[EMAIL PROTECTED] made an utterance to the drakelist gang ---------------------------------------------------------------------- Hi all,
I don't remember anyone posting a fix for my TR-4 problem. The rig works great on 80 through 15 meters but on 10 meters (all sub bands on 10) received and transmit signals sound like AC hum or garble. Has anyone run into this? Second proble: I note that when I transmit the reciever does not come back right away. The S-Meter goes full scale and sometimes after a few moments the receive will come back. It is variable in that sometimes it will hesitate only a second or two, and sometimes it take much longer. I tried various VOX adjustments with no effect. I am wondering if my problem lyes in the VOX/TR circuit or just a sticky (dirty) relay. If during this time I hit the transmit button, it transmits just fine, but when I let up, it hangs. 73, Mike - K7OV -------------- Original message ---------------------- From: F3WT <[EMAIL PROTECTED]> > > F3WT <[EMAIL PROTECTED]> made an utterance to the drakelist gang > ---------------------------------------------------------------------- > Garey, Ron, > > Thanks a lot for your answers - very interesting! > 73, Pierre - F3WT > > Le 20 déc. 05 à 23:30, Garey Barrell a écrit : > > > > > Garey Barrell <[EMAIL PROTECTED]> made an utterance to the > > drakelist gang > > ---------------------------------------------------------------------- > > Pierre - > > > > There probably isn't "one" good answer! On the surface, it seems > > that crystals were/are less expensive than good filters. Early > > Drake filters were only 4 pole, probably costing considerably less > > than mechanical filters at the time, and had to be upgraded to 8 > > poles in the later TR-4s and T-4XB/C to meet more stringent FCC > > signal purity requirements. > > > > Two Filter scheme (Drake) - > > > > 1. Only one crystal required, but two "different" 9 MHz (TR-3/4) > > or 5.645 MHz (T-4any) filters. > > 2. Suppressed carrier frequency is the same, regardless of USB or > > LSB. > > 3. CW is obtained just by shifting the oscillator "somewhere" > > within the passband of one of the filters, the shift resulting in > > the "CW transceive" offset. Precise shift not critical, allowing > > simple switched capacitor shift rather than another crystal. > > 4. Allows transceive with single patch cable between units. > > > > > > One Filter scheme (Collins) - > > > > 1. Two crystals required, plus a third for CW offset (probably > > because of low frequency), but only one 455 kHz filter. > > 2. PTO must also be shifted "exactly" the same amount as the > > carrier oscillator to keep suppressed carrier frequency the same on > > USB or LSB. > > 3. Requires patching of carrier oscillator and PTO between T and > > R, complicating switching between transceive and separate control. > > > > Drake "phase-locked" the carrier oscillator (T) and 2nd Converter > > LO (R) in the C Line because the two crystal oscillators didn't > > "track" perfectly over temperature variation in the earlier > > models. (Color coded crystals were an "interim" fix in the late A > > and B Lines.) This provided stable transceive without the > > switching complication of the Collins system. > > > > Probably other considerations that I'm not thinking of! :-) > > > > 73, Garey - K4OAH > > Atlanta > > > > Drake C-Line Service Manual > > <http://www.k4oah.com> > > > > > > > > F3WT wrote: > > > >> Hi Garey, > >> > >> Very clear explanation below! > >> > >> I have a related question I was wondering about for a while: > >> > >> Why were TR4s - and others by he way - designed with 2 sideband > >> filters and 1 Xtal ( 9MHz ) rather than todays set of 1 > >> sidebandfilter and 2 Xtals (SSB) or 3 including CW? > >> Was it a problem then shifting VFO without loosing stability? > >> 73, Pierre - F3WT > >> > > ---------------------------------------------------------------------- > > 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 > ---------------------------------------------------------------------- ---------------------------------------------------------------------- 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 ----------------------------------------------------------------------
