It can be overkill, I've to see what I've around here, but I was talking about taking out the +5V from the +12V 8A supply.
My thinking is provide one Input for 12V and then divided by the UCCM, Arduino and Raspberry.
UCCM - 5V 2.5A for start on OCXO warmup
Arduino - 5V 500mA with TFT
Raspberry 3 - 5V 1A
This should be around 12V 4A or maybe 3A
+12V 4A to one LT1085 feeding the UCCM, picking up the same +12V feeding one LM7805 to the Arduino, and another to the Raspberry.
Wow. This is a great thread! I've learned a lot of info about the Symmetricom GPSDO here. Mine came with the oil on the board and a few damaged caps. All of which were repairable. One thing I noticed is that it really is sensitive to having a LOS view to the satellites. I had my GPS antenna (A lucent antenna with 26db of gain) on a pole in some trees. It had a terrible time even getting a fix. It took hours. I moved the antenna to the unused chimney on the roof of the house and it made a world of difference. Before it would only track about 4 or 5 satellites and they were never stable. Now it tracks about 8-10 on average and they are stable. So, I had mine running for a day or so and I got an error that the frequency control was at the upper limit. The Fc to the OCXO was pegged at 5.1v. I also was getting low OCXO current warnings. I removed the OCXO and poped the cover off and reflowed all of the connections on the lower board. It's a single oven if anyone wants to know. I put it back together and it ran for a few days and then I got the same error. So, I happened to see an exact replacement OCXO on Ebay: 222113598831. I ordered one because is was at a reasonable price and it was not overseas. Well, the "new" oscillator arrived a few days ago and it was defective. I sent it back and got a refund. I wasn't going to take another chance on a replacement fearing that maybe they all came from a bad lot. I'm wondering if anyone else has had trouble with the Symmetricom OCXOs? I bought a used Oscilloquartz OCXO and hopefully it will arrive next week and will be a drop in replacement.
(My working board came from waikeionline_uk)
Also, he refunded me $20 from my original payment to pay for the return. The tracking on the return shipment shows that he still did not pick them up (but that could be an error of course). Oh well, you get what you pay for I guess...
I bought a used Oscilloquartz OCXO and hopefully it will arrive next week and will be a drop in replacement.
I bought a used Oscilloquartz OCXO and hopefully it will arrive next week and will be a drop in replacement.my Oscilloquartz OCXO 8663-XS did not work as an exchange although beeing compatible in its dimensions it is not with its Vref and Vefc.
Kutte
I bought a used Oscilloquartz OCXO and hopefully it will arrive next week and will be a drop in replacement.my Oscilloquartz OCXO 8663-XS did not work as an exchange although beeing compatible in its dimensions it is not with its Vref and Vefc.
Kutte
Rats! I saw the Vref and Vefc were around 8v and 0-10v respectively. Did you use a different OCXO? Do you know if the Vref output is actually used?
I don't think it would be too difficult to scale them with a couple op-amps using the 12v as the supply. Or maybe a single shunt resistor for the Vref output since it has about a 1k impedance and then just a x2 op-amp for the Vefc.
Rats! I saw the Vref and Vefc were around 8v and 0-10v respectively. Did you use a different OCXO? Do you know if the Vref output is actually used?
I don't think it would be too difficult to scale them with a couple op-amps using the 12v as the supply. Or maybe a single shunt resistor for the Vref output since it has about a 1k impedance and then just a x2 op-amp for the Vefc.
Some guys put some kind of foamy on all 4 sides of the OCXO, but from what I've read on the Time nuts list, this will make the OCXO incapable of heat regulation, because the heat would have no place to go, making the OCXO temp rise so the OCXO will lower the EFC to compensate, then it decompensating the OCXO.
Some guys put the foamy but leave about 3 to 4cm around the OCXO, but it will lead to the same result.
Try to read some of this on Time nuts list.
Still waiting for my antenna to show up here, it-s been in the customs for about 10 days, but the rest is here.
hi to all,
received my Symmetricom board yesterday. As to be exspected some damage could be seen. On the top side xtal y1 is missing, inductor L20 was ripped off. On the botton side capacitor C26 and resistor R83 were missing.
R83 could be easily identified as 103 (10kOhm), C26 is in neighbourhood of C27 which I measured as 1.2 uF. I put in 0.56 uF as a provisory measure.
Inductor L20 I measured as 5uH and replaced with a new one. ...
regards Goetz