[time-nuts] Recommendations for a newbie?

[Bob Camp]

Hi

Ok, I've got at least one of all of these sitting in the basement. They are a very much mixed bag. Some of the HP's are quite good. Others not so much. The variation isn't so much model to model. They vary unit to unit. The TBolt's vary by year. Roughly they group as pre-2001, 2001 to 2003, and post 2004. The HP's also seem to die a bit quicker than the TBolts.  I'd *guess* the failure rate is at least 3X.

On a good unit, the HP Smart Clock software does a better job than the TBolt stock software. On a unit with "issues" the software chugs (switches settings) a lot. A manually tuned TBolt in a good environment can do very well. In a poor environment it's going go look like a boosted single oven 3801, but not be as good as the true double oven (MTI OCXO) version of the 3805. 

The strange temperature chip in the later TBolts isn't much of an issue. The chip is poorly located for temperature control. It only seems to impact the plots on Lady Heather. Trimble wasn't bothered enough by it to patch the firmware.

Bottom line, If the price is identical for all of them, go with the HP's. If the TBolt's are half (or 1/4) the delivered price of the HP's go with the TBolt. Either way, plan on getting a couple of them.   

Bob

On Sep 8, 2012, at 8:11 AM, Azelio Boriani <azelio.boriani at screen.it> wrote:

> Can't compare the Z3805A to the HP58503A but I have found in the archives
> that the Z3805A has a 16 channel GPS receiver and it is better to find the
> Symmetricom labeled one as it has a real double-oven OCXO. According to a
> 2010 time-nut message the Z3805A is almost the same as the TBolt.
> 
> On Sat, Sep 8, 2012 at 3:53 AM, Edgardo Molina <xe1xus at amsat.org> wrote:
> 
>> Dear Said,
>> 
>> Thank you for your kind explanation. I will be considering such a purchase
>> in the near future. I will keep you informed about my experiences. You have
>> a nice evening.
>> 
>> Regards,
>> 
>> 
>> 
>> Edgardo Molina
>> Dirección IPTEL
>> 
>> www.iptel.net.mx
>> 
>> T : 55 55 55202444
>> M : 04455 20501854
>> 
>> Piensa en Bits SA de CV
>> 
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>> 
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>> On Sep 7, 2012, at 8:14 PM, SAIDJACK at aol.com wrote:
>> 
>>> Hi Edgardo,
>>> 
>>> they work well for me, look brand-new, and came with power supply, rs-232
>>> cable, and antenna. I think it's a 5V antenna. The unit had about 37000
>> on
>>> the lifetime.
>>> 
>>> The seller has close up photos, that's what the units look like. I
>> plugged
>>> in the power, ran GPSCon to start an Auto-Survey, and they just worked.
>>> 
>>> I now get less than 3us predicted drift over 24 hours from one of the
>>> units, which is quite good according to others.
>>> 
>>> I think these are pretty good for the money (free shipping on mine) but
>>> there are differences between the three units I have just like the Z3801A
>>> plots  on leapsecond.com.
>>> 
>>> Hope that helps,
>>> Said
>>> 
>>> 
>>> In a message dated 9/7/2012 17:13:22 Pacific Daylight Time,
>>> xe1xus at amsat.org writes:
>>> 
>>> Dear  Said,
>>> 
>>> Good afternoon. How is the service and cosmetic condition of the  HP GPS
>>> products you have bought from this source? I am considering a Z3805A
>> just for
>>> the sake of owning one and the versatility of plug and play.   Still
>> afraid
>>> to take the plunge.
>>> 
>>> Did you buy a raw unit? Or as a kit  with antenna. Is that a 5V or 12V
>>> antenna?  I am integrating a TBolt into  a 1U rack case which also has
>> space for
>>> a Rb oscillator for future  disciplining. Got a nice TBolt monitor and
>>> would love to also include a  frequency divider to get 5 and 1MHz from
>> the
>>> TBolt.
>>> 
>>> Your kind comments  are welcome. Thank you.
>>> 
>>> Regards,
>>> 
>>> 
>>> 
>>> Edgardo  Molina
>>> Dirección IPTEL
>>> 
>>> 
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