[R-390] R-390 Digest, Vol 106, Issue 19
Edward
navydude1962 at yahoo.com
Sat Feb 16 05:48:31 EST 2013
Maybe Dave Curry can supply the demand? Unless he's no longer with us.
Sent from my iPhone
On Feb 16, 2013, at 5:35, r-390-request at mailman.qth.net wrote:
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> Today's Topics:
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> 1. Filters (quartz55)
> 2. R-390A Filters (KA9EGW)
> 3. Filters (quartz55)
> 4. Re: Filters (Bob Camp)
> 5. Filters (mlmccauley at att.net)
> 6. Re: Filters (Bob Camp)
> 7. Filters (Jim Haynes)
> 8. Re: Filters (mlmccauley at att.net)
> 9. Re: Filters (Bob Camp)
>
>
> ----------------------------------------------------------------------
>
> Message: 1
> Date: Fri, 15 Feb 2013 16:40:03 -0500
> From: "quartz55" <quartz55 at hughes.net>
> To: <r-390 at mailman.qth.net>
> Subject: [R-390] Filters
> Message-ID: <C1A642090BCB4B718B4684B18FE399B3 at DAVE>
> Content-Type: text/plain; charset="iso-8859-1"
>
> I have my 2K and 4K filters removed from the IF.
>
> The 4K appears dead in the IF. Input and output windings show 51 ohms, to ground the output measures 34Meg, the input measures 370Meg.
>
> 2K in the IF appears to have high loss compared to 8 and 16K filters. Input and output windings show 53 ohms. To ground output measures infinity. Input measures 5.3Meg/1Meg depending on which way I use the leads.
>
> 82pf caps appear good.
>
> Any recommendations for taking them apart? I've read the articles and the sites with pictures on removing the ends, but I'm still a bit confused about when heating them, how do I keep them from blowing apart with the build up of heat? I see a nubbin on one end of the filters, right in the center, output end, does that cover a hole? Or should I just drill a hole in one end before heating them? They appear to be the later filters, buff colored so there's no connection of the input and output ends.
>
> http://i251.photobucket.com/albums/gg287/DogTi/R390A/filters_zpsb692cc43.jpg
>
> ------------------------------
>
> Message: 2
> Date: Fri, 15 Feb 2013 16:00:34 -0600
> From: KA9EGW <ka9egw1 at britewerkz.com>
> To: r-390 at mailman.qth.net
> Subject: [R-390] R-390A Filters
> Message-ID: <511EB002.3090502 at britewerkz.com>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
> I am surprised nobody has tooled up an aftermarket crystal, ceramic or
> mechanical filter [especially 4K as that seems to be the most
> susceptible to end-of-life failure] as has been done for the power
> supply caps and some other unobtanium parts...if I had the time I would
> do it, but with a family member in termina decline I don't.
>
> And whatever happened to Tim Curry's replacement filters?
>
> Are the I/O Z's on current manufacture filters compatible?
>
> 73, Brian KA9EGW
>
>
> On 2/15/2013 3:40 PM, quartz55 wrote:
>> I have my 2K and 4K filters removed from the IF.
>>
>> The 4K appears dead in the IF. Input and output windings show 51 ohms, to ground the output measures 34Meg, the input measures 370Meg.
>>
>> 2K in the IF appears to have high loss compared to 8 and 16K filters. Input and output windings show 53 ohms. To ground output measures infinity. Input measures 5.3Meg/1Meg depending on which way I use the leads.
>>
>> 82pf caps appear good.
>>
>> Any recommendations for taking them apart? I've read the articles and the sites with pictures on removing the ends, but I'm still a bit confused about when heating them, how do I keep them from blowing apart with the build up of heat? I see a nubbin on one end of the filters, right in the center, output end, does that cover a hole? Or should I just drill a hole in one end before heating them? They appear to be the later filters, buff colored so there's no connection of the input and output ends.
>>
>> http://i251.photobucket.com/albums/gg287/DogTi/R390A/filters_zpsb692cc43.jpg
>> ______________________________________________________________
>> R-390 mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/r-390
>> Help: http://mailman.qth.net/mmfaq.htm
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>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>
>
>
> ------------------------------
>
> Message: 3
> Date: Fri, 15 Feb 2013 18:18:47 -0500
> From: "quartz55" <quartz55 at hughes.net>
> To: <R-390 at mailman.qth.net>
> Subject: [R-390] Filters
> Message-ID: <BDF13E4EA09F4D4DBA44226763D1711D at DAVE>
> Content-Type: text/plain; charset="Windows-1252"
>
> Yes, I'm suprised no one has come up with a viable replacement myself after all this time, but hey. I suggested an op amp filter, but it was poo-pooed at that freq, but with the new op amps we have these days, I wouldn't think 455 would be all that hard, but what do I know? DSP would be too much of a project.
>
> I'm sure the switch is fine, but it's really hard to tell with the filters in the circuit. Now that they're out I'll check for sure, but everything except ohms to ground measures the same with a good IF module I have, and removing the 3 filters has raised the resistance to ground on the agc line on the IF with the bad filters.
>
> I was measuring my filters with a Fluke 189.
>
> ------------------------------
>
> Message: 4
> Date: Fri, 15 Feb 2013 20:16:46 -0500
> From: Bob Camp <ham at kb8tq.com>
> To: "r-390 at mailman.qth.net Group" <r-390 at mailman.qth.net>
> Subject: Re: [R-390] Filters
> Message-ID: <6B501384-0CB8-4DFD-A445-1D02BF72162A at kb8tq.com>
> Content-Type: text/plain; charset=us-ascii
>
> Hi
>
> If you are going to do an op amp filter, you need to do the math first. Op amps are fine for something that's 40 KHz wide and stable to a few KHz. One percent at 455 KHz is 4.5 KHz. The individual resonators in the 4 KHz filter are set up to within < 400 Hz of their desired frequency.
>
> Bob
>
> On Feb 15, 2013, at 6:18 PM, quartz55 <quartz55 at hughes.net> wrote:
>
>> Yes, I'm suprised no one has come up with a viable replacement myself after all this time, but hey. I suggested an op amp filter, but it was poo-pooed at that freq, but with the new op amps we have these days, I wouldn't think 455 would be all that hard, but what do I know? DSP would be too much of a project.
>>
>> I'm sure the switch is fine, but it's really hard to tell with the filters in the circuit. Now that they're out I'll check for sure, but everything except ohms to ground measures the same with a good IF module I have, and removing the 3 filters has raised the resistance to ground on the agc line on the IF with the bad filters.
>>
>> I was measuring my filters with a Fluke 189.
>> ______________________________________________________________
>> R-390 mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/r-390
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:R-390 at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>
>
>
> ------------------------------
>
> Message: 5
> Date: Fri, 15 Feb 2013 19:50:12 -0600
> From: "mlmccauley at att.net" <mlmccauley at att.net>
> To: R-390 at mailman.qth.net
> Subject: [R-390] Filters
> Message-ID: <511EE5D4.8050900 at att.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>
> 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
>
>
>
>
> ------------------------------
>
> Message: 6
> Date: Fri, 15 Feb 2013 21:05:15 -0500
> From: Bob Camp <ham at kb8tq.com>
> To: "r-390 at mailman.qth.net Group" <r-390 at mailman.qth.net>
> Subject: Re: [R-390] Filters
> Message-ID: <2850FF90-D735-4BF4-B2E9-C2B5234EB07D at kb8tq.com>
> Content-Type: text/plain; charset=us-ascii
>
> 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
>>
>>
>> ______________________________________________________________
>> R-390 mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/r-390
>> Help: http://mailman.qth.net/mmfaq.htm
>> Post: mailto:R-390 at mailman.qth.net
>>
>> This list hosted by: http://www.qsl.net
>> Please help support this email list: http://www.qsl.net/donate.html
>
>
>
> ------------------------------
>
> Message: 7
> Date: Fri, 15 Feb 2013 20:18:23 -0600 (CST)
> From: Jim Haynes <jhhaynes at earthlink.net>
> To: r-390 at mailman.qth.net
> Subject: [R-390] Filters
> Message-ID: <alpine.LFD.2.03.1302152010500.14170 at earthlink.net>
> Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII
>
> Rockwell-Collins still makes mechanical filters, but it's my understanding
> they use a different principle from the older ones, and also that the
> interface requirements are different.
>
> I see by a web page that they make a low-cost series for use in 455 KHz
> IF circuits, with bandwidths of 300, 500, 2500, 5800, 7000 and 10000 Hz.
> Naturally they don't say what "low" means in cost.
>
> jhhaynes at earthlink dot net
>
>
> ------------------------------
>
> Message: 8
> Date: Fri, 15 Feb 2013 20:23:24 -0600
> From: "mlmccauley at att.net" <mlmccauley at att.net>
> To: R-390 at mailman.qth.net
> Subject: Re: [R-390] Filters
> Message-ID: <511EED9C.6030507 at att.net>
> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
>
>
> 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
>
>
>
> ------------------------------
>
> Message: 9
> Date: Fri, 15 Feb 2013 21:35:32 -0500
> From: Bob Camp <ham at kb8tq.com>
> To: "r-390 at mailman.qth.net Group" <r-390 at mailman.qth.net>
> Subject: Re: [R-390] Filters
> Message-ID: <774F85C7-FBA5-41F2-8306-FB22A7AAD7ED at kb8tq.com>
> Content-Type: text/plain; charset=iso-8859-1
>
> 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
>>>>
>>>>
>>>> ______________________________________________________________
>>>> R-390 mailing list
>>>> Home: http://mailman.qth.net/mailman/listinfo/r-390
>>>> Help: http://mailman.qth.net/mmfaq.htm
>>>> Post: mailto:R-390 at mailman.qth.net
>>>>
>>>> This list hosted by: http://www.qsl.net
>>>> Please help support this email list: http://www.qsl.net/donate.html
>>> ______________________________________________________________
>>> R-390 mailing list
>>> Home: http://mailman.qth.net/mailman/listinfo/r-390
>>> Help: http://mailman.qth.net/mmfaq.htm
>>> Post: mailto:R-390 at mailman.qth.net
>>>
>>> This list hosted by: http://www.qsl.net
>>> Please help support this email list: http://www.qsl.net/donate.html
>
>
>
> ------------------------------
>
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>
> End of R-390 Digest, Vol 106, Issue 19
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