[Elecraft] WTB Trimble ThunderBolt for K3EXREF / QS1R

[David Anderson]

Max,

I bought one of the BG7TBL GPSDO  from the same seller on eBay. I actually was just looking for a 10 MHz distribution amplifier and found that he was selling the GPSDO along with matching Distribution amp for a very good price. There were options of a square wave output version or a sine wave output (which is what I purchased). 

The 8 output Distribution amp also contains a Morion 10 MHz double oven oscillator as well, which takes over if the input signal from the GPSDO is disconnected.  

I was not aware the Morion oscillator was doubling the frequency to reach 10 MHz, I have not found any documentation that mentions that anywhere else. The device is marked as 10 MHz.

The included 12 V power supplies work fine, however they are wall warts with I think American 2 pin plugs, which need adapters to fit UK mains sockets. You need a fair amount of current for the ovens when they are heating up, so cannot just substitute a 1 amp supply.

I opened up both units and the construction is very well done. No schematic or block diagram was supplied, though you can read what some of the chips are, in particular the GPS receiver is an NEO-6M. 

They may not satisfy the Time Nuts in every way, but they are good enough for for my uses as a stable 10 MHz for locking other oscillators.

There is also a serial port (at true RS-232 levels so beware if you try to connect it to something like an Arduino unless you build a level shifter). It outputs the usual GPS NMEA sentences.

I do have a another time and frequency standard which is an old HP Z3801A, it is probably better, but for my uses I would not be able to tell the difference. The HP is much larger, requires a 50 Volt supply so not nearly as portable. It also cost a lot more when I bought it on eBay quite a few years ago.


73

David Anderson GM4JJJ 

> On 6 Apr 2015, at 00:44, M. George <m.matthew.george at gmail.com> wrote:
> 
> A follow up to my write up... I should have included more details from
> personal emails I received from Dave, G3TJP.  Bob W7AVK also mentioned the
> BG7TBL GPS Disciplined Clock and I totally got my wires crossed and didn't
> mention G3TJP in my write-up. Sigh....  Apologies to Mr. Lankshear... Dave
> took some time in a personal email to point out the follow about the BG7TBL
> which is going for ~144.00 on ebay... it really is a nice package... here
> are some of Dave's comments (in hindsight, I wonder if this would have been
> the way to go):
> 
> G3TJP: "It’s a very neat and small unit, very professionally produced and
> comes complete with power supply and GPS antenna.  I bought one and then a
> second one as a gift to a good friend.  It uses the Morion double oven
> 10MHz xtal oscillator, or equivalent.  The output is a decent sine wave
> with just enough distortion to give good harmonics at 10MHz intervals up to
> at least 50MHz, which is as far as I’ve checked.  The Morion is actually a
> 5MHz oscillator that’s doubled to 10MHz, so you have a usable, locked
> signal at 5MHz also."
> 
> Dave also mentioned that the seller 'fly-xy' is a decent guy and will ben
> over backwards to help you as you treat him fairly.  i.e. if something
> needs to be returned or corrected.  Plus, this unit is a turnkey package
> and he also sells a 10mhz distribution amplifier that looks interesting...
> another BG7TBL design.
> 
> KE5FX has also reviewed Bob W7AVK's BG7TBL and has a nice comparison write
> up on his website (KE5FX of Lady Heather fame).  The comparison is easy to
> find on KE5FX's site.
> 
> Again, thanks to everyone that had input... I tried to mention everyone
> that pointed me in the right direction off the list and leaving out Dave
> G3TJP was my mistake.
> 
> Regards, Max NG7M
> 
>