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 Post subject: Heathkit DX Grid Voltages
PostPosted: Jan Sun 08, 2017 12:23 am 
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Joined: May Sun 08, 2011 12:17 am
Posts: 9
Location: Connecticut
I have a DX 60 transmitter. the driver grid voltage is -14 volts it should be -95 volts. The osc grid voltage is at -27.8 volts and should be -18 volts. Both in key down.

Any ideas where to look. I am thinking of an open or shorted capacitor.

Thanks for any help.
73,
Mike


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 Post subject: Re: Heathkit DX Grid Voltages
PostPosted: Jan Sun 08, 2017 2:43 am 
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Joined: Jan Fri 06, 2012 8:47 pm
Posts: 5692
n1chp wrote:
I have a DX 60 transmitter. the driver grid voltage is -14 volts it should be -95 volts. The osc grid voltage is at -27.8 volts and should be -18 volts. Both in key down.
In "key down" mode a lot of the negative bias voltage is shorted to ground by the key closure to ground. The negative voltage at the oscillator under key down conditions is a function of the operation of the oscillator as an oscillator and it will vary from crystal to crystal. Of course without a crystal or VFO input the transmitter will not transmit.

The bias voltage at the driver should NOT be -95 V under "key down" conditions or else the driver would be "turned OFF" and the transmitter would not transmit.

I don't have a copy of the documentation handy to determine specifically what the voltages should be under key down conditions.

Curtis Eickerman

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 Post subject: Re: Heathkit DX Grid Voltages
PostPosted: Jan Sun 08, 2017 2:43 pm 
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Joined: May Sun 08, 2011 12:17 am
Posts: 9
Location: Connecticut
Hi Curtis, Thank for getting back to me.The DX 60 specs call for those voltages in the troubleshooting section of the manual.

My plan is to look at all of the other voltages and see that they are all good. Going to check section by section. I did find a loose wire and soldered it. Tubes are good as well. At least there is not any smoke. When I do key down I do get a reading on the plate of 3ma so something is working. Just no output.

I'll continue to look for bad components.

Thanks again.
73,
Mike


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 Post subject: Re: Heathkit DX Grid Voltages
PostPosted: Jan Sun 08, 2017 3:33 pm 
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Joined: May Sat 12, 2012 1:33 pm
Posts: 1179
Location: Rochester, NY.
I had a DX-60B for many years. Schematic (with expected socket voltages) here:
http://www.nostalgickitscentral.com/hea ... _dx60b.pdf
Have you tried swapping the 6CL6 tubes and re-reading voltages?
As stated (and noted on the schematic), crystal activity will play a part in voltage readings.
Follow the 'Notes' section to get the expected voltage readings shown on the schematic. As you say, there may be other voltages that are off. Finding them may help with diagnosis.


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 Post subject: Re: Heathkit DX Grid Voltages
PostPosted: Jan Sun 08, 2017 4:41 pm 
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Joined: May Sun 08, 2011 12:17 am
Posts: 9
Location: Connecticut
Thank you for the additional suggestions and the link. I'll be working on it.


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 Post subject: Re: Heathkit DX Grid Voltages
PostPosted: Jan Sun 08, 2017 6:18 pm 
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Joined: May Fri 01, 2015 2:33 am
Posts: 755
Location: Roslyn,Pa 19001
Don't know what you are using for a meter but I've found that sometimes digital meters can get confused with voltages w/rf mixed in with them. Better to stick w/the old '260 than a modern job. Many years ago I was working on a tube type TV trying to get the horizontal osc straightened out and w/the Beckman 310 (digital meter) the measurement where way out of line and didn't make any sense. My old Triplett 630 told the story.

GL
Terry N3GTE


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 Post subject: Re: Heathkit DX Grid Voltages
PostPosted: Jan Sun 08, 2017 11:02 pm 
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Joined: May Sun 08, 2011 12:17 am
Posts: 9
Location: Connecticut
Terry, Good point. I have two old meters I will try. Should use them. Maybe a loading problem.
Thanks and 73,
Mike
N1CHP


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 Post subject: Re: Heathkit DX Grid Voltages
PostPosted: Jan Mon 09, 2017 1:46 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 485
Location: Pasadena CA USA
Did it ever work? All or most of these were built as a kit and there may be wiring errors that prevented this thing from ever working. You found one wiring problem there may be others.


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 Post subject: Re: Heathkit DX Grid Voltages
PostPosted: Jan Tue 10, 2017 2:35 am 
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Joined: May Sun 08, 2011 12:17 am
Posts: 9
Location: Connecticut
I bought the DX 60 at a Hamfest. I did not expect it to work. The mic button connector was missing and so was the modulator circuit. I di have it making a tone in a receiver but then the 6146 shorted. So I'll be looking for things in that path that me be a problem.


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