Posted by
Mike, W8ENG on
Nov 18, 2004; 12:15am
URL: http://elecraft.85.s1.nabble.com/Low-voltage-on-AGC-threshold-tp371652p371657.html
John, My DMM is a $30 Radio Shack unit. I do not have anything handy to
calibrate or check the accuracy. It does report DC voiltage to 2 decimal
points, but I doubt that it is that accurate. Any way, for now I'm
proceeding with construction.
Mike, W8ENG
----- Original Message -----
From: "John R. Lonigro" <
[hidden email]>
To: "Mike, W8ENG" <
[hidden email]>
Cc: <
[hidden email]>
Sent: Tuesday, November 16, 2004 10:29 PM
Subject: Re: [Elecraft] Low voltage on AGC threshold
> Mike:
>
> How accurate is your DMM? The 8v and 5v regulators should still produce
> 8 and 5 volts even with a slightly low supply voltage. Also, if the
> K2's internal voltmeter reads the same as your DMM, that tells me your
> DMM is reading low because there is a diode in the K2 power line which
> will make the K2 internal voltmeter read LESS than an accurate external
> DMM. Only if the external DMM reads low would the two voltmeters agree.
>
> Try to check your voltages with a different DMM. My guess is your
> problem is NOT low voltage all around. Good luck.
>
> 73's
>
> John AA0VE
>
> Mike, W8ENG wrote:
>
> >This is an update to my earlier post. I touched up a solder joint and
> >reassembled the radio. The voltage on pin 5 of U2 was still 3.78 volts,
> >with the RF gain set fully clockwise. The input voltage from my power
> >supply was 12.4 volts, both on my DMM and on the K2's internal voltmeter.
> >The voltage out on the 8v regulator was 7.8,a nd on the 5v regulator was
> >4.9.
> >
> >I'm thinking that the problem may be low voltage all around. I don't
have a
> >better power supply to check with at a higher voltage.
> >
> >Any addational help or comments would be appreciated.
> >
> >73, Mike, W8ENG
> >
> >
>
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