[time-nuts] What's best an HP 58503A, Z3805A, or Z3801A upgraded to 58503A?

[Bob Camp]

Hi

I have several of all of the below except for the “lab versions”. They are a mixed bag as you get them. Some are in very good shape. Others have obvious signs of water exposure. Some have minor to major physical damage. Some of them run for years. Some die in the first year.

> On Nov 30, 2014, at 9:03 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <drkirkby at kirkbymicrowave.co.uk> wrote:
> 
> I'm seriously giving consideration to getting an HP frequency
> standard, and are looking at some from the Chinese seller "yixunhk" on
> eBay. I would be interested in the views of people on the merits of
> these 5 quite similar items as a GPS locked frequency standard. I'm
> not really so bothered about performance as a time-standard. Most
> around $500 with carriage, although the one with the inbuilt power
> supply is quite a bit more.
> 
> I suspect they are all good enough for a frequency standard, but if X
> is better than Y, and cost the same or very similar, I would rather
> get X.
> 
> 1) Z3805A http://www.ebay.com/itm/251527236609
> * 16 channels
> * double oven
> * dual outputs
> * $499 + free carriage
> 
> 2) Z3805A http://www.ebay.com/itm/271324714268
> 
> * 8-Channels GPS Receive
> * 6-Channel GPS Parallel tracking
> * double oven
> * dual outputs.
> * $399+ carriage, so probably the same cost as #1 above
> 
> Why do #1 and #2 have the same part numbers, but a different number of
> channels??? One has 16, the other 6/8.

There are multiple versions of the 3805. There are two GPS modules in them and two OCXO’s. You mostly see them in pairs (260 OCXO with Furuno GPS / 10811 with Motorola GPS).

> 
> 3) Z3801A upgraded to 58503A http://www.ebay.com/itm/271482477428
> 
> * 6-channel, Parallel tracking
> * Single oven
> * Single output
> * $499 with free carriage

One would *hope* that this is a well cared for 3801. Some of them did not get treated well in the savage process. 

> 
> 4) Z3805A upgraded to 58503A http://www.ebay.com/itm/281294190956
> * 6-channel, Parallel tracking
> * Double oven
> * Dual outputs
> * $550 with free carriage, so a little more expensive than the others.

Exactly the same comment as above on the 3801. Paying extra and getting a junker would not make me very happy. 

> 
> 5) 58503A http://www.ebay.com/itm/271642102264
> 
> * 6-channel, Parallel tracking
> * C/A code, L1 carrier
> * Single oven
> * Single outputs
> * $799 + free carriage, which is significantly more expensive than the
> others, but does have the advantage of built in power supply, which I
> must admit I do find attractive, but at $300 more, it is quite a jump
> in price.
> 

As far as I can see, there are really only two basic sets of hardware here.

1) The earlier 10811 / Motorola design 

2) The later 260 / Furuno design. 

The rest is packaging and luck. ADEV performance wise, some of the 3801’s do quite well, some not quite as well. There was a lot of variation in the 10811 since it was not targeted at ADEV. Phase noise wise, the 10811 design will be better. Both will have spurs. The 10811 designs are older and may have more running hours on them. Either one may have been impacted negatively by the salvage process. 

Bob 

> Dave
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