[GreenKeys] Range Finder Setting/Distortion usage?

[Jeff G]

DPDT switch could temporarily reverse the meter without having to replace
it.

Jeff

On Mon, Feb 6, 2023 at 6:28 PM W2HX <w2hx at w2hx.com> wrote:

> Ok, never mind. As Nick pointed out, changing the polarity on the external
> loop will make the ASR just run open. So it isn't that. What is frustrating
> here, and the reason I thought about this, I have the panel meter 0-100mA.
> If I plug it into my jackfield, it reads correctly. When I try to plug it
> into the BJ jack (Bias Jack) to read the bias current, it tries to go
> negative. So the polarity of the bias jack is opposite of the jackfield. I
> could put a reversing switch in, or a bridge rectifier. Or replace the
> meter with a 100-0-100 meter. I dunno. I was hoping to get everything to
> the same polarity so that I could use the same meter for adjusting.
>
>
> 73 Eugene W2HX
> Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos
>
>
> -----Original Message-----
> From: W2HX
> Sent: Monday, February 6, 2023 5:50 PM
> To: harold at w6iwi.org; greenkeys at mailman.qth.net
> Subject: RE: [GreenKeys] Range Finder Setting/Distortion usage?
>
> Ok guys. So here is my next question about this. Could there be a
> detrimental affect of the bias supply is not of the same polarity of the
> external supply? I ask because recently I made a new jackfield for my loop.
> And on everyone's suggestion I made the "tip" positive. In the past, I
> don't think it was. So I am wondering if I might be reducing the effect of
> the bias windings on the relay if the main winding from the external loop
> changed polarity?
>
>
> 73 Eugene W2HX
> Subscribe to my Youtube Channel: https://www.youtube.com/@w2hx/videos
>
>
> -----Original Message-----
> From: greenkeys-bounces at mailman.qth.net <greenkeys-bounces at mailman.qth.net>
> On Behalf Of Harold Hallikainen via GreenKeys
> Sent: Sunday, February 5, 2023 9:48 PM
> To: greenkeys at mailman.qth.net
> Subject: Re: [GreenKeys] Range Finder Setting/Distortion usage?
>
>
>
> On Sun, February 5, 2023 7:32 pm, Jim Cooper wrote:
> > On 6 Feb 2023 at 1:56, W2HX wrote:
> >
> >>
> >> I wonder... the ASR (which seems
> >> less accurate than the KSR) has an
> >> internal loop supply and relay to
> >> key the page printer. This relay also has a bias adjustment. I have
> >> that adjustment at 30mA as per some notes from the guy I bought it
> >> from. Could this bias current in the ASR play a part in these two
> >> machines behaving slightly differently? If so, then I can play around
> >> with adjusting the bias current on the ASR (I guess I could play with
> >> it regardless, but thought I'd get the skinny from the experts who
> >> know.
> >
> > That could definitely explain the 'skew' to the higher numbers ...
> > imo
> >
> > w2jc
> >
>
> I agree. I've always wondered why a polar relay is used if a polar line is
> not being used. It seems to add more complexity and more things to go
> wrong. MAYBE the polar relay and internal loop supply can be bypassed and
> just have the loop and terminal unit drive the selector magnets directly.
> Failing that, I'd try to adjust the polar relay such that there is no bias
> coming out of it. If possible to sample the loop current after the polar
> relay, then adjust the polar relay so both mark and space on RY are 22 ms
> long. Ideally a test signal would be available with a 22 ms stop bit
> instead of the usual 31 ms. That makes it easier to see on a scope since
> every bit is the same length. Also, if all alternating bits are the same
> length, the average current on a slow moving meter would be 30 mA.
> However, since there are 5 data bits, start is space, and stop is mark,
> even with a 22 ms stop bit, getting a 50% duty cycle with an R or Y is not
> possible. I did create some audio with random 22 ms bits at
> https://w6iwi.org/rtty/audio/ for DSP TU testing (generating the eye
> diagrams at https://w6iwi.org/rtty/DspTU/ .
>
> In general, I think the ideal design has zero parts, and a polar relay
> that is not converting a polar circuit to a neutral circuit is not heading
> us towards the ideal design.
>
> Good luck!
>
> Harold
> https://w6iwi.org
>
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