[time-nuts] Thunderbolt power requirements

[Bob kb8tq]

Hi

The better you regulate the 12V, the better the TBolt will function. 
The OCXO will be very unhappy outside a +/- 0.5V region. It really
wants something well regulated (like at the couple of millivolts level).

Depending on exactly what era OCXO your TBolt has in it and how well
it is still functioning, ppb level changes for a few percent delta supply are
not unexpected. 

Bob

> On Jan 31, 2020, at 12:29 PM, Brian Lloyd <brian at lloyd.aero> wrote:
> 
> I am in the process of getting my "time box" finished. It has three
> frequency/time references: a T-bolt, an LPRO-101, and the Chinese NTP/10MHz
> server. Distribution of 10MHz and 1pps is via a TADD-1 and TADD-3
> respectively. I have a Microsemi 58536A distribution amp for GPS. (I do
> have one other full-time consumer of GPS and one other part-time consumer
> of GPS.) I would like everything to run from a +12VDC supply to facilitate
> avoiding power outages. The LPRO-101 is powered by a 12V-to-24V switcher
> followed by a brute-force LC filter to clean up the PSU noise, so it is
> effectively happy with anything from 9-16V.
> 
> My main +12V supply bus is a 100AH gel-cell that is being float charged at
> about 13.2V but may be up to +14V during charge and down to +11V during
> discharge. I want to run everything from this bus. No problem for the
> Chinese NTP server, the TADD's, or the LPRO-101 with its upconverter.
> 
> The wild-card in all this is the power for the T-bolt. It needs +5, +12,
> and -12. I currently am powering it from the mains using a 3-output supply.
> That doesn't allow for conveniently running from battery power. Obviously
> the +5 needs to be pretty tightly regulated but not sure about the +12 and
> -12. Can I cheat and run the +12 from my 12V power bus or does it need to
> be more tightly regulated?  If necessary, I can boost to +15 and then
> regulate down to +12.
> 
> I suspect the primary use for +12V is the oven. If the oven controller is
> analog using something like a FET or BJT as the control element for the
> heater, supply voltage should be pretty much a non-issue as these devices
> have a constant current for a given base/gate drive, thus pretty well
> decoupling the heater current from the supply voltage.
> 
> Of course I can derive -12V using an isolated switching module. Anyone know
> the -12V current requirement of the T-bolt off their heads? (Yes, I know, I
> can take everything apart and stick an ammeter in series with each leg but
> if someone knows, I can avoid having to do that. Yes, I am being lazy.)
> 
> Thanks in advance.
> 
> -- 
> 
> 
> 
> Brian Lloyd
> 706 Flightline
> Spring Branch, TX 78070
> brian at lloyd.aero
> +1.210.802-8FLY (1.210.802-8359)
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