[Drakelist] T4XC problem
hello chaps. I have a problem with my Drake 4 line and would appreciate some assistance or ideas. I have a R4C and T4XC, the rx is good and the R4C appears to work normally but the transmitter will not put out any power and when I place the transceive switch over to the XMTR position the audio goes all warbly - almost auroral hi. The Transmitter will not put out any power at all, I get a small lift on the meter when I initially tune but that soon goes off and I cannot replicate it. There appears to be no difference on the recovered 'Warbly' audio when I switch between LSB USB although the PTO does work and appears to tune the transmitter up and down the band ok. If I attempt to tune or spot then the tx relay chatters constantly with no discernable movement on the meter. This also does this when I try to tune up. Prior to being mothballed for a couple of months it all worked FB. The only other change is that I ordered a new set of connecting cables when I sold my other 4line. The cables all check out OK and I have repeatedly checked the manual re connections with to no effect. I wonder if anyone has had a similar problem with any of their Drake equipment. I would be very grateful of any pointers or help Kind regards, 73 Chris M5LRO ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
[Drakelist] T4XC Problem
I have a T4XC in excellent condition that has developed a problem. I was operating a few weeks ago and notice the transmitter had moved to transmit and I had not keyed the transmitter.Before I could determine the issue, the fuse in the AC-4 blew.I have replaced the fuse and with all connections removed except a dummy load, after about 15 seconds of warm up, the relay clicks to transmit and the plate current starts to climb.I have replaced the vox,and driver tubes with no change in conditions.Any suggestions?ThanksTerry ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T4XC Problem
hi Terry, I hope your finals are OK, maybe you caught it fast enough, or the fuse blew quickly. Sounds like the bias supply has a problem, most likely the filter cap, which may have blown a diode. You lost bias, which affects the PTT ckt and keeps the finals cutoff. If you lose bias it does just what you saw, and puts the finals into full conduction, melting them down. Don't try to power again it up until you rebuild the AC-4, the kit from Heathkit Shop is a good way t do it, but at least get in there and disconnect the present caps and fit some new smaller physically ones in there, for all sections. 73, Al, W8UT www.boatanchors.org www.hammarlund.info There is nothing -- absolutely nothing -- half so much worth doing as simply messing about in boats Ratty, to Mole On 4/18/2011 11:27 AM, Terry Wilkin wrote: I have a T4XC in excellent condition that has developed a problem. I was operating a few weeks ago and notice the transmitter had moved to transmit and I had not keyed the transmitter. Before I could determine the issue, the fuse in the AC-4 blew. I have replaced the fuse and with all connections removed except a dummy load, after about 15 seconds of warm up, the relay clicks to transmit and the plate current starts to climb. I have replaced the vox,and driver tubes with no change in conditions. Any suggestions? Thanks Terry ___ 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
Re: [Drakelist] T4XC Problem
Terry, Have you rebuilt the AC4?? Sounds like the infamous bias cap failure to me. 73, Don, WB5HAK___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T4XC Problem
Hi Terry, check the bias section, no need to get a new supply. Drop H-K Shop a note, maybe he'll send you a new cap. You can disconnect it from the xmtr, short 2 pins on the connector (can't remember which ones, and don't have a skem handy), and you can check no-load voltages. It's possible the bias adj. pot is bad, IIRC, the kit doesn't include that. 73, Al, W8UT www.boatanchors.org www.hammarlund.info There is nothing -- absolutely nothing -- half so much worth doing as simply messing about in boats Ratty, to Mole On 4/18/2011 1:18 PM, Terry Wilkin wrote: Thanks Al. I believe it was caught early in the process so the finals should be OK. The PS was rebuilt using the Heathkit mod and lasted about 2 hours. I will look for another supply. Thanks Terry ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
Re: [Drakelist] T4XC Problem
Terry - Amost certainly failure of BIAS supply in AC-4. Suggest AC-4R kit from The Heathkit Shop. 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 Terry Wilkin wrote: I have a T4XC in excellent condition that has developed a problem. I was operating a few weeks ago and notice the transmitter had moved to transmit and I had not keyed the transmitter. Before I could determine the issue, the fuse in the AC-4 blew. I have replaced the fuse and with all connections removed except a dummy load, after about 15 seconds of warm up, the relay clicks to transmit and the plate current starts to climb. I have replaced the vox,and driver tubes with no change in conditions. Any suggestions? Thanks Terry ___ Drakelist mailing list Drakelist@zerobeat.net http://mailman.zerobeat.net/mailman/listinfo/drakelist
