[TowerTalk] HD-73

[Larry Stowell]

Dan
They are shown in my  schematic as 1N5401 3amp 100v

73 Larry K1ZW

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Message: 4
Date: Mon, 23 Sep 2013 11:43:18 -0700
From: "Richard (Rick) Karlquist" <richard at karlquist.com>
To: Dan Evans <k9zf at yahoo.com>
Cc: "towertalk at contesting.com" <towertalk at contesting.com>
Subject: Re: [TowerTalk] HD-73 Rotator issues--digital readout
Message-ID: <52408BC6.8080709 at karlquist.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed

On 9/23/2013 5:58 AM, Dan Evans wrote:
>
> More trouble shooting found two bad diodes where the pot leads come into 
> the controller.  I found a couple of 1N914's in the junk box and swapped 
> these out.   Now the meter works, but is horribly inaccurate.
>
> Yesterday I got a couple more hours to dig into it.  I put the circuit 
> board under the magnifier so I could see it (my vision ain't what it used 
> to be...) and spotted a resistor that had been pretty hot.   I swapped out 
> this 15 ohm resistor and varified all of the other resistors and diodes 
> checked OK.   Success at last!  It now appears to be working normally.
>
> So, if you have a similar problem with your controller, check the diodes 
> on the pot leads and go over all of the resistors on the circuit board.
>
> And now that I know the workings of this rotator so well, I'm thinking of 
> some mods.  I would love to have a digital display...
>
> 73
> Dan

AFAIK, there are no diodes across the pot leads; what in the world could
they possibly do?  At least they are not shown on any version of the
schematic I have seen.  I think what we have here is some poor clown
who got a bunch of RF on his control lines and was attempting to fix

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End of TowerTalk Digest, Vol 129, Issue 47
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