24/07/2012 13:14
My Racal Dana 9908 can take a 1 Mhz external reference. Inputting my
Thunderbolt at 10 MHz works, but shifts the decimal point over. I am
not sure if this has any other detrimental effects as to accuracy or
other? What's the easiest way to have a 1 MHz reference from the
Ready made or to be built? Use a divide-by-10 (7490-like) set to divide
with 50% duty cycle or divide by 5 then by 2.
On Tue, Jul 24, 2012 at 2:18 PM, Chris Wilson ch...@chriswilson.tv wrote:
24/07/2012 13:14
My Racal Dana 9908 can take a 1 Mhz external reference. Inputting my
Ready made or to be built? Use a divide-by-10 (7490-like) set to divide
with 50% duty cycle or divide by 5 then by 2.
Thanks for the reply Azelio.
Sorry, should have said, ready built, got too many half finished jobs
on the go right now. FAR too many according to my wife
Will be
Mine are not handy, so I'm not sure it has 50% output duty, but the Ballantine
6130A Time Mark Generator is a potential candidate. It's not much more than a
chain of 7490 dividers fed from a 10MHz source, and has a (non-nut) ovenized
oscilltor built in. Even has synchronized multipliers that go
A Tektronix DD501 will do divide by 10, or any number from 2 to 9.
-John
===
Mine are not handy, so I'm not sure it has 50% output duty, but the
Ballantine
6130A Time Mark Generator is a potential candidate. It's not much more
than a
chain of 7490 dividers fed from
A Tektronix DD501 will do divide by 10, or any number from 2 to 9.
-John
Thanks, was hoping for something as a permanent, small and cheap
fitting, standalone. Don't really want to tie up my 7233 running
something to run something else IYSWIM? Was hoping China Town would
have the
I would do a dead bug construction and insert inside the equipment and mark it
10MHz reference.
All your instruments will be sync.!
Raj, vu2zap
At 24-07-2012, you wrote:
Ready made or to be built? Use a divide-by-10 (7490-like) set to divide
with 50% duty cycle or divide by 5 then by 2.
On
Unfortunately, the TAPR T2-Mini divider
(http://www.tapr.org/kits_t2-mini.html) can't quite get to 1 MHz from 10
MHz with the PIC divider chip due to limitations in the chip architecture.
However, nothing says you couldn't dead bug in a decade divider chip
in place of the PIC, and let the
I think the HP 5087 Distribution Amp has a card that will do divide-by-ten.
-John
==
Unfortunately, the TAPR T2-Mini divider
(http://www.tapr.org/kits_t2-mini.html) can't quite get to 1 MHz from 10
MHz with the PIC divider chip due to limitations in the chip architecture.
Chris,
my vote is for the David Partridge 'time-nuts' frequency divider that
was discussed and optimised here in detail some time ago.
It divides everything you might need from the 10 MHz input. There are
separate outputs for 10 MHz, 5 MHz, 1 MHz, and one that can be
configured for 100 kHz /
John,
That's interesting to me. What exactly are the actual structural limitations of
[that] pic?
-CH
On Jul 24, 2012, at 7:55, John Ackermann N8UR j...@febo.com wrote:
Unfortunately, the TAPR T2-Mini divider
(http://www.tapr.org/kits_t2-mini.html) can't quite get to 1 MHz from 10 MHz
On Tue, Jul 24, 2012 at 7:28 AM, Chris Wilson ch...@chriswilson.tv wrote:
A Tektronix DD501 will do divide by 10, or any number from 2 to 9.
-John
Thanks, was hoping for something as a permanent, small and cheap
fitting, standalone. Don't really want to tie up my 7233 running
Chris,
my vote is for the David Partridge 'time-nuts' frequency divider that
was discussed and optimised here in detail some time ago.
It divides everything you might need from the 10 MHz input. There are
separate outputs for 10 MHz, 5 MHz, 1 MHz, and one that can be
configured for 100
Chris,
A PIC requires 4 clock cycles per instruction which limits the
maximum output rate a PIC can provide as partial instruction
times can't be used. With a 10 MHz input each instruction takes
400ns and if duty cycle isn't an issue nop instructions can be
added each loop to extend the cycle
TVB can give a better answer, but in general the number of clock cycles
required per instruction limits the minimum divide ratio.
Tom whipped up a special PIC to get the highest possible output rate for
a set of tests we were doing, and given the 20 MHz maximum input clock,
we got about 800
Hi
With some micros you can play with the PWM outputs to get a bit faster than the
instruction cycle would allow. There are always constraints (like binary
division) on that as well.
Bob
On Jul 24, 2012, at 5:21 PM, John Ackermann N8UR wrote:
TVB can give a better answer, but in general the
From: Chris Wilson ch...@chriswilson.tv
Ready made or to be built? Use a divide-by-10 (7490-like) set to
divide with 50% duty cycle or divide by 5 then by 2.
Thanks for the reply Azelio.
Sorry, should have said, ready built, got too many half finished jobs
on the go right now. FAR too many
I agree - just tack a CMOS or LSTTL decade divider right inside the
equipment for now, then provide a fancy divider in your distribution
amp if you get around to it.
It's funny that entire extra instruments and programming
microcontrollers are being discussed to replace a simple fifty year
18 matches
Mail list logo
