[SignalOne] CX-7 Filters

[Don Merz]

Contact AF4K. He will grind you all the xtals you want at a reasonable price. AF4K - FT243 RADIO CRYSTALS etc. FOR SALE
  
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AF4K - FT243 RADIO CRYSTALS etc. FOR SALE
 By BC AF4K Home Page  |  |

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73 de N3RHT

      From: Ka9p--- via SignalOne <signalone at mailman.qth.net>
 To: edwa9gqk at yahoo.com; SignalOne at mailman.qth.net 
 Sent: Sunday, January 8, 2017 7:04 PM
 Subject: Re: [SignalOne] CX-7 Filters
   


This list is for discussions regarding collecting, repair, use and sale of Signal/One radios and accessories.

Documentation on Signal/One radios can be found at http://www.hamanuals.com and several other sites on the Web.

.
They are hard to find, I finally got one cw filter by buying a barn find  
radio for about what a filter should cost and still haven't found time to 
test  it...
 
.....but before that I had spent a lot of time looking at the more recent  
ladder filter design articles, and thought if I could find a source of 8815  
khz crystals in quantity it shouldn't be that bad a project, and you could  
make a few of varying bandwidths.......the set up of the radio looks like 
there  is plenty of room for a few homebrew ladder filters.  in fact I was so 
 desperate that I did collect up all the 8 meg FT-241 crystals I could find 
at  hamfests and was going to try to grind them into submission (like in my 
novice  days) to try get 4-6 close enough for a decent homebrew.  Obviously 
I'm  retired with way too much time on my hands, and doubt that would work 
very well,  although it might be easier to get some crystals close enough to 
do a lattice  filter.
 
I have no idea what suitable crystals would cost in quantity but if anyone  
is interested in looking at a quantity crystal order, I'd be interested as  
well....
 
good luck with the hunt.
 
73 Scott ka9p
 
 
In a message dated 1/8/2017 4:28:01 P.M. Central Standard Time,  
signalone at mailman.qth.net writes:



This list is for discussions regarding collecting, repair,  use and sale of 
Signal/One radios and accessories.

Documentation on  Signal/One radios can be found at 
http://www.hamanuals.com and several other  sites on the Web.

.
Hello, Peter,
I also never saw any  satisfactory solutions to additional filters. You may 
have already noticed in  the news letters that the factory ones were less 
than satisfactory due to  filter matching/alignment problems. I also followed 
the issue of trying to add  audio filtering and even found one of the MFJ 
filters at a hamfest for $1!  This was many years after the newsletters ended 
making it all the more amazing  to find one of these filters. After 
studying the letters I decided my best  option was to use a dsp unit I had built 
and used on my Ten Tec Paragon. I  mainly used it for the noise and notch 
functions which the Paragon lacked.  These out board dsp units were popular 
before manufacturers started building  the technology in to the radios.
My unit also offered several very sharp  audio filter choices so I decided 
to use this device which was now sitting  unused. It works great with the 
CX-7 and while it cannot always help with  strong close in interference 
signals, it is plenty good for regular operating.  If you can lay your hands on 
one of these old outboard dsp units that does  notch/noise/filter 
functionality I would do that and not have to cut into the  radio itself. Hope this 
helps.
73 ...  Ed

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