[time-nuts] problem with Efratom FRS-C from eBay

Bob Q quenbob5 at pacbell.net
Mon Oct 20 04:01:06 UTC 2008

Just a note on my experience with "Rubidium and GPSDO...".  I bought an OCXO 
from him.  I had to set the control voltage to about 70 mV to get 10 MHz 
out, too close to 0V to work in my GPS DO circuit.  The OCXO did not have a 
mechanical adjustment in addition to the electircal adjustment, useful to 
center the range of the electrical adjustment.   I sent an email to the 
seller and he offered to either refund my money or send a replacement unit 
for the cost of postage, without returning the first unit.  The replacement 
unit works fine.
Bob Q.

----- Original Message ----- 
From: "Robert Darlington" <rdarlington at gmail.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Friday, October 17, 2008 8:40 PM
Subject: Re: [time-nuts] problem with Efratom FRS-C from eBay

>I got it, it's working (and it always was).   Reading the manual I see that
> the lock signal can either be high or low depending on how some jumpers 
> are
> set on the servo board.  I unplugged the supply, disconnected the 
> connector,
> and added proper lines to my meter while the unit cooled off a bit and
> rested.  A few minutes later with everything connected I plugged it in.  5
> volts out of the lock line was present while the system hunted.  A couple 
> of
> minutes later and the frequency counter stabilized and the meter went to
> 0.02 volts.   The voltage on the lamp monitor is reading 8.78 to 8.79
> volts.  Stabilized is relative, and if this thing had more digits, I'd 
> like
> to think that I'd have a few more not moving.
> Thanks for helping out guys.  I really appreciate it.
> On Fri, Oct 17, 2008 at 4:47 PM, Robert Darlington 
> <rdarlington at gmail.com>wrote:
>> Hello all,
>> My FRS-C showed up today.  I carefully wired it up and powered it on.  I
>> got a nearly 10MHz signal out.  The frequency counter is dancing around a
>> bit and I get a 0.02 V on the lock indicator line after about an hour 
>> warm
>> up.  Specs show this should happen in under 10 minutes and it looks like 
>> it
>> is not locking.   Dead unit?
>> I obtained it from this ad:
>> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=290262243079
>> The unit that I received does not show TTL after the frequency and the
>> scope output looks like a cross between a sinewave and a ringing square
>> wave.  I have about 13 feet of RG174 between the FRS and the measurement
>> equipment so who knows.   This is the "*Rubidium and GPS DO From 
>> China<http://stores.ebay.com/Rubidium-and-GPS-DO-From-China>"
>> *eBay store, which I thought was pretty reputable so I want to make sure
>> I'm not doing anything wrong before I contact the seller, PayPal, etc.* 
>> *There
>> was also a big white sticker covering the whole top of the unit.  I had 
>> to
>> remove it to verify the pinouts and the model information.  Hoepfully 
>> that
>> didn't void my warranty on the $100 paperweight.  Should I let it sit
>> overnight?  Any suggestions would greatly be appreciated.
>> Thanks,
>> Bob, N3XKB
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