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Author Topic: Drake R-4B problems  (Read 1814 times)
KD5PLV
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« on: October 14, 2001, 10:45:12 AM »

I own a Drake R-4B along with a T-4XC transmitter and MS-4 power supply. I have had no luck trying to get it working on receive, which is all I am worried about for the time being until I upgrade from tech. I get nothing but noise all the way across the dial on AM and SSB. The S-Meter doesn't even move. I have tried it with a 10 meter Hamstick and a long wire cut for 10 meters, both run though a MFJ-949E tuner, and still nothing. Any help is greatly appreciated.

73,
KD5PLV
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W9PMZ
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« Reply #1 on: October 14, 2001, 11:54:26 AM »

This happened to me on a R4A, there is a slide switch on the side (at least a R4A, don't know about a R4B).  It has to be in the forward position, otherwise it could be trying for a fixed frequency.
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KD5PLV
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« Reply #2 on: October 14, 2001, 12:16:01 PM »

The previous owner of the rig had that switch fixed to VFO, as there are no additional crystals in the rig. So thats not the problem.
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K3UOD
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« Reply #3 on: October 14, 2001, 09:48:07 PM »

If the switch is worn out (as mine was) it could still be the problem, even if the metal strap is in place to hold it in the VFO position.

Have you tried other bands?  You could have a bad 10M crystal.

Do you have an accessory crystal position selected?  The XTAL switch should be in the NORM position.  The supplied crystal covers 28.5-29.0 MHz; most of the activity is 28.3-28.5 MHz (though when the band is open stations will be everywhere).

Have you peaked the preselector control?

If you don't have a manual you can download one here:  http://ftp://bama.sbc.edu/downloads/drake/r4b/

The R4B is one of the greatest receivers ever built.  Terrific AGC action, selectivity and audio.  Definitely worth the effort to get it working.

Good luck.

Jerry
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KR4BD
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« Reply #4 on: October 15, 2001, 12:15:37 AM »

It is possible that the bandswitch is worn out or dirty.  Try cleaning it with contact cleaner or just do some "serious" jiggling of the switch to see if it makes contact on ANY band.  I have an R4C that has the same problem from time-to-time.  Usually, mine will go dead on one or two bands, but the others will be OK.  Replacing a bandswitch would not be fun.  Good luck.
Tom, KR4BD
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WB6BYU
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« Reply #5 on: October 15, 2001, 12:36:06 PM »

First, remove as many possible variables from the system as
possible.  Unplug the tuner and coax.  String a wire around the room
(perhaps 20 - 30') and plug it directly into the antenna jack.
Using this antenna, tune across all the ham bands and see if you
can hear any signals on any of them.  (Make sure you peak the
preselector when you change bands.)  If the rig has a crystal
calibrator, see if you can pick up the signals from it on all bands.

Possible problems if you can't hear anything on any band:
- Bad tube in RF or IF stage
- oscillator not working
- bad connection in antenna relay
- strong local noise source masking all signals

Possible problems if you can't hear anything on just some bands:
- band is dead at the moment
- crystal oscillator not working or on wrong frequency
- bad bandswitch connection
- rig not alligned for that band

If you can hear signals on all bands:
- shorted coax
- antenna tuner not adjusted properly

As was mentioned previously, much of the stock Drake gear only
came with crystals for 28.5 - 29.0 MHz or so on 10m, and crystals
for the rest of the band were considered options.  So there may be
positions on the bandswitch which are not activated inside the rig.

Checking the receiver on the other bands will help to pinpoint what
parts of the receiver are working and which are not.
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W7DJM
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« Reply #6 on: October 15, 2001, 01:37:00 PM »

I  think WB6BYU gave you some good tips.   There is, however, no antenna relay in the receiver.   I would ELIMINATE as much cableing as possible.  PULL ALL of the transmitter/receiver interconnect cables out.  Make sure you have a speaker of course, and an antenna.

I don't remember for certain, but seems to me you have to have the mute jack shorted

Make SURE, absolutely sure, that the crystals and switches are in the correct spot.

Last, in addition to the above, have you moved or shipped the rx lately?  I've had trouble with the alignment trimmers along the side of the radio getting bumped out of alignment with a little physical moving of the rx.  Also, you might visually look at the bandswitch,  the crystal switch, and the preselector tuning to make sure they are all moving with the shaft as they should.  I've had trouble with the gear reduction on the preselector shaft, and had one bandswitch break a wafer, so that it was not moving properly with the shaft.

And, the band could be dead!!
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K3UOD
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Posts: 145




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« Reply #7 on: October 15, 2001, 02:29:32 PM »

The mute jack must be shorted if the function switch is in the MUTE, NB, or CAL positions but not in the ON position.  Of course if you want to hear the crystal calibrator (CAL position) you need a shorting plug.

A tube tester is a very handy thing to have for working on vintage rigs.  A pile of tubes also.

But first, I'd check all of the voltages on all of the tube sockets.  Use a high impedance voltmeter.
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K3UOD
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« Reply #8 on: October 15, 2001, 02:35:30 PM »

Another note:  Don't use spray type contact cleaners on the phenolic switches.  It causes the wafers to swell and makes the switch stiff to turn.  Use a brush and wood alcohol instead.
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