[time-nuts] Austron 2201, Tbolt, HP 3801 comparison question

[paul swed]

A lot of great comments.
Hope I do not drop any responses.
I am sure its older also it was $135 and picked it up recently.
Have to say for the $ its actually quite fine and I am happy.

I have had the 3801 at least 10 years now. Picked it up early on and did
some of the original tinkering and reverse engineering. So perhaps is does
have the better oven.
I m looking at what the 38xx software program says its doing at the numbers
match the 2201 very nicely. So beginning to believe that what the 2201 says
may be pretty accurate..

Tom asked if someone was going to make down converters. I might believe
that I was involved in those threads. But it would have been attempt to
make. Not produce.
I have produced 2 main approaches with a number of other sub approaches.
They do not emulate the RF down converter but are dependent on older less
integrated receivers. The key is being able to get to the signals.

First version
Used the odetics antenna and then up converting the 35.42 to 75.42 Mhz.
Easy to say harder to implement then imagined. plus building a 10 Mhz to 40
Mhz multiplier.
though this all worked for a year I don't think many could reproduce it.

Second most recent approach thats really working very well.
A novatel starview 2 receiever provided by another Time-nut. The G2015
chips quite a jewel. Its made by zarlink now for $7.50. Any how it produces
a 40 Mhz clock and has nice filtering and such for the 35 Mhz. Mix them and
you are in business. Though I had been using active mixers with mixed
results. (Pun) I went brute force a week or so ago using a minicircuits
SRA1 type mixer. Boy does that work nicely in fact every things rock solid.
No muss no fuss. Thats the right kind of design.
The hardest part of this effor is attaching the IF wire and 2 wires for the
pecl 40 Mhz clock. Right about at my limits for soldering.

So I do believe the 2201s are really quite a good receiver. There are
numbers of tricks to actually getting them going. But after all the work I
do believe worth it. I have made an offer for a second antenna-less unit.
Considering my first was $5 I am offering more then that. But not going
crazy either such as the silly prices I see on e... for a faulted unit.

Hope every things covered and thanks.
regards
Paul
WB8TSL




On Fri, Apr 6, 2012 at 5:43 PM, Ed Palmer <ed_palmer at sasktel.net> wrote:

> Hi Paul,
>
> I'm sure you've followed the discussions in the past on Tbolt performance
> tuning.  Have you jumped through all the appropriate hoops?  Things like
> precision survey, autotune the oscillator parameters, good antenna
> visibility, mask angle, etc. come to mind.  Having said that, I've found
> that my Z3801A performs somewhat better than my Tbolt.  For example, the 1
> PPS out of my Tbolt has a Standard Deviation of ~ 550 ps and a max-min
> range of ~ 4 ns.  My Z3801A is ~200ps and ~2 ns. so call it twice as good.
>
> FYI, my best GPSDO is a Z3817A with a Standard Deviation of < 100 ps and a
> max-min range of < 1 ns.  That one has an E1938 oscillator.
>
> Ed
>
>
>
> On 4/6/2012 2:24 PM, paul swed wrote:
>
>> Recently I put a 2201 back into service with  a home brew down converter.
>> I am a bit surprised that when I use it to measure the Tbolt and then the
>> HP 3801.
>> The 3801 comes out always better by a decade actually. Granted what I am
>> seeing is way down below a e-12th and in fact what I am reading seems nuts
>> to me.
>> But can a 3801 run that much better then the Tbolt?
>> I kind of thought they would both be in the same region.
>> Thanks
>> Regards
>> Paul
>> WB8TSL
>>
>
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