[R-390] R 390A Line Filter Trial

Thu May 1 16:38:37 EDT 2014

At one time, I made several adapter plates for the CorCom filters.  They were a simple piece of flat (1/8") aluminum with a correctly-shaped hole for the filter and holes for the 2 sets of mounting screws.  They worked well and did not involve any permanent modifications to the radio.

I suppose if one is good enough with a just a drill and a file, a person could make one of these without too much effort.  Mine were fabricated using a CNC plasma cutter that helped get all the holes in place such that the CorCom's face lined up with the existing hole (which is kind of critical since the IEC plugs are just small enough to fit inside the existing hole) but enough play in the other holes would make that possible if you're off a bit on aligning the holes.

Regards,
Barry - N4BUQ

----- Original Message -----
> From: "rbethman" <rbethman at comcast.net>
> To: r-390 at mailman.qth.net
> Sent: Thursday, May 1, 2014 3:21:10 PM
> Subject: [R-390] R 390A Line Filter Trial
> 
> This was posted by Glenn Scott WA4AOS, in Feb 2011.
> 
> Folks that are looking at line filter replacement really ought to
> look
> into this.
> 
> The Corcom line filter method is the one used by Tisha and Les
> Locklear.
> 
> Bob - N0DGN
> 
> 
> 
> Hi Group,
>    I am putting a kit together to replace the old leaky Corcom line
> filters used in the R 390A's  with new Hospital grade Corcom filters.
>   The problem is mounting a good quality filter with better specs
>   than
> the original within the existing real estate.
>   I came up with a solution using existing holes, a mounting plate
>   with
> standoffs. This is a very tight fit but easy to install.
>   The filter will mount behind the PTO and is raised above the wiring
> harness runs in the rear. A rubber hole grommet comes with the kit to
> feed the  line cord to the filter. The filter will additionally
> include
> 3 Varistors and a CL-80 current limiter already installed.
> I was not able to find a Corcom or any other  line filter solution
> that
> would mount where the original filter mounted but this solution is
> VERY
> WELL DONE and commiserate with the excellent quality within the 390A
> Receiver.
> All kits will be pre assembled, tested and burned in for at least 1
> hour
> before shipping.
> 
> My prototype filter kits are installed in three R 390A receivers
> presently and the installations were perfect as well as professional
> looking.
>   I am looking for 5 volunteers who have R 390A receivers to take a
>   kit
> at MY COST, install them and give me feedback.
> Already, I know the kit fits into Motorola, Amelco and EAC R 390A's.
> I
> would like to hear from folks who have other built R 390A's  for the
> trial.   I prefer engineers, technicians or competent long term users
> of
> R 390A's for the evaluation trial period. No skills beyond operating
> a
> screwdriver are required but I am looking for professional feedback.
> 
> 
> Of course, the usual warnings about working with any line voltages
> apply.You know, unplug the receiver first, capacitors hold charges,
> wear
> goggles, gloves, hazmat suites, rubber souled shoes, have 911 people
> online the entire time you work, seriously they love R 390A's too,
>  and
> all of the usual safety stuff we all practice daily.. Oh, keep one
> hand
> in your back pocket and a carrot in your left ear too. So, if you
> electrocute yourself to death during installation, don't sue me
> because
> you weren't' warned. Actually, I would prefer not hearing from you if
> you kill yourself putting this kit in... Just saying.. .
> 
> 
> 
>   Later, I will offer these kits to users of this reflector ONLY, at
>   a
> discount for a short period of time before I list the kits on eBay
> and
> my website.
>   I would like the filters kits installed and reports back within a
> month. Please don't request a trial filter if you are NOT SERIOUS
> about
> quickly installing it and reporting your observations to me and the
> users of this reflector. if there are any unforeseen issues, let's
> find
> out now..
> 
> 
> Installation is simple and should not take more than an hour;
> instructions will be included. You simply remove the bottom cover and
> the old Corcom filter. Mount the hardware to the chassis and install
> the
> filter, No soldering will be required. The kit will also include a
> new
> line cord and plug with the aforementioned mounting parts.
>   So far, I see no reason why this kit would NOT fit into any
>   iteration
> of the R 390A receiver but there are some minor variations in
> machining.
>     If all goes well, I will offer these to reflector users around
>     the
> first of May. I am having the small chassis plates CNC machined this
> week and should have them next week. I will offer a full refund
> including shipping to the participants of the trial evaluation if not
> pleased with my kit or certainly if it will not fit
> some variation of machining within the R 390A.
> I plan to post some pics in the next week or two for others to view.
> Additionally, I will post some pics of line hash in and out of the
> filter.
> 
> 
> 
> The evaluation will help me understand any installation issues before
> listing these kits are offered to the general boat anchor community
> on
> eBay and elsewhere.
> 
> Please don't beat me up about changing the looks, or the filter isn't
> necessary, or it's not original,.or why didn't I choose a so and so
> filter. If you have a better mouse trap, build it.
> I gotta tell you, it was very time consuming to fit this or any other
> filter in the prototype stage. My first 5 ideas and attempts did not
> work out for one reason or another.
> 
> >From my perspective, the kit is 100% reversible, prevents people
> >from getting shocked due to differences in potential between the
> >390A chassis and ground.
> I also strove for this to be a professional solution and not be a
> Micky
> Mouse, kludge attempt at fix something; I see my share of sorry mods
> almost every week. I treat these receivers with great respect and am
> trying to help with a known problem.
> 
> 
> Thanks  in advance for reading this post and your assistance to help
> with this project. If you think you might want a filter kit in May,
> please hold off letting me know until the trial is over. As with the
> Fowler manual copies I sold to readers of this reflector last summer,
> about 120 something copies all over the planet, I will make good on
> my
> offer to list these kits here at a discount for a short period of
> time.
> 
> 
> If you are interested in a trial kit at my cost, will install it
> quickly, report your observations and are technically competent to
> electrically and mechanically critique this kit please contact me at
> my
> email address listed below, Additionally, first consideration will go
> to
> owners of 390A variations other than Motorola, Amelco and EAC
> built 390A Receivers. Tell me which 390A you have and a little about
> your capabilities.
> 
> Glenn Scott WA4AOS
> DSM Labs
> 
>   My  email address: (((>>>>>>>>>>   glenn @ dsmlabs dot com
> <<<<<<<<<<<<)))
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
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