Drake R4C Receive difficulties - BoatAnchors Forum at eHam.net

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eHam.net Forum : BoatAnchors : Drake R4C Receive difficulties

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Drake R4C Receive difficulties	Reply
by LEEH on November 2, 2009	Mail this to a friend!
I have a Drake R4c that I have recently purchased. I've cleaned it up a bit, replaced all the tubes w/ NOS and cleaned the PTO gears. I wanted to check it out as a receiver without being connected to a xmtr so I used a piece of coax w/RCA plug into the antenna jack, used the shorted plug for the PTO, set it to am, passband in middle, agc off, notch off, RF gain on max and af gain to midpoint. The receiver lights up and I get some static from the speaker but no signals on any band anywhere. Actually, I can't even hear a difference in static with the antenna disconnected I have it on the second floor of a frame house. Could this be a bad tube (I have the originals and can substitute) or am I missing a setting somewhere. If this looks like something requiring a deep repair, I'll send it out but want to make certain, I'm not missing anything or doing something stupid. Thanks for your help

RE: Drake R4C Receive difficulties	Reply
by W5RKL on November 2, 2009	Mail this to a friend!
Did you adjust the front panel Preselector for maximum signal? Each band has a setting marked on the Preselector panel settings. A few other possibilities are as follows: 1, If the noise limiter is not installed, a shorting plug that shorts pins 3 to pin 6 and pins 4 to 7, must be installed in the noise limiter socket. If the shorting plug is not used, short lengths of wire can be used to short pins 3 to 6 and pins 4 to 7. The noise limiter socket is located to the right of the 5 internal heterodyne oscillator crystals. The 5 heterodyne oscillator crystals are located on the top left rear of the chassis. This 7 pin socket is NOT a tube socket! 2. In AM mode, if the AM filter is not installed, a 150 ohm 2 watt resistor is installed in the AM socket. Without the resistor there will be no signals passing to the detector hence no receive signals, regardless of the settings of other front panel controls. Set the MODE switch to SSB and tune around for signal, adjusting the preselector for peak S meter reading with the Preselector pointer in the range of the band switch setting. 3. XTALS front panel switch is set to a position other than "NORM" setting. The XTAL front panel switch selects additional crystals installed into the rear panel crystal sockets (behind rear panel cover square cover). Set the XTALS front panel switch to "NORM". 73s Mike W5RKL

RE: Drake R4C Receive difficulties	Reply
by WX7G on November 2, 2009	Mail this to a friend!
I have had this problem when completely retubing a piece of gear; one of the tubes was defective. As you suggest you might put in the old tubes to begin your troubleshooting.

RE: Drake R4C Receive difficulties	Reply
by W5RKL on November 2, 2009	Mail this to a friend!
One more thing. The Bandpass Tuning control determines the sideband, USB or LSB. Set the bandpass control to the left of center for LSB and to the right of center for USB. Tune in a signal, adjust the Preselector for maximum S meter reading then adjust the Bandpass Tuning, left or right of center depending on the desired sideband, for maximum S meter reading. 73's Mike W5RKL

RE: Drake R4C Receive difficulties	Reply
by LEEH on November 2, 2009	Mail this to a friend!
Good suggestions. I did however try adjusting the preselector but not really getting any reading at all. The shorting plug for the NB is installed and so is the resister for AM. I also tried SSB too without success. However I think I will try reseating the blanker plug. The xtal switch is set to norm and since I had the knobs off for cleaning I double checked to assure it was properly reinstalled. Since there is only one way it can go, I have to assume it is correct and is really pointing to the Normal position. I appreciate the hints. I think I will also try another piece of wire just connected to the center pin only (long wire) and see what happens. 73's Lee

RE: Drake R4C Receive difficulties	Reply
by LEEH on November 2, 2009	Mail this to a friend!
Any suggestions on which tubes could be the issue? Looks like that option is pretty high up on my list. 73's Lee

RE: Drake R4C Receive difficulties	Reply
by LEEH on November 2, 2009	Mail this to a friend!
Yup, tried that - both upper and lower. Actually, I really went out of character and read the manual (not something I would admit in public of course!) I don't seem to be getting any signal at all so I can't tune for maximum.

RE: Drake R4C Receive difficulties	Reply
by W5RKL on November 3, 2009	Mail this to a friend!
Have you tested the tubes yet? Mike

RE: Drake R4C Receive difficulties	Reply
by LEEH on November 3, 2009	Mail this to a friend!
Working on it. I know it isnt the 6ej7's

RE: Drake R4C Receive difficulties	Reply
by K1DA on November 4, 2009	Mail this to a friend!
One shorted plug turns on the PTO LAMP, there is ANOTHER plug for the PTT line which is normally shorted on RX when connected to a T4X series transmitter. Nevertheless the receiver should work on the "ON" position but not on any of the other positions unless the PTT RCA socket is shorted. Make sure THAT plug is shorted and then try to hear the calibrator signal which should be many DB over 9 on the lower bands and at 25 KHZ intervals. It won't work on 160 unless there is a 160 crystal in the "extra crystal" bank despite the bandswitch marking. You have to put the AUX crystal switch into the position where the crystal is installed, AND have the switch on 160. If you have another receiver (don't suggest using a TRANSceiver) see if you can hear the R4C calibrator signal with it. That tells us how much of the radio is probably OK.

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