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Where the 10MHz reference is located on E8285A?

 

Greetings!
I want to know if my HPE8285A has the high-precision reference unit. Where should it be located? If it doesn't have it, how can I install? Ok, I know I can use an external GPSDO signal

Thanks
Alexandre, PU2SEX

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It should be listed in options somewhere on the menu screens or on a sticker on the back. The High Precision unit is a big plug in metal box about 10 cm square and 1 cm deep metal can along with several plug in units in a row ...RF etc boards.
I had units with high precision and regular oscillator. I swapped the high precision unit and I really did not notice any difference.?
You calibrate the oscillator from a menu function using an external?time base?I think the time base has to be several hundred MHz as I recall, I might be wrong about the freq of external time base. I use another HP unit with a GPS disciplined osc in it to cal the 8395 at 500 MHz.
I concluded that at the normal price of a high precision time base for this unit, an external?time base was much more accurate and cheaper. The actual oscillator in the high precision time base is not very big and I think it is a temp comp osc not an oven.

Wally KC9INK

On Tuesday, March 16, 2021, 11:08:04 PM EDT, Alexandre Souza <alexandre.tabajara@...> wrote:


Greetings!
I want to know if my HPE8285A has the high-precision reference unit. Where should it be located? If it doesn't have it, how can I install? Ok, I know I can use an external GPSDO signal

Thanks
Alexandre, PU2SEX

---8<---Corte aqui---8<---
---8<---Corte aqui---8<---
 

Find a list of ATSC pilot frequencies.? They are usually network disciplined.? Try several - I see 2hz variation between them in my area.? This way you can judge the warmup drift of your instrument.? For Ham use, TCXO is plenty good if you calibrate it at lab temp, and you wont have to worry about warmup drift with the OCXO.? If I am really picky, I will let the OCXO warm up for at least 1 hour, but maximum stability is reached by 2 hours.? At room temp, the TCXO will be ready for use while the OCXO will have to wait at least 20 mins to do better.

My other answer was to get one of those surplus e-bay 105243 OCXO, build up a clean power supply for it and leave it running all the time. This is as accurate as warming up the OCXO in my 8920a for 2 hours.

I wonder if there are any issues with keeping the internal OCXO warm with 9v or so from an external dc supply with diode isolation?
 

There are 2x OCXOs in the E8285A. High stability and CDMA which is pll locked to the high stability. The location is shown on page 89 of the E8285-90033 Agilent Technologies E8285A CDMA
Mobile Station Test Set Assembly Level Repair manual. You'll find it online. Download it and learn more about the inside of your gear. I use an GPS locked OCXO to calibrate all my analyzers specifically the Samsung EP92-01704A UCCM-LP. You can pick them up on eBay quite easily. They were used in cellphone towers to synchronize the network. The E8285A manual indicated above also gives detail on how to calibrate the frequency and measurement unit of your analyzer. 73s de chris zl1cvd

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