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From: Phil Allison on 20 Mar 2010 01:28

"Glenn Gundlach"
Jan Panteltje

> Better just use some meters of coax cable to delay one period :-)

At 8nS / foot

** Really ?

When did the velocity factor of co-ax go down to 12.7 % ??



...... Phil




From: Candide Voltaire on 20 Mar 2010 06:08
On Mar 19, 9:02 pm, whit3rd <whit...(a)gmail.com> wrote:
> On Mar 19, 4:25 am, Candide Voltaire <candideguev...(a)gmail.com> wrote:
>
> > On Mar 19, 9:21 am, oopere <m...(a)somewhere.net> wrote:
> > > > I'm looking for a passive rc-network which produces a delay of 200ns
> > > > for a 5MHz sinusoidal voltage.
> > > an optimum schematic,... is a degenerate case of RC, with R=0,
> > > C=0 (inexpensive)
> > OK that's correct, do you also have an answer in case we want 180ns?
>
> Depends; do you accept a phase-lead network, or does it have to
> be phase-lag?  A single RC stage can have zero to 90 degrees lag,
> it'd take four or more to get to the 180 ns mark, and there is quite
> a lot of attenuation.  The 36 degree phase lead is easier.

If I understand you correctly you suggest to use a high pass section,
that works indeed with an RC=43.8ns
I get the required delay and the attenuation is around 1.8dB thats
less than 20%. Thanks!
From: John Fields on 20 Mar 2010 08:17
On Fri, 19 Mar 2010 22:06:21 -0700 (PDT), Glenn Gundlach
<stratus46(a)yahoo.com> wrote:

>On Mar 19, 4:25�am, Jan Panteltje <pNaonStpealm...(a)yahoo.com> wrote:
>> On a sunny day (Fri, 19 Mar 2010 09:21:13 +0100) it happened oopere
>> <m...(a)somewhere.net> wrote in <hnvc5q$a5...(a)defalla.upc.es>:
>>
>>
>>
>>
>>
>> >Candide Voltaire wrote:
>> >> I'm looking for a passive rc-network which produces a delay of 200ns
>> >> for a 5MHz sinusoidal voltage.
>> >> Which is the minimum number of RCs to achieve this? Are there some
>> >> schematics optimized for this purpose?
>>
>> >> Candide
>
>>
>> >Since the required delay is a whole period, the answer is yes, there is
>> >an optimum schematic, although it is a degenerate case of RC, with R=0,
>> >C=0 (inexpensive)
>>
>> >Vin----R--�--Vout
>> > � � � � � |
>> > � � � � � C
>> > � � � � � |
>> > � � � � �gnd
>>
>> >Pere
>>
>> Na, C=0 and R=0 is extremely expensive.
>> Impossible to make even.
>> Better just use some meters of coax cable to delay one period :-)
>
>At 8nS / foot that's 25 ft which might cause space problems though it
>would work well. A BAL, Allen Avionics ot Mathey delay line would take
>a lot less space but cost more and not be as easily adjustable. It
>still needs an amp to make up the 6+dB insertion loss - or maybe
>that's acceptable.

---
With c ~ 1ns/ft, coax with a foam polyethylene dielectric having a
dielectric constant of between 1.3 and 1.6 will have a velocity factor
of somewhere between 0.88 (1.14ns/ft) and 0.79 (1.27ns/ft) which, for a
200ns delay, translates into a length somewhere between 175 and 157
feet.

JF
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