[time-nuts] TrueTime AL-AK GPS receiver help

Bob Camp kb8tq at n1k.org
Thu Apr 30 17:58:19 EDT 2015


I guess the first question would be:

Are we sure it’s an AL-AK and not an XL-AK? 

Past that it becomes a fairly involved process of, is it worth real money to get this up and running? 

If we are talking about a $20 eBay find that is worth another $5 to have somebody else get it running, the 
conversation is a real short one. 

If the AL-AK has some inherent value (it’s a working GPS disciplined Cs  maybe) then putting a few hundred
dollars into checking it out and getting it running might make sense. If it’s like most of the parts from that 
era, the delta between getting it checked and getting it running is pretty small. 

Once you *do* have it running, what do you have?

1) Leap second problems
2) GPS year rollover problems
3) Tracking issues
4) A noisy receiver with very few correlators
5) Software support issues

This is an unusual box that is at least 20 years old. It *will* have at least some of the listed issues and 
may have all of them. Fixing them will be impossible. 


Why bring up all of the negatives? I for one have been sucked into this kind of thing a *lot* of times
in the past. Just a few more this or that and it’ll be running fine. Much better to figure out the likely
cost and outcome first. That’s *very* hard to do, and even harder to follow through on. If you can’t 
do the work yourself, the cost isn’t just lost time. This can cost real cash. 


> On Apr 30, 2015, at 12:50 PM, Tom Van Baak <tvb at LeapSecond.com> wrote:
> I received this email. Anyone have a good answer?
> Thanks,
> /tvb
> ----------
> Someone on ebay advised me to contact your website in hopes that someone in your organization can help me with my TrueTime model AL-AK GPS Receiver. I need to send it to someone so that they can check it to see if it works and can track Satellites.  This receiver has the onboard up/down convertor board that changes the receiver input frequency which is set at 4.092 MHz. I don't have the needed down converter at the antenna. I bought this receiver on ebay from someone who told me that he doesn't have the down converter as well and can't figure out how to get it to work at 1575.42 MHz. He also didn't know if this receiver can be setup for a 1575.42 MHz by removing the onboard converter and changing some DIP switches. If one of your members can at least check out the receiver at 4.092 MHz for satellite tracking That would be a big help ...
> ----------
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