[time-nuts] EIP545A 18GHz counter query

[paul swed]

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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