the Orion had no antenna connected and 18 dB of attenuation >>> dialed in so the TR7 signal didn't overdrive the panadapter range. >>> >>> I watched the panadapter display as I rotated the carrier level control >>> from that point to full clockwise. The ALC LED came on at about the 1 >>> o'clock position. The power maxed out at 115 watts. I saw no change in >>> the spurs I saw at all over that range. The strongest spurs were 60 dB >>> down from the carrier. >>> >>> So, it appears, at least on my TR7, that there is no degradation in the CW >>> signal (looking 40 KHz in each direction from the carrier) that is related >>> to ALC action. Maybe if my TR7 were adjusted for maximum output, other >>> factors might cause increased distortion that would appear to be related to >>> the ALC level (but might not be). >>> >>> I checked again on 10M CW (where my max output is set to 80W) and found the >>> same thing to be true (but spurs were 67 dB down). >>> >>> >>> 73, Floyd - K8AC >>> >>> >>> >>> >>> >>> >> -- >> Theres something out of place lets go and poke it with a stick. The >> Doctor, "Amys Choice" >> >> > -- Ham Radio NU0C Lincoln, Nebraska, U.S.S.A. TR7/RV7/R7A/L7, TR6/RV6, T4XC/R4C/L4B, NCL2000, SB104A, R390A, GT550A/RV550A, HyGain 3750, IBM PS/2 - all vintage, all the time! "Give a man a URL, and he will learn for an hour; teach him to Google, and he will learn for a lifetime." HyGain 3750 User's Group - http://groups.yahoo.com/group/HyGain_3750/ http://incolor.inetnebr.com/jshorney http://www.nebraskaghosts.org _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
