[Elecraft] K3s BG7TBL 10 MHz reference with K3EXREF

[Gary Smith]

Today was a pleasant surprise, the BG7TBL GPS Disciplined Oscillator, 
external reference arrived and much faster than I expected China Post 
to provide. There is no software or tech manual that comes with it so 
I didn't know what to expect. There are 3 LEDs an ALM, GPS Lock & 
Run. No idea what to expect with these & a web search did not lead me 
to a manual. 

This one is listed with the 2015-09-17 date (Version) stamped on the 
front. Ebay # 331800738725 - It contained the GPSDO, antenna and 12V 
wall wart. The GPS is a U-blox NEO-6M-0-001 and the OXCO is a 
Oscilloquartz 8663-XS dual oven. Reading the stats on the stability, 
it's pretty amazing, search down for the 8663:

http://tinyurl.com/h4j58ea

There's some interesting and lengthy discussion about this series of 
GPSDO on the eevblog site. Interestingly, the OXCO in this version of 
the unit is different than listed on the master reference on the 
first page:

http://www.eevblog.com/forum/testgear/bg7tbl-gpsdo-master-reference/

I did find the ALM LED remained on for 20 minutes or so and with a 
GPS lock (maybe one minute) the LED came on and remains on. The Run 
LED flashes around 3 times/second. Not sure what the flashing 
represents.

I attached it to the K3EXREF and followed the directions to enable it 
in REF-CAL, in configuration. The effect wasn't immediately obvious 
but when I went to copy RTTY there was an apparent improvement to the 
copy in MMTTY and after transmitting, it seems like the recovery to 
copy is much faster than before. I'm looking forward to trying some 
of the digital modes and am happy this reference is engaged and the 
stability will be kept to the minimum needed.

One thing I am wondering is how often the K3s utilizes the 10 KHz 
info being provided. I think I read every 4 seconds or so but I'm not 
sure I have that right. Nifty little piece of equipment to work with 
the K3/K3s

Hope some find this info useful.

73,

Gary
KA1J