GPSDO With 7000 DLE

W2SDR
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Joined: Sat Apr 15, 2017 11:36 am

GPSDO With 7000 DLE

Postby W2SDR » Fri Aug 31, 2018 10:14 pm

BG7 TBL is the unit I am using. When connected to my 200D no calibration was needed in the menu. Now with the 7000 I have to adjust the calibration to get it aligned with WWV. Is this normal?
Bryan W4WMT
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Joined: Sun Apr 09, 2017 10:12 pm

Re: GPSDO With 7000 DLE

Postby Bryan W4WMT » Sat Sep 01, 2018 1:41 am

No, it should lock in immediately with no calibration needed.
W2FMU had some initial trouble with his 7000 locking to a 10MHz GPSDO, but now I can’t remember what the fix was. Get in touch with Ernie for more/better info.

73
W2SDR
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Re: GPSDO With 7000 DLE

Postby W2SDR » Sat Sep 01, 2018 8:27 am

Bryan,
It locks in no problem, but I have to adjust the "correction factor" in the menu to get it on freq with WWV. I ended up with a setting of
1.00000850. It stays right there once adjusted however.
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w-u-2-o
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Re: GPSDO With 7000 DLE

Postby w-u-2-o » Sat Sep 01, 2018 12:53 pm

It may be locking, or it may not be. In either case, it is definitely NOT correct. That is an 85Hz error, which is huge, and indicative of a free running Orion MKII board regardless of its stability.

I'd suggest a few things:

1. Make sure it is still locking up your other radio correctly.
2. The output of most BG7TBL units is about +13dBm into a 50 Ohm load. Put 10 or 20dB of attenuation on the output of the unit and, using one of your radios, tune in the 10MHz output and measure its power level. It may be that you have a unit that has a lower power output level that just barely works on one radio and doesn't work on the other. Things seem to stop working around here for me around +6 or +7dBm. You can also use a spectrum analyzer instead of your radio if you have one, of course.
3. Refer to the schematic in the stickied GPSDO topic here. Check and/or play with the positions of two jumpers. Normally I would expect that you'd want them both in place so that you had a 50 Ohm termination and an unbalanced input, but you know what they say: if it's stupid and it works it's not stupid. So if you find a combination that works properly stick with it :)

73,

Scott
W2SDR
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Re: GPSDO With 7000 DLE

Postby W2SDR » Sat Sep 01, 2018 2:03 pm

Scott,
My BG7TBL is only putting out -5 dbm into the radio thru 10db att. In other words +5 dbm
Frank
W2SDR
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Re: GPSDO With 7000 DLE

Postby W2SDR » Sat Sep 01, 2018 2:22 pm

How difficult is it to get to these jumpers?
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w-u-2-o
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Re: GPSDO With 7000 DLE

Postby w-u-2-o » Sat Sep 01, 2018 3:08 pm

My guess is that the +5dBm output is marginal and will work for some radios but not others, depending on component tolerances. I know that Abhi has said that it should work at 0dBm, but that has not been my experience.

I've never taken apart a 7000 as I don't have one to take apart. If it is anything like the 200D, drop the front panel (screws) and rear panel (screws and nuts on BNCs), remove the screws from the bottom plate, and slide the bottom panel around a little (be careful of the wiring, of course) to visualize the jumpers. Unfortunately, I do not have a photo of the Orion MKII to see where those jumpers are.
W2SDR
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Re: GPSDO With 7000 DLE

Postby W2SDR » Sat Sep 01, 2018 4:43 pm

Thanks Scott, I’ll think about all my options. I’m leaning on sticking with the quite stable built in TCXO!!

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