[R-390] Filters

[KA9EGW]

Then too, there is free DSP software for my PC, all I would need is any 
source of audio to feed into my sound card.  As long as at least the 8 
or 16K filter was still viable that would be a possibility.

Sacrilege I know; I'm just trying to think ahead to when even used 
filters are complete unobtanium...or more to the [OT] point what my 
options with my R-388 are, since 354A-1 upgrade-to-R388A/51J4 kits ARE 
unobtanium.

73 de KA9EGW
On 2/15/2013 9:28 PM, Bob Camp wrote:
> Hi
>
> That gets you away from the whole "use a scrap demo board and wire it up" approach.
>
> To answer the question, yes you could come up with a module that drops in where the set of IF filters used to go. Grabbing power by one or another means is likely not to hard.
>
> Once you do all the custom design and boards, cost would be similar to an "attach to a PC" digital radio.
>
> Bob
>
> On Feb 15, 2013, at 10:12 PM, "Scott Overstreet" <scott at becklawfirm.com> wrote:
>
>> Bob---
>> Can you put it all in a box that would fit in place of the mechanical filters and run on available power within that sub assembly?
>>
>> Scott
>>
>>
>>
>>
>>
>>
>> --- Original Message ----- From: "Bob Camp" <ham at kb8tq.com>
>> To: <r-390 at mailman.qth.net>
>> Sent: Friday, February 15, 2013 6:35 PM
>> Subject: Re: [R-390] Filters
>>
>>
>>> Hi
>>>
>>> With the right hardware to target and good design software, the filters are a weekend project code. From scratch the design software stuff likely would run you < $500.
>>>
>>> Bob
>>>
>>>
>>> On Feb 15, 2013, at 9:22 PM, mlmccauley at att.net wrote:
>>>
>>>> Absolutely.
>>>>
>>>> I've seen those come and go. The concept is great, but the market is very limited, hence the cost.
>>>>
>>>> A savvy ham with the proper background could homebrew a very nice filter for a relatively cheap price. Soldering the hardware together would be a fairly easy weekend project, assuming you had a surface mount adapter board for the DSP chip. The software would take many weeks to write and even longer to debug.
>>>>
>>>>
>>>> On 2/15/2013 8:05 PM, Bob Camp wrote:
>>>>> Hi
>>>>>
>>>>> Thus the variety of outboard dsp filter boxes that have shown up over the years. Once you get them into production, the cost is high enough that there is a very limited audience.
>>>>>
>>>>> Bob
>>>>>
>>>>> On Feb 15, 2013, at 8:50 PM, mlmccauley at att.net wrote:
>>>>>
>>>>>> A DSP filter would be an ideal replacement for a mechanical.
>>>>>>
>>>>>> DSP chips that work at 455KHz are readily available for very reasonable $.
>>>>>>
>>>>>> The problem is the software.  To do a nice, flat topped, steep skirt filter would not be a trivial piece of work.
>>>>>>
>>>>>> The upside is that one relatively simple circuit could be made to do everything from super-narrow CW to full bandwidth AM SWL.
>>>>>>
>>>>>> 73,
>>>>>>
>>>>>> Mike, WB5MYY
>>>>>>
>>>>>>
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