[time-nuts] Synthesized Signal Generator query

[Steve - Home]

I had a recent email exchange with PTS. I have a PTS 160 SK01G serial number 1A 8428. The output drops off rapidly below 70 KHz. It doesn’t match the manuals available online as it has .1Hz resolution but without the number of DM modules the manual says it should have. Instead it has a couple of DM modules and another module that apparently performs all the functions of multiple DM modules.

I emailed PTS about the possibility of acquiring a manual that matches my unit and the response was:
“Sorry, don't routinely offer complimentary support or complimentary manuals.

More to the point: PTS 160 has a specified lower limit of 100 KHz, no "fixing" possible to obtain outputs lower than that and not malfunctioning.

If the failure is occurring when setting certain 10 KHz steps but at output frequencies above 100 KHz, we'll need to see the unit and the repair cost for a unit of that vintage is $2500.

If you'd like the unit repaired, feel free to contact us, but we are not able to respond to any other inquiries on how to fix your unit.“

I didn’t ask for anything “complimentary” and would have been happy to pay a reasonable price for a manual matching my unit. Maybe explaining to them in my email that I’m a hobbyist and not a million dollar a year buyer was not a smart thing to do but I prefer to be upfront when making requests for information. 

If I felt the need, for $2500 I could buy a good assortment of PTS synthesizers on eBay and swap parts to my heart’s content. 

I’ve discovered the output amplifier rolls off quickly below 70 KHz so my unit is working correctly and I just need to switch over to a 3325B for the lower frequencies.

Steve
WB0DBS



> On Mar 7, 2019, at 8:59 PM, John Ackermann N8UR <jra at febo.com> wrote:
> 
> A couple of comments about the PTS units...
> 
> While the potential noise floor is very low (depending on the quality of the reference oscillator), there can be significant spurs depending on how many non-zero digits you have dialed in.  With the analog multiply and mix architecture, the more digit stages are in use, the more spurs you get above the low noise floor.
> 
> The lower frequency units tend to have better noise than the ones with higher frequency ranges.  The PTS X10, 040, and 160 models are the quietest if you can live with their upper frequency limits (10, 40, and 160 MHz respectively).
> 
> There's also one very tricksie version out there that is particularly interesting for time-nuts -- the PTS250/SX51 where the SX51 option is a switchable divider that turns a 250 MHz synthesizer with 1 Hz resolution into a 25 MHZ synthesizer with 0.1 Hz resolution, and a significant phase noise improvement.  Its noise floor is around -145 dBc/Hz, while the other units are in the -125 to -135 range.
> 
> I have a bunch of measurements of PTS boxen at
> https://febo.com/pages/pts_synth/
> 
> (And, I'm getting ready to sell a few of the too-many PTS boxes in my lab, including an SX51... look out for a notice in the next week or so.)
> 
> John
> ----
> 
>> On 3/7/19 7:15 PM, Alex Pummer wrote:
>> that is a relative low noise synthesizer
>> Programmed Test Sources PTS 160 Frequency Synthesizer
>> 73
>> Alex
>>> On 3/7/2019 11:04 AM, Richard (Rick) Karlquist wrote:
>>> 
>>> 
>>>> On 3/7/2019 8:56 AM, Didier Juges wrote:
>>>> 
>>>> 
>>>> The king of low close-in noise are the HP8662 (990MHz) and HP8663 (2GHz?)
>>>> by about 20dB at 1kHz compared to the 8644A
>>>> 
>>>> Didier KO4BB
>>> 
>>> When I worked at Agilent, my lab had a half dozen HP8662's and some 63's.  They were not useful for any kind of high performance clock requirement, unless we divided them down with, for example, a Centellax (now Microchip) divide by 8 to 511 eval board.  That was SOP in those days.
>>> 
>>> If you just want 100 MHz, there are inexpensive 100 MHz VCXO's
>>> (about $25 at D/K or Mouser) that will blow the doors off of
>>> an HP signal generator.  You can phase lock them to a 10 MHz OCXO
>>> if necessary.  Besides 100 MHz, there are various other frequencies
>>> available.  See Crystek and Abracon, etc.  These VCXO's put out
>>> CMOS logic signals, so you have to convert sine to square.
>>> 
>>> Rick N6RK
>>> 
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