[time-nuts] 10MHz to 80MHz frequency multiplier suggestions
g4hup at btinternet.com
Mon Jan 31 21:48:08 UTC 2011
Yes, of course the multiplication plan is a little different, but in the circuit
I linked the basic multiplier is a doubler from 10 to 20MHz, that produces a
comb of 2f products. The design as presented has BPF's to select the 5th
harmonic, and I was simply suggesting that by replacing these with 80MHz BPF's
the same simple circuit would also be useful for the other respondent who wanted
that frequency rather than 100MHz. As Rick has subsequently suggested, 3
cascaded doublers would achieve the 80MHz requirement very well, but of course
they will not solve the 100MHz problem. For 100MHz you can easily do it in two
diode multipliers - one to 50MHz (x5) and a doubler to 100MHz. But that's now
two diffferent circuits, and I was looking at the $10 option..
I'm well aware that time nuts is probably the very worst reflector on which to
post a 'simple' solution! However, it was, as I thought I had made abundantly
clear, my thoughts for the $10 solution - I fully accept Bruces' comments about
the ACMOS jitter issues, and as always it is up to the user to do his own
homework as to suitability. I'm also aware that it is very easy to become
'over-focussed' on specs, and forget what the original job was to do! Since
neither respondent was specific about what they are trying to measure or receive
with their SDR's, or the ADC to be used, no-one can give meaningful guidance,
but there are many who can tell you the best way to do it!
I'm coming from the position that Robert Watson-Watt, of UK radar development
fame, held - of course everyone wants the best, but that will take forever/be
expensive. They would be very happy, and probably not tell the difference from
that if given the second-best solution - so he aimed to deliver the third-best
solution as a starter, and work towards second-best, on the basis that this
would have 'something operational' in the shortest time.
From: Chris Albertson <albertson.chris at gmail.com>
To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
Sent: Monday, 31 January, 2011 20:35:57
Subject: Re: [time-nuts] 10MHz to 80MHz frequency multiplier suggestions
On Mon, Jan 31, 2011 at 11:06 AM, dave powis <g4hup at btinternet.com> wrote:
> Have you seen http://www.timeok.it/files/10_to_100_mhz_multiplier.pdf ? ...
> Although the design is for 100MHz, changing the band pass filters to 80MHz
> will give you that as your output,
80Mhz sounds close to 100Mhz. But look at the prime factors 80 =
2*2*2 while 100=2*5. With a 10X multiplier you are forced to do 2*5
but in an 8X multiplier you can double three times (2*2*2).
Redondo Beach, California
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