[R-390] Filters

[Bob Camp]

Hi

There's also a perfectly good IF output jack on the back of the radio to attach a "gizmo" to. No need to chop up the radio at all. If you get to the point where there are no filters at all, jumper one position and use the IF output…

Bob

On Feb 16, 2013, at 12:12 AM, KA9EGW <ka9egw1 at britewerkz.com> wrote:

> 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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