[time-nuts] 5 Mhz to 10 Mhz and 25 Mhz

[Gerhard Hoffmann]

Am 08.09.19 um 14:02 schrieb Paul Bicknell:
> Dear all
>
> Can any one point me in the direction of a circuit that can convert
> 5 Mhz signal to give me 2 outputs one at 10 Mhz and another at 25 Mhz

5 MHz -> 10 MHz is easy.

5 MHz -> 25 is harder. You can use a transistor biased to class B

with tuned circuits at the output, but to get an acceptable efficiency,

you'll have to adjust the collector current duty cycle, which is

f(input power, bias, etc) to keep Mr. Fourier happy.

You'll also need substantial filtering at the output.

Narrow filters are a natural enemy of phase stability.


You can find this & that useful here: 
http://www.wenzel.com/documents/circuits1.htm



For 5->10 MHz, you can use something like the output amplifier

of my OCXO support board V2.0 and operate it in push-push doubler style.

See attachment. The amplifier/doubler is just the narrow strip below the 
SMA

connector in the photo.


-----------------------------------------------------

While I'm at it:

I've got the V2.0 boards just last week and tested it only with a Morion 
MV89A

(on the back side) and the output amplifier in push pull without doubling.

With a 12V supply, it is easy to get +23 dBm out in nice quality. I have

also seen +26 dBm with some distortion. That could probably be healed

with adjusted bias, but for me +23 dBm is plenty. Enough to drive any

ring mixer or Timepod input even through a power splitter.

One could use a 1:4 splitter for 4 outputs with identical phase noise

and still have substantial signal power.

Watch your power meter or spectrum analyzer input. They might burn.


RF Transformers are $1.99 or so at Digikey.  No DIY required.


There are 2 crystal or LC notches to reduce unwanted frequencies.

The Morion MV89 doubles internally from 5 to 10 MHz; on mine I can see

the 5 MHz fundamental on the scope. Every other 10 MHz sine is somewhat

higher or lower. Gives an unsteady scope picture. Uncaring.  :-(


The board can lock the local VCXO to an incoming frequency or 1pps 
reference,

produce a 1pps_out from the VCXO (3V3 CMOS level into 50 Ohms, good enough

for TTL) and indicate the signal level of the incoming ref frequency 
(temp comp. diode

rectifier).


Supported oscillators are HP10811A, Morion, MTI-260, ECOC-2522-100.000-3FC

(affordable 100 MHz SC oven, avail. at DigiKey, abt. €100 ) and some el 
cheapo others.


2FF-Phase detector and 1pps generation are in a $2 Xilinx Coolrunner II. 
There are

strapping options for (5, 10, 100, x)MHz, Vtune sense etc. and optional 
volt. regulators.

There are also lots of unused pins on a 100mil grid for experiments.


At $5 total for 10 boards + transport from PCBway it is cheap enough to 
use it

just for mechanical mounting.


regards, Gerhard


-------------- next part --------------
A non-text attachment was scrubbed...
Name: DSC_0817_gimp.jpg
Type: image/jpeg
Size: 245836 bytes
Desc: not available
URL: <http://febo.com/pipermail/time-nuts_lists.febo.com/attachments/20190909/c03f5700/attachment.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: ocxo_out.png
Type: image/png
Size: 128961 bytes
Desc: not available
URL: <http://febo.com/pipermail/time-nuts_lists.febo.com/attachments/20190909/c03f5700/attachment.png>