[time-nuts] EIP545A 18GHz counter query

Chris Wilson chris at chriswilson.tv
Sun Dec 9 19:53:54 UTC 2012



> Chris
> TP4 is not all that helpful its a control signal.
> So let me back up for a minute. What are we troubleshooting?
> I was thinking band 2 was semi working and you still had a totally dead
> band 3.
> My comments have been around trying to see what was going on with 3.
> Other comment.
> I think we should take this offline. Most likely driving time-nuts nuts. :-)
> Do you use skype?
> Regards
> Paul

> On Sun, Dec 9, 2012 at 11:29 AM, paul swed <paulswedb at gmail.com> wrote:

>> Didier is 100% correct though I use a 10 db pad for exactly the same
>> purpose. You have to be careful. In your case there is a +28 db power amp
>> that feeds the yig mixer in the 545. That would destroy the spectrum
>> analyzer frontend. In fact if measuring that component you would want 30 db
>> of loss using a 2 watt pad. Most spectrum analyzers run in the 0 to +5 or
>> so db range.
>>
>> All of that said I actually have to look at your other comments to make
>> some sense of what you are seeing.
>> Regards
>> Paul
>> WB8TSL
>>
>>
>> On Sun, Dec 9, 2012 at 7:22 AM, <shalimr9 at gmail.com> wrote:
>>
>>> Good practice with a spectrum analyzer is to put a 20 dB pad at the input
>>> all the time unless you are sure you don't need it for a particular
>>> measurement.
>>>
>>> It has saved my bacon many times.
>>>
>>> It also protects the input connector from excessive wear.
>>>
>>> Didier KO4BB
>>>
>>>
>>> Sent from my Droid Razr 4G LTE wireless tracker.
>>>
>>>
>>>
>>> -----Original Message-----
>>> From: Chris Wilson <chris at chriswilson.tv>
>>> To: Chris Wilson <chris at chriswilson.tv>, Discussion of precise time and
>>>  frequency measurement <time-nuts at febo.com>
>>> Sent: Sun, 09 Dec 2012 5:54 AM
>>> Subject: Re: [time-nuts] EIP545A 18GHz counter query
>>>
>>>
>>>
>>> > Did do some more reading and I think what I suggest is the right
>>> approach.
>>> > Band 2 and 3 use the same VCO. So if band 2 is generally working
>>> > then its possibly the rf multiplier yig filter mixer diodes etc. But
>>> > if the RF detectors show RF then its going to be a much more
>>> interesting issue.
>>> > I do not know what sort of test equipment you might have. I have
>>> > spectrum analyzers and such. And do agree without extenders that I
>>> don't have its a royal pain.
>>> > Regards
>>> > Paul.
>>>
>>>
>>> 09/12/2012 11:45
>>>
>>> Thanks very much for your input with this, much appreciated. I do have
>>> a spectrum analyser, but it's a bit like having a set of surgeons
>>> implements. Interesting to have, but needing the requisite skill to
>>> use safely :) I can do only the most basic stuff, to be frank I am
>>> very wary of blowing the input stage up by doing something daft!
>>>
>>> I think I follow your train of thought here Paul. But, before seeing
>>> your post I did some tests at TP4, to see if the unit was constantly
>>> scanning for a signal when on Band 2. here is what I found and saw:
>>>
>>> I have now refitted the new Q12, and removed the test 1k resistor.
>>>
>>> OK, the trace from TP4 does different things depending what band it is
>>> on. Bands 1 and 3 it just sits there, #1. On Band 2 it gives what appears
>>> to be two traces, #2. Changing the timebase gives the other trace I show
>>> linked, #3. On bands 1 and 3 only a single trace appears. So Band 2 is
>>> doing something different at TP4, with no input signal. Warm Q12 with
>>> an input signal to Band 2 and the two traces change to a single trace,
>>> #4.
>>>
>>> Once it cools again the two traces return.
>>>
>>> Traces:
>>>
>>> #1  http://www.gatesgarth.com/scope/TP4-band1.jpg
>>>
>>> #2  http://www.gatesgarth.com/scope/TP4-band2.jpg
>>>
>>> #3  http://www.gatesgarth.com/scope/TP4-...t-timebase.jpg
>>>
>>> #4  http://www.gatesgarth.com/scope/TP4-...put-signal.jpg
>>>
>>> I would need explicit instruction to poke about using the SA. It's an
>>> HP 8568B. Thanks again Paul :)
>>>
>>>
>>>
>>> --
>>>        Best Regards,
>>>                    Chris Wilson.
>>>
>>>
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>>
>>
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09/12/2012 19:53

Will send direct e-mail thanks for everyone's he;p and patience.

-- 
       Best Regards,
                   Chris Wilson.




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