I once fed my R-4A (the 11 tube version) a premix signal from a stable modern signal source to see exactly that. I don't know which, but the BFO and/or the 5995 Kc LO was drifting at least couple of hundred Hz over the testing period. I personally do not care too much about the PTO drifting as long as it is usable after proper warm up. But carrier/LO/BFO going out of sync between T-4X and R-4A is inconvenient to say the least. I do have a color-matched pair, but they still tend to go separate ways even after hours of warm up. Even with this issue, I have no plan to "upgrade" to T-4XC/R-4C. hi.
73s, Kihwal, K9SUL ----- Original Message ---- From: Garey Barrell <k4...@mindspring.com> To: Larry Mccabe <lmccabe...@aol.com> Cc: "drakelist@zerobeat.net" <drakelist@zerobeat.net> Sent: Thu, January 5, 2012 1:59:37 PM Subject: Re: [Drakelist] r4c pto drift obsevation Larry - That is interesting.... I've never experienced it, as my shack has always been air conditioned. The PTO coil is pretty well sealed, and I wouldn't expect it to be susceptible to humidity. The only other sources would be the BAND oscillator, crystal controlled with a lacquered transformer, the 3rd Mixer LO, also crystal controlled, and the BFO. The BFO is just an 'IF Can' style coil, and would be the most likely suspect. Would be interesting to see which of these oscillators is actually the one(s) moving.!! 73, Garey - K4OAH Glen Allen, VA Drake 2-B, 2-C/2-NT, 4-A, 4-B, C-Line and TR-4/C Service Supplement CDs <www.k4oah.com> Larry Mccabe wrote: > i've noticed some interesting drift characteristics on my r4c. i live in >florida.. shack in the garage.. during the summer months , with 80-90 deg >temps >and high humidity, the r4c drifts approx 50 hz per hour. during the winter >with >50-60 deg temps and reduced humidity the drift is reduced to 10 hz per hour . >in >both cases these measurements were observed after a lengthy warm-up period >using >a digital display counter. i have no internal fan or aux cooling in the radio. >only significant change in the vacinity of the pto is the sherwood audio amp >mod >. temp and humidity obviously a significant factor in dealing with drift. i >know >this is no big revelation.. thought the differences were interesting though. > Larry WA0QHF > > Sent from my iPhone > > _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist _______________________________________________ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
