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W3UTD
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« on: February 04, 2010, 06:19:20 PM » |
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Finishing up my restoration, got output on all bands, XTAL and VFO. Now I'm running through the adjustments, and specifically the VFO Keyer adjustment.
The manual says to couple the receiver to the VFO with the TX set to CW by unkeyed. OK I did that.
Then Adjust R39 CCW until VFO is received ... adjust R39 CW until VFO signal stops.
But adjusting R39 doesn't do anything, I can hear the VFO signal on the receiver no matter what the setting is.
Any ideas?
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WQ9E
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« Reply #1 on: February 04, 2010, 06:47:49 PM » |
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Do you have a CW key plugged into the jack? It is a self shorting type so without an open key plugged in the oscillator will be keyed.
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W3UTD
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« Reply #2 on: February 04, 2010, 09:35:30 PM » |
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yes, there's a key in it
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WQ9E
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« Reply #3 on: February 04, 2010, 09:52:21 PM » |
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Check your voltages on the keyer tube, pin 2 in particular. The keyer tube itself could be the problem or a problem with the bias supply. Check that you have around -56 volts on the "hot" end of R-39.
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W3UTD
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« Reply #4 on: February 04, 2010, 10:47:44 PM » |
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OK .... Operate in the CW position, Key inserted
Hot side of R39 -66v Key Open, -56 v Key closed
12AU7A (a new tube, tests good)
Pin Key Open Key Closed
1 0v 0v
2 -44v -36v
3 -32v +15v
4 0v 0v
5 0v 0v
6 +348v +319v
7 -54v 0v
8 -32v +16v
9 0v 0v
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W3UTD
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« Reply #5 on: February 05, 2010, 07:32:08 AM » |
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Pin 1, no voltage on one of the the plates?
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WQ9E
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« Reply #6 on: February 05, 2010, 07:46:47 AM » |
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Measure pin 1 resistance to ground and see what you find.
Has any rewiring been done around the crystal/vfo switch?
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W3UTD
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« Reply #7 on: February 05, 2010, 10:02:13 AM » |
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12AU7, Pin 1 to ground, 23K ohms
I'll check the wiring on the switch later today.
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WQ9E
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« Reply #8 on: February 05, 2010, 10:09:16 AM » |
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If the switch looks good pull the top cover of the VFO and check the 6AU6 tube pin resistance.
Pin 1 should show about 123K to ground or around 100K to pin 1 of your keyer tube. Pin 7 of the VFO tube should show near infinity to ground.
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W3UTD
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« Reply #9 on: February 05, 2010, 01:31:34 PM » |
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The switch appears to be wired correctly at least.
Testing
6AU6, Pin 1 to ground = 54K
6AU6, Pin 1 to 12AU7A, Pin 1 = 72K
BUT, 6AU6, Pin 7, shows continuity with ground
I did re-test 6AU6 and it is very weak
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WQ9E
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« Reply #10 on: February 05, 2010, 02:05:44 PM » |
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If pin 7 is grounded then the 6AU6 is going to oscillate. Switch your control switch to the crystal 1 position and recheck. If still grounded then either C20 is shorted or there is a wiring issue. If it no longer shows continuity to ground then check the key and keying line to find the problem. At minimum, the cathode should be 800K above ground with the key up.
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W3UTD
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« Reply #11 on: February 05, 2010, 02:11:01 PM » |
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in XTAL1 (or 2) Pin 7 to ground shows no connection. I'll trace the keying line and look at the key
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sndtubes
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« Reply #12 on: February 11, 2010, 11:35:20 AM » |
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I just refurbed my Ranger (made only minor mods) and interestingly enough, I'm having the same problem with mine. So, if you fix yours, please let us all know what you found. I haven't started making measurements yet.
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ke7trp
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« Reply #13 on: February 11, 2010, 06:19:02 PM » |
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I have had this problem on two rangers. On the first, The POT was bad. I overlooked this for about a week before ripping it out and checking it. Sure enough. The pot was toast. I replaced it with one from ebay parts guy. Worked perfect.. Just dont put the back cover screws in.. This needs to be set on a FULLY warm radio.. Otherwise, When its real hot, You wont get your RX back and you will be frusterated.
The last one that had this problem, turned out to be the mode switch. There was some kind of wiring change to it. I think it might be even in the manual. I really cant remember what it was or why you changed that wire but this was the problem.
C
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sndtubes
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« Reply #14 on: February 15, 2010, 03:44:14 AM » |
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Check the polarity of the electrolytic in the bias supply. Make sure that the POSITIVE end is grounded. That was the problem in mine (caused by ME, of course)
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W3UTD
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« Reply #15 on: February 15, 2010, 10:05:58 AM » |
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Still nothing. I checked the Cap, is it positive to ground.
I must have some switch wiring issues which I haven't found yet.
For example, when running on XT1 or 2, switching from Phone to Standby works as I would expect. But in VFO the relay doesn't kick in, VFO and Zero positions behave the same way, and in VFO mode, switching from Phone to Standby makes no difference.
I have found some audio mods that were done. perhaps some other mods were done which I haven't discovered yet. Ah well, something to keep me busy!
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sndtubes
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« Reply #16 on: February 15, 2010, 10:52:50 AM » |
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Sounds like someone installed a PTT mod as I don't think these were ever factory. Maybe they wired it up wrong? (like I'm about to in mine...I'm sure I'll screw it up).
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ke7trp
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« Reply #17 on: February 15, 2010, 12:44:49 PM » |
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Yours is going to be like my second one. The wires on the switch where changed. Read through the manual to find out what I mean
C
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