It sounds like the carrier frequency is not centered in the middle of the two filters.
-------------- Original message -------------- From: Robert Ladden <[EMAIL PROTECTED]> > > Robert Ladden made an utterance to the drakelist gang > ---------------------------------------------------------------------- > Hello again, > > After more testing, I must be way off. Even though I have the carrier > completely suppressed now, I discovered that when I tune I have much more > plate current (150ma) and output power on LSB than USB. The voice is > intelligible on both LSB and USB, but LSB sounds "glassy", USB sounding > more rich with more low voice tones. > > So I must not be balanced, but anything else results in a carrier (about 40 > output watts on LSB on the watt meter). > > Do I have a major problem? A bad filter? Or do I just try some more before > shipping it out for someone smarter than me to fix? > > Thanks and 73, > Bob Ladden WA3WQB > > > > >Robert Ladden made an utterance to the drakelist gang > >---------------------------------------------------------------------- > >Hello all, > > > >I just got my C-Line out of the closet after 25+ years of storage. They > >seem to work OK. I've been playing with them with a dummy load (antenna > >not up yet) and the one obvious problem I had is the carrier balance. The > >watt meter showed power going out on SSB LSB with no speech. The > >instructions for adjusting the carrier balance in the manual is not too > >good, so I searched and found K2CU's wonderful instructions, which I > >pasted below for safe keeping. > > > >I found that I had to turn C6 completely clockwise to bring down the > >carrier signal when tuned in on the receiver. But it does pass K2CU's > >balance test procedure. I can eliminate the carrier completely with C6 > >(fully clockwise) and R21 (somewhere in the middle, it turns a lot). > > > >C17 did not seem to do much. It may have improved the voice quality. At > >first LSB sounded bad. After really turning C17 a lot, it seems to be the > >same as USB. > > > >I have yet to get the rig on the air and test with a real person. But I am > >concerned that I needed to turn C6 to its extreme. I also note that the > >carrier is completely gone. I also discovered that the spot signal is > >gone. It is just a teeny noise on LSB and a very very weak carrier on USB. > >Not really usable. It did generate a signal before I did all this. > > > >So did I do good? Or does this rig need a lot more tweaking? > > > >73, > >Bob Ladden WA3WQB > > > > > >K2CU's original message follows: > > > >RE: [drakelist] T-4XC Carrier Balance Question > >Robert Schenck > >Mon, 29 Dec 2003 05:09:54 -0800 > > > >HI Mike, > > > >Welcome to the world of the Drake equipment! > > > >There ar ethree adjustkments that you ahev to do to correctly balance the > >carrier. > >They are C6, Carrier frequency trim, R21, carrier balance, and C17 Carrier > >balance/phase. You should firest check that the carrier frequency trim is > >correct. > >the idea with this adjustment is to place the carrier on the same point of > >each > >sideband filter skirt. that is, to be just as far down on the lower skirt > >of the USB > >filter as you are on the upper skirt of the LSB filter. This is usually > >done by > >deliberatly unbalancing the modulator so that carrier leaks through. You > >measure the > >amplitude of the carrier on a test receiver and compare the level between > >the USB > >position of the T4X SSB switch and the LSB poisition. The carrier > >amplitude should be > >close to the same as posible. BY adjusting the carrier frequency trim, you > >set the > >carrier to the correct frequency for both modes. I would only mess with > >this if there > >is more than an S unit difference..... > > > >Then you can adjust the carrier balance pot, R21 for minimum carrier. you > >have to also > >adjust C17 the carrier pahse. Note that you should check for balance in > >both USB and > >LSB modes. you will have to adjust the trimmer, C17, for optimum carrier > >null for noth > >sideband modes, and to has to deal with the slight difference in reactance > >reflected > >back from the selected filter. Now, if you only operate 20 Mtr USB, for > >example, you > >could just tweak it for USB. Same is true for LSB only on a l;ower band. > >But, it is > >best to balance it for each mode. > > > >Hope this helps. > > > >73's > > > >Rob K2CU > >---------------------------------------------------------------------- > >Submissions: [email protected] > >Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body > >Hopelessly Lost: [EMAIL PROTECTED] - help in body of message > >Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net > >---------------------------------------------------------------------- > > ---------------------------------------------------------------------- > Submissions: [email protected] > Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body > Hopelessly Lost: [EMAIL PROTECTED] - help in body of message > Zerobeat Web Page: www.zerobeat.net - sponsored by www.tlchost.net > ----------------------------------------------------------------------
