EMRFD Message Archive 8432

Message Date From Subject
8432 2013-03-31 18:16:13 Ronald RiemVis Programmable Attenuator
Hello All,

I am looking for a way to make a attenuator which I can control by a PIC.

I want 3 decades with 20dB 1 decade with 10dB and one 6 dB and 2 dB and 1dB
in series.
I want be able to make selections in attenuation.

Has anyone a solution for me?

Frequency must be within 1 dB untill 20 MHz

Gretings,

Ronald


[Non-text portions of this message have been removed]
8436 2013-03-31 18:40:37 Paul Anderson Re: Programmable Attenuator
There are digital potentiometers.

On Thursday, March 28, 2013, Ronald RiemVis wrote:

> Hello All,
>
> I am looking for a way to make a attenuator which I can control by a PIC.
>
> I want 3 decades with 20dB 1 decade with 10dB and one 6 dB and 2 dB and 1dB
> in series.
> I want be able to make selections in attenuation.
>
> Has anyone a solution for me?
>
> Frequency must be within 1 dB untill 20 MHz
>
> Gretings,
>
> Ronald
>
>
> [Non-text portions of this message have been removed]
>
>
>
> ------------------------------------
>
> Yahoo! Groups Links
>
>
>
>

--
Paul Anderson
VE3HOP
wackyvorlon@gmail.com
http://www.andersonloco.com


[Non-text portions of this message have been removed]
8437 2013-03-31 18:57:56 Jerry Haigwood Re: Programmable Attenuator
How about Omron RF type relays (G6 type). Electronic Goldmine has some for
$1.39 each. It is old school but works.

Jerry W5JH

"building something without experimenting is just solder practice"







8440 2013-03-31 22:02:08 Kerry Re: Programmable Attenuator
I second the Omrons but be careful to get ones suitable for RF; there seem to be a lot of different Omron relays marked G6 but with different suffixes.

The G6Z series is rated to 3 GHz but they are not cheap (about $10 each in VK) , especially considering that you will require a lot of them as they are SPDT type.

This would be a very expensive attenuator!

Panasonic/Matsushita make a cheaper VHF relay; the DS2-E series. These would work and are cheaper (about $2.50 in VK).

DIP-cased reed relays may work; I have used SPDT PRMA 14-pin devices to switch IF filters at around 10 MHz.

Their data sheet says that they have 1pF inter-open-contact C and 2 pF contact-to-ground C; that's a Z of about 4 000 ohms at 20 MHz so should be OK.

If you propose to use non-RF-type relays, get one and test its isolation; even just measuring inter-contact and stray C will give you a good idea of its suitability.

Kerry VK2TIL.
8442 2013-04-01 00:13:16 Ashhar Farhan Re: Programmable Attenuator
How much attenuation are you looking for. Lower attenuation figure
maybe easier to achieve electronically.
I had used regular DIP relays with disasterous results. The relay
coils were picking up AM broadcast QRM! I bypassed them with 0.1uF,
but the attenuation was still quite modest. Ultimately, I used
separate relays (both throws paralleled) on each side. A little
expensive, but liveable.
The neat trick is to wire the relays such that the bypass
connection(the wire used to pass the signal when the step is off) must
be grounded at both ends. This ensure smaller leak.
- farhan

On 3/28/13, Ronald RiemVis <ronald.riemvis@gmail.com> wrote:
> Hello All,
>
> I am looking for a way to make a attenuator which I can control by a PIC.
>
> I want 3 decades with 20dB 1 decade with 10dB and one 6 dB and 2 dB and 1dB
> in series.
> I want be able to make selections in attenuation.
>
> Has anyone a solution for me?
>
> Frequency must be within 1 dB untill 20 MHz
>
> Gretings,
>
> Ronald
>
>
> [Non-text portions of this message have been removed]
>
>

--
Sent from my mobile device
8443 2013-04-01 00:56:45 NeilDouglas Re: Programmable Attenuator
Ronald,




Have you considered the AT65-0107 is a TTL compatible 6 bit IC attenuator,
0.5 dB steps to 31.5dB, up to 1GHz.








Regards



NeilD

G4SHJ



_____

8444 2013-04-01 07:15:59 Todd F. Carney / ... Re: Programmable Attenuator
8454 2013-04-03 13:50:57 w5jhjerry Re: Programmable Attenuator
I notice that Electronic Goldmine has the Omron G6Y-1. This relay is rated up to 900 MHz and has a loss of .2db or less at that frequency. They are SPDT type so it would take two relays per attenuati
8456 2013-04-03 23:27:57 Robert Bennett Re: Programmable Attenuator
Have you considered the AS179-92LF?

http://www.skyworksinc.com/uploads/documents/200176G.pdf

They are not expensive.......available from Digikey.

I don't have a reference, but I know that they have been used successfully in a set of HF bandpass filters.

73 Robert G3WKU


----- Original Message -----
8461 2013-04-05 19:50:10 Russ Ramirez Re: Programmable Attenuator
Hi Ronald,

How about a series of broadband transformers to provide the attenuation
steps you desire, selected using a 4066 Quad switch, with the switch
selects either driven by the PIC or latched with a 4042 or similar? The
transformers would have the primaries in-line with the high side of the
secondaries selected using the 4066. The primaries would be a wire running
straight through the toroids to a 50 Ohm load, and the secondaries would be
various turns to yield the attenuation step, e.g. 10T for -20dB. This
approach would be for signals below say 10dBm, but could be adapted for use
with relays (like an auto-tuner) for transmit levels.

Russ
K0WFS

8462 2013-04-05 19:50:10 Ronald RiemVis Re: Programmable Attenuator
Hello Paul,

Yes there are, but then the overall impedance from 50 ohm is not there when
you attenuate.
Greetings,

Ronald


On 1 April 2013 09:40, Paul Anderson <wackyvorlon@gmail.com> wrote:

> **
>
>
> There are digital potentiometers.
>
>
> On Thursday, March 28, 2013, Ronald RiemVis wrote:
>
> > Hello All,
> >
> > I am looking for a way to make a attenuator which I can control by a PIC.
> >
> > I want 3 decades with 20dB 1 decade with 10dB and one 6 dB and 2 dB and
> 1dB
> > in series.
> > I want be able to make selections in attenuation.
> >
> > Has anyone a solution for me?
> >
> > Frequency must be within 1 dB untill 20 MHz
> >
> > Gretings,
> >
> > Ronald
> >
> >
> > [Non-text portions of this message have been removed]
> >
> >
> >
> > ------------------------------------
> >
> > Yahoo! Groups Links
> >
> >
> >
> >
>
> --
> Paul Anderson
> VE3HOP
> wackyvorlon@gmail.com
> http://www.andersonloco.com
>
> [Non-text portions of this message have been removed]
>
>
>


[Non-text portions of this message have been removed]
8466 2013-04-05 19:50:10 Ronald RiemVis Re: Programmable Attenuator
Hello Robert,

Nice you also think about a solution, I need a attenuator from DC to 50 MHz.
I can build myself but miss the information how to switch the sections.

Greetings,

Ronald


On 4 April 2013 14:27, Robert Bennett <robertgjbennett@btinternet.com>wrote:

> **
>
>
> Have you considered the AS179-92LF?
>
> http://www.skyworksinc.com/uploads/documents/200176G.pdf
>
> They are not expensive.......available from Digikey.
>
> I don't have a reference, but I know that they have been used successfully
> in a set of HF bandpass filters.
>
> 73 Robert G3WKU
>
>
> ----- Original Message -----
>
8481 2013-04-06 21:42:24 Ronald RiemVis Re: Programmable Attenuator
Hello Russ,

I think this could solve my problem, torroid's I have many.

Could you make a diagram for me, I don't catch the wiring and switch part

Greetings,

Ronald


On 2 April 2013 22:06, Russ Ramirez <russ.ramirez@gmail.com> wrote:

> **
>
>
> Hi Ronald,
>
> How about a series of broadband transformers to provide the attenuation
> steps you desire, selected using a 4066 Quad switch, with the switch
> selects either driven by the PIC or latched with a 4042 or similar? The
> transformers would have the primaries in-line with the high side of the
> secondaries selected using the 4066. The primaries would be a wire running
> straight through the toroids to a 50 Ohm load, and the secondaries would be
> various turns to yield the attenuation step, e.g. 10T for -20dB. This
> approach would be for signals below say 10dBm, but could be adapted for use
> with relays (like an auto-tuner) for transmit levels.
>
> Russ
> K0WFS
>
>
>