EMRFD Message Archive 2815

Message Date From Subject
2815 2009-03-29 17:04:04 Chris Trask The Solder Wick Chronicles, Part 2: Updated Noise Blanker
I've made some progress on the design of the noise blanker, finishing
off the details of the noise limiter and the delay line. And this time, I
got the URL right:

http://www.home.earthlink.net/~christrask/Paper020.html

I'll have some serious test data before too long.

Chris

,----------------------. High Performance Mixers and
/ What's all this \ Amplifiers for RF Communications
/ extinct stuff, anyhow? /
\ _______,--------------' Chris Trask / N7ZWY
_
2818 2009-03-29 18:20:23 tim Re: The Solder Wick Chronicles, Part 2: Updated Noise Blanker
It may be too late for you now but the old Tempo 2020 that Henry Radio sold
many years ago had the best noise blanker I've ever used. It had a whole
separate board dedicated just to the noise blanker and worked by matching the
delay through the if amps to the delay through the blanker board. The
blanking pulses worked *very* well without mangling the signal.

If you can find an old 2020 service manual with the board schematics and
circuit descriptions it might provide some useful information.

Of course it was many years ago when I used this xcvr and my ears were perhaps
a lot more tolerant back then!!

tim ab0wr

On Sunday 29 March 2009 07:02:15 pm Chris Trask wrote:
> I've made some progress on the design of the noise blanker, finishing
> off the details of the noise limiter and the delay line. And this time, I
> got the URL right:
>
> http://www.home.earthlink.net/~christrask/Paper020.html
>
> I'll have some serious test data before too long.
>
> Chris
2821 2009-03-30 07:18:32 victorkoren Re: The Solder Wick Chronicles, Part 2: Updated Noise Blanker
You can always use a lumped components network to simulate the transmission line.
For example a 3rd order Butterworth LC LPF with a -3dB cutoff frequency of 100MHz will have a delay of 3.3nS with insignificant attenuation at the 0 to 30MHz frequency range. Cascade 30 such stages and you have the delay you want. The finite Q of the inductors will add some attenuati
2825 2009-03-30 07:47:55 Chris Trask Re: The Solder Wick Chronicles, Part 2: Updated Noise Blanker
>
> You can always use a lumped components network to simulate the
> transmission line.
> For example a 3rd order Butterworth LC LPF with a -3dB cutoff
> frequency of 100MHz will have a delay of 3.3nS with insignificant
> attenuation at the 0 to 30MHz frequency range. Cascade 30 such
> stages and you have the delay you want. The finite Q of the
> inductors will add some attenuation at 30MHz, (1dB for Q=100),
> but it will be still usable.
>

I did look at that, but it would have taken up a lot of board space and would have ended up costing more than the DDD delay line, though much less than a suitable length of good-quality coaxial cable.



Chris

,----------------------. High Performance Mixers and
/ What's all this \ Amplifiers for RF Communications
/ extinct stuff, anyhow? /
\ _______,--------------' Chris Trask / N7ZWY
_