I took all of the advice and made what I thought was the most sensible thing.
Not using switches of any kind at all. Out of TICC in a case, N connector
comes out as input (1 pps). I made an external box that houses 5/10MHz to 1
pps. They are completely independent. No possibility for cross
When I first got my TAPR-TICC one of the first tests that I did with it was to
put a coil of RG-58 in the freezer then measured the prop delay as it warmed
up. I posted a plot on the list. I didn't have a temp sensor in the coil,
though.
Hi
As far as the coax goes, termination is a good idea. As far as the signal goes
… maybe not so much ….
Using 5V logic as an example:
If you build up a driver that has a 50 ohm source impedance, you have a (so
far) do-able project. The
output delivered into a light load could be the same as
On 7/6/19 8:34 PM, Glen English VK1XX wrote:
Hal, Good point.
and I have never seen a spec for phase stability for Cat-7 cable !
for RG58, OR OTHER polyethylene, might be up to 150ppm /deg C. maybe as
good as 10 ppm/deg C for some LMR.
With 1000 feet of cable might be an issue for fine
Being a Ham and experienced 10base-2, I'm rather careful with termination but
thanks for the reminder. I've decided to use coax relay 18GHz that I have a
lot of, and purchased cheaply. That way, there is no question.
---
(Mr.) Taka Kamiya
KB4EMF / ex
Hi Taka,
I made an 1:8 multiplexer with TE HF3 relays. They are specified up to 3
GHz, but the 'tree'-design has log2(8) = 3 levels - i.e. the signal always
passes through three relays.
in practice I got around 1 GHz -3dB bandwidth, which I think is OK for 1PPS
In that case, my suggestion is think of them all as transmission lines
in coax. terminate as needed.
Others here will also have points I have missed I am sure, or
alternative equally valid suggestions.
beign critical (maybe I am being over critical) :
watch out also for reflections from
I should have mentioned this clearly earlier, but all converting and switching,
then measuring happens in ONE 2U rack case. Length of each cable is minimal.
I thought mention of TICC would make it sort of clear but it didn't.
I have LOTS of coax relays. I'll use them. It's a gross overkill
---
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
On Sunday, July 7, 2019, 12:00:52 AM EDT, Glen English VK1XX
wrote:
Hal, Good point.
and I have never seen a spec for phase stability for Cat-7 cable !
for RG58, OR OTHER polyethylene, might be up to
Hal, Good point.
and I have never seen a spec for phase stability for Cat-7 cable !
for RG58, OR OTHER polyethylene, might be up to 150ppm /deg C. maybe as
good as 10 ppm/deg C for some LMR.
With 1000 feet of cable might be an issue for fine stuff. a few nano
seconds each way over
> coax cables are in general NOT PHASE STABLE with temperature, either.
Is twisted pair any better?
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I thoroughly agree with Bob.
Suggest converting 1pps into something hardy like LVDS or LVPECL and
using twisted pair , Cat 7 (individually shielded pairs and controlled
skew cable) , or a pair of coax (balanced coax). The balanced signals
will deal with the chance of power supply
Hi
Indeed the fast rise time of just about any modern digital signal gets energy
up into the GHz region. Isolation wise, the
simple answer is often to just disable the signal when not in use. In a one at
a time system, that takes care of cross
talk / feed through. There are a lot of “always
I am trying to come up with a viable design to encase TICC along with 10MHz ->
1 pps converter. My plan is to share the input connector and switch in/out the
converter.
1 pps, although technically a 1Hz signal, rise time and duration is awfully
short on some sources. I'm sure constituent
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