Posted by
Douglas Westover on
Nov 18, 2004; 7:53pm
URL: http://elecraft.85.s1.nabble.com/Low-voltage-on-AGC-threshold-tp371652p371658.html
Don't confuse precision with accuracy. Why not measure some
fresh 1.5 volt batteries (which should actually measure around
1.6 volts), that should give you a quick check of your meter's
accuracy.
73,
Doug
W6JD
----- Original Message -----
From: "Mike, W8ENG" <
[hidden email]>
To: <
[hidden email]>
Cc: <
[hidden email]>
Sent: Wednesday, November 17, 2004 4:15 PM
Subject: Re: [Elecraft] Low voltage on AGC threshold
> 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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