[vna] Signal Generator phase meter off by 180 degrees?

[mchase5000 at bellsouth.net]

So. Have there been any calibration improvements or developments since I 
spent my $700?  Even with a new one, mine still looks prety wavey / choppy 
(if you recall all those pictures I sent you several months back, and all 
the Terrible customer "service" I had with TenTec...)

There must be something that is still not right with what I have.

Thanks again
Mark Chase


----- Original Message ----- 
From: <tom.mcdermott4 at sbcglobal.net>
To: "'TAPR/Ten-Tec VNA Users List'" <vna at lists.tapr.org>
Sent: Tuesday, August 01, 2006 11:49 PM
Subject: RE: [vna] Signal Generator phase meter off by 180 degrees?


>
> Sorry, the VNA and development system have been boxed up
> for 3 months while I sold the house and moved. Got it
> unboxed and hooked up tonight, so should be able to get
> started again.
>
> Yes - the phase meter on the signal generator is off by 180
> degrees. I'll add that the to fix list for it.
>
> -- Tom, N5EG
>
>
>
>
>
>> -----Original Message-----
>> From: vna-bounces at lists.tapr.org
>> [mailto:vna-bounces at lists.tapr.org] On Behalf Of Ed Nisley
>> Sent: Friday, July 21, 2006 1:11 PM
>> To: vna at lists.tapr.org
>> Subject: [vna] Signal Generator phase meter off by 180 degrees?
>>
>>
>> While I was figuring out S2P files, I used the Signal
>> Generator to get a fixed output for 'scope probing.
>>
>> The needle seems to be 180 degrees off...
>>
>> 1) Where the VNA plot shows 0 degrees at the center of my
>> filter's passband, the SG needle is pinned to either side
>> and flops back & forth with small variations.
>>
>> 2) On the low side of the passband where the VNA shows +
>> phase the SG shows negative; as the VNA approaches +180,
>> the SG approaches 0 from the negative side.
>>
>> 3) On the high side where the VNA shows - phase, the SG
>> shows positive; as the VNA approaches -180 the SG
>> approaches 0 from the positive side.
>>
>> I also tried this with a plain old resistor: the SG's meter
>> is pinned hard left, showing -180 degrees, at all
>> frequencies. The VNA plot shows 0 degrees, as you'd expect.
>>
>> The source in AnalogMeterControl.h is pretty straightforward
>> and looks like it can't possibly go wrong. It says the
>> meter scale is 180 = hard left, 0 = center, +180 = hard
>> right, as I expected. That means MeterValue emerges from
>> the underlying VNA hardware interface incorrectly, which is
>> well beyond me to figure out...
>>
>> This is using SG Version 1.1, but I can't find that source
>> code file.
>>
>> Am I standing on my head yet again?
>>
>> Thanks...
>>
>> -- 
>> Ed
>>
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>>
>
>
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