[minima] Re: Linear Output Filter Switching
- From: Wayne McFee <nb6m@xxxxxxx>
- To: "minima@xxxxxxxxxxxxx" <minima@xxxxxxxxxxxxx>
- Date: Sat, 1 Feb 2014 12:11:30 -0800
Yes,
and with provision for five filters, 160 meters can be covered, too.
such as
160
80
40-30
20-17
15-12-10
which is the scheme used in the Hardrock 50 amp.
Wayne
> On Feb 1, 2014, at 10:47 AM, Mark G0MGX <mark.g0mgx@xxxxxxxxx> wrote:
>
> very good. That CMOS chip used in the link looks the same as the TTL 74141 -
> but I am no expert.
>
> This does seem to be the way to go.
>
> Mark
> G0MGX
>
>> On 01/02/2014 18:24, mpcharlton@xxxxxxxxxxx wrote:
>>
>> Mark
>>
>> Have a look at this halfway down the page...
>>
>> http://www.vk5tm.com////homebrew/filter/filter.php
>>
>> Mark
>> G6ZQS G-QRP 2247
>>
>>
>>
>>
>> -------Original Message-------
>>
>> From: Mark G0MGX
>> Date: 01/02/2014 17:29:09
>> To: minima@xxxxxxxxxxxxx
>> Subject: [minima] Re: Linear Output Filter Switching
>>
>> Isn't this:
>>
>> http://www.g3ynh.info/digrdout/74141.html
>>
>> exactly what we need to go from Binary outputs on our 3 digital lines to
>> individual relays controlling filters?
>>
>> Mark
>> G0MGX
>>
>>
>> On 01/02/2014 15:26, farhanbox@xxxxxxxxx wrote:
>> > Mark,
>> > There's something not right about the curve. The stopband is quite
>> > nominal. You must get atleast 60 db stop-band.
>> >
>> > Sent from BlackBerry® on Airtel
>> >
>> > -----Original Message-----
>> > From: Mark G0MGX <mark.g0mgx@xxxxxxxxx>
>> > Sender: minima-bounce@xxxxxxxxxxxxx
>> > Date: Sat, 01 Feb 2014 13:47:38
>> > To: minima@xxxxxxxxxxxxx<minima@xxxxxxxxxxxxx>
>> > Reply-To: minima@xxxxxxxxxxxxx
>> > Subject: [minima] Re: Linear Output Filter Switching
>> >
>> > Hi Team
>> >
>> > I've started the output filter Wiki page here:
>> >
>> > http://www.hfsignals.org/index.php/Final_Output_Filters
>> >
>> > and have so far put info on 4, 11 and 19MHz cut off Low Pass Filters. I
>> > am very unhappy with the 19M filter sweep, so will let you guys take a
>> > look before doing any more. The next filter needs to be 30M cut off - we
>> > already have one of those!
>> >
>> > As an aside I have dug out my CD from EMRFD and mine is a 2002 version
>> > of the software which I can't find a filter designer? I can enter values
>> > myself but cant get the software to come up with the filter for me -
>> > hence I have stuck with what I know and used QUCS for my designs.
>> >
>> > I do think that we could still use the existing D5 line for output _*as
>> > well as*_ the existing input filter switching just so long as the line
>> > stays HIGH for > 15MHz and LOW for <= 15MHz. This would give us room for
>> > a 1.8M filter and another if we find we need i. I have only focused on
>> > those highlighted yellow below, but clearly with the three digital lines
>> > we could have up to 8 filters if we needed them.
>> >
>> >
>> >
>> > I personally like the idea of simple logic chip or BCD type logic to
>> > control relays as I feel that we want to avoid more programming and
>> > complexity where it's not needed. The 74LS139 idea is a great one and
>> > probably the way I plan to go, but lets see what we decide.
>> >
>> > I've tried to explain some of this in the Wiki - please take a look and
>> > lets decide between us how we are going to do this part of the project.
>> >
>> > We could of course go with the idea of a separate amplifier completely,
>> > maybe with the tubes others are suggesting! I've never built anything
>> > with tubes....
>> >
>> > Mark
>> > G0MGX
>> >
>> > On 01/02/2014 06:48, Mark wrote:
>> >> Thanks to everyone for the suggestions and ideas.
>> >>
>> >> If we go with 4 filters have we scrapped top band?
>> >>
>> >> I'll try and run some designs for the four suggested filters and build
>> >> some prototypes and stick the results on the wiki.
>> >>
>> >> We can then decide and discuss what we think we should do.
>> >>
>> >> M
>> >> ------------------------------------------------------------------------
>> >> From: Ashhar Farhan <mailto:farhanbox@xxxxxxxxx>
>> >> Sent: 01/02/2014 05:00
>> >> To: minima@xxxxxxxxxxxxx <mailto:minima@xxxxxxxxxxxxx>
>> >> Subject: [minima] Re: Linear Output Filter Switching
>> >>
>> >> Mark,
>> >>
>> >> I have been mulling over this ... and I am trying to balance quite a
>> >> few things here.
>> >>
>> >> 1. Can we make do with just four filters? I have attached a screenshot
>> >> of a simulation I ran (both these programs are available on the EMRFD
>> >> CD). As you can see, a filter can be cut for 7 and 10 mhz. The 7
>> >> mhz's second harmonic at 14 is down by 25db. Which means, if we don't
>> >> distort the linear too much, we can get more 43 db suppression of the
>> >> harmonics. If you guys agree to this , then, I propose as follows :
>> >> 1st filter for 3.5 MHz
>> >> 2nd filter for 7-10 mhz
>> >> 3rd filter for 14-18 mhz
>> >> 4th for 21-28 mhz
>> >> These will have to be three section filters, which is alright. A
>> >> 1-of-4 decoder like 74LS139 could do the switching with just 2 lines.
>> >>
>> >> 2. The switching of the main filters is at variance with this scheme.
>> >> so, we will have to use a dedicated line (as we are doing now) to
>> >> switch these filters.
>> >>
>> >> 3. There is a third line A0 (pin 23) that is unused. this can be used
>> >> to switch in a higher bandwidth filter (more than 10 Khz). with this
>> >> filter, the broadband audio can be fed to an 'SDR' back-end like
>> >> linrad. The serial port can provide the tuning control.
>> >>
>> >> - f
>> >>
>> >>
>> >> On Sat, Feb 1, 2014 at 7:01 AM, Dan Reynolds <on30ng@xxxxxxxxx
>> >> <mailto:on30ng@xxxxxxxxx>> wrote:
>> >>
>> >> I'm not any kind of an expert but could you use a Microchip
>> >> MCP23017 I/O expander on the 5 V side of the I2C bus. I was
>> >> thinking something like I saw on the Tronixstuff page here:
>> >>
>> >> http://tronixstuff.com/2011/08/26/tutorial-maximising-your-arduinos-io-ports/
>> >> Instead of a LED an I/O line could drive a transistor to drive a
>> >> relay(?).
>> >> Then the code could "watch" the frequency and as it changes the
>> >> output line for that particular LPF could be switched.
>> >>
>> >> Or could you use a 74HC595 to accomplish the same thing.
>> >>
>> >> http://tronixstuff.com/2010/04/30/getting-started-with-arduino-chapter-four/
>> >>
>> >> I was going to approximate the Minima front panel with a bare
>> >> bones Arduino and some parts and see what I could dream up.
>> >> I don't really know what I'm doing. I'm just muddling through
>> >> trying to patch bits and pieces together...
>> >>
>> >>
>> >> 73
>> >> Dan -- KB9JLO
>> >> https://sites.google.com/site/on30ng/
>> >>
>> >>
>> >> On Fri, Jan 31, 2014 at 6:10 PM, Wayne McFee <nb6m@xxxxxxx
>> >> <mailto:nb6m@xxxxxxx>> wrote:
>> >>
>> >> Hi Mark,
>> >>
>> >> If the three outputs were set up as you suggest, a Picaxe chip
>> >> could be programmed to control either individual relay driver
>> >> transistors or a relay driver chip like the 2903(?).
>> >>
>> >> I've been using that arrangement for filter selection in a
>> >> homebrew rig.
>> >>
>> >> Or, if one of those output lines could be programmed to output
>> >> a stepped voltage such as that provided by the FT817 for
>> >> bandswitching info, that makes the programming even easier.
>> >>
>> >> Wayne NB6M
>> >>
>> >>
>> >> > On Jan 31, 2014, at 1:24 PM, Mark G0MGX
>> >> <mark.g0mgx@xxxxxxxxx <mailto:mark.g0mgx@xxxxxxxxx>> wrote:
>> >> >
>> >> > Farhan & Team,
>> >> >
>> >> > I can see that we have provision in the schematic for 3
>> >> digital outputs for band selection, but can only see one of
>> >> these (BAND_HI - pin 11 - Arduino D5) being used within the
>> >> function "setBandswitch". It is this function that currently
>> >> selects the LPF used based on frequency.
>> >> >
>> >> > We could set the state of the three outputs based on
>> >> frequency something like this:
>> >> >
>> >> > <Filter Ideas.png>
>> >> >
>> >> > But someone far cleverer than I would need
>> >> to explain how to
>> >> create relay on/off switching based on the logic states of
>> >> the three lines - I have no idea how to do that!
>> >> >
>> >> > If we were to implement something like this was the
>> >> intention to use these additionally switched filters in RX as
>> >> well as TX?
>> >> >
>> >> > I would be interested in your thoughts and ideas on how you
>> >> saw this working before I head down the wrong road with my
>> >> construction!
>> >> >
>> >> > Many thanks,
>> >> >
>> >> > Mark
>> >> > G0MGX
>> >>
>> >>
>> >>
>> >
>
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