[R-390] Vol 28, Issue 3: Dave Curry R-390A filters

Tue Aug 29 16:14:33 EDT 2006

Craig,

I would suggest leaving the variable cap in place, tuning it for maximum 
carrier meter deflection. If you see a small change, but no definite peak, 
try paralleling the fixed capacitor, and see what happens. You may find you 
get a definite peak on the variable cap. If not, try adding a few more 
picofarads (e.g., 5 pF) and keep trying combinations till you see a definite 
peak on the carrier meter.

Too much is left to inference in your query. I have no idea what the article 
in ER says. In fact, I've never seen "ER."

If all else fails, write me direct.

73 de Charlie

Charles A Taylor, WD9INP/4
   Greenville, North Carolina
>
> I have a 6 KHz Dave Curry made R-390A filter and I am about to install
> it in a '68 production EAC.  My question is...if someone out there has
> installed one of these filters before do you leave intact the fixed and
> variable cap that is across the current mechanical filters.  There were
> no instructions about installation and yet I read an article in ER that
> recommends bypassing the fixed and variable cap and hooking it up
> direct.  If anyone has any other information I would appreciate hearing
> from you before I install this in place of my 8 KHz filter.
>
>
>
> Craig W9CLA
>
>
>
>
>
> ------------------------------
>
> Message: 2
> Date: Mon, 28 Aug 2006 13:59:33 -0400
> From: "David C. Hallam" <dhallam at rapidsys.com>
> Subject: [R-390] DA-121/U Dummy Antenna
> To: "R-390 at mailman. qth. net" <R-390 at mailman.qth.net>
> Message-ID: <FAEILKLJLEEAGLJFOKEPGEEMCIAA.dhallam at rapidsys.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Searching through the archives for information about the DA-121/U dummy 
> used
> to connect the SG to the R-390 balanced antenna terminal, I found a
> reference that indicated it was constructed with approximately 100 ohm in
> series with the load and 60 ohm in parallel.  Is this accurate 
> information?
> I want to build one.
>
> David
> KC2JD
>
>
>
>
>
>
>
> ------------------------------
>
> Message: 3
> Date: Mon, 28 Aug 2006 14:42:39 -0400
> From: "WD9INP/4" <WD9INP at isp.com>
> Subject: [R-390] Broken mechanical filter
> To: <r-390 at mailman.qth.net>
> Message-ID: <005601c6cad1$c1930050$504b8441 at your22ca86d5c4>
> Content-Type: text/plain; format=flowed; charset="iso-8859-1";
> reply-type=original
>
> I'd like a mechanical filter to open up. Does anyone have one to get rid 
> of?
>
>
> Charlie
>
>
>
> ------------------------------
>
> Message: 4
> Date: Mon, 28 Aug 2006 21:08:37 +0000
> From: eldim at att.net
> Subject: Re: [R-390] DA-121/U Dummy Antenna
> To: dhallam at rapidsys.com, "R-390 at mailman. qth. net"
> <R-390 at mailman.qth.net>
> Message-ID:
> <082820062108.6784.44F35B54000B695B00001A80215876672003070B040A at att.net>
>
> Content-Type: text/plain
>
> Hello David & Fellow BA'ers,
> If memory serves me correctly, I believe that the DA-121/U was the Dummy 
> Load that was supplied with the military AN/URM-25, AN/URM-26 Series 
> Signal Generators.  It may have been a supplied accessory with one or both 
> signal generators. Hard to believe that it has been over 30 years since I 
> last used on of these.  I just looked at my FEDLOG and it was still lasted 
> as of Mar 05, with two part numbers.  The DA121U and  ENTRON INDUSTRIES 
> LP, FOREST HILLS, N.Y.  Part Nr. 157C4.  National Stock Number 
> 5985-00-557-5717; Last procurement shown is 12/86 at $169.58.  The 
> DA-121/U is a 50 Ohms, 0.5 Watt, 0-50Mhz Dummy Load.  I recall that the 
> URM-25 had four or five different types of attenuators and a Dummy Antenna 
> Load in the lid.  These were a small rectangular aluminum box with a cover 
> secured by 4 screws.  Each one had a BNC Input and Output Connector,  with 
> the exception of one that had a BNC Input, and a Black and a Red Wire with 
> alligator clips for the Output. I also think that
> I hmay
> have seen these in a tubular metal configuration, but don't hold me to 
> that.  The TM, T.O. or NAVSHIPS Manual on these generators had pictures 
> and electrical diagrams.  I'll bet if you go over to BAMA you may find the 
> info that you are looking for.  Good Luck.
> 73,
> Glen Galati, KA7BOJ
> Tacoma,. WA
> eldim at att.net
>
> -------------- Original message from "David C. Hallam" 
> <dhallam at rapidsys.com>: -------------- 
>
>
>> Searching through the archives for information about the DA-121/U dummy 
>> used
>> to connect the SG to the R-390 balanced antenna terminal, I found a
>> reference that indicated it was constructed with approximately 100 ohm in
>> series with the load and 60 ohm in parallel. Is this accurate 
>> information?
>> I want to build one.
>>
>> David
>> KC2JD
>>
>>
>>
>>
>>
>> _____________________________________________________________
>> R-390 mailing list
>> Home: http://mailman.qth.net/mailman/listinfo/r-390
>> Help: http://mailman.qth.net/faq.htm
>> Post: mailto:R-390 at mailman.qth.net
>> Unsubscribe: http://mailman.qth.net/mailman/options/r-390
>
> ------------------------------
>
> Message: 5
> Date: Mon, 28 Aug 2006 18:45:04 EDT
> From: ToddRoberts2001 at aol.com
> Subject: Re: [R-390] Dave Curry R-390A Filters
> To: r-390 at mailman.qth.net
> Message-ID: <493.819c3f3.3224cbf0 at aol.com>
> Content-Type: text/plain; charset="US-ASCII"
>
> In a message dated 8/28/2006 8:30:47 AM Eastern Standard Time,
> Craig.Anderson at saintpaul.edu writes:
> I have a 6 KHz Dave Curry made R-390A filter and I am about to install
> it in a '68 production EAC.  My question is...if someone out there has
> installed one of these filters before do you leave intact the fixed and
> variable cap that is across the current mechanical filters.  There were
> no instructions about installation and yet I read an article in ER that
> recommends bypassing the fixed and variable cap and hooking it up
> direct.  If anyone has any other information I would appreciate hearing
> from you before I install this in place of my 8 KHz filter.
> Craig W9CLA
>
> Hi Craig, it seems the filter should have come with clear instructions as 
> to
> whether to use the existing resonating caps in the R-390A when installing 
> the
> filter. My guess is he used one of the Collins Low Cost Series Torsional
> mechanical filters inside a metal tube the same size as the original 
> filter.
> Collins recommends using fixed 30pf caps (mica preferred) across the input 
> and
> output pins of the filter. I would guess that he installed the correct 
> resonating
> caps already inside the metal filter tube, so there would be no need and 
> would
> actually be harmful to try to re-use the original resonating caps as they
> would detune the filter. Only the original mechanical filters would 
> correctly
> resonate with the original capacitors. 73 Todd WD4NGG
>
>
> ------------------------------
>
> Message: 6
> Date: Mon, 28 Aug 2006 17:56:34 -0700
> From: "Scott Overstreet" <scott at becklawfirm.com>
> Subject: [R-390] Tube Tester
> To: <r-390 at mailman.qth.net>
> Message-ID: <000701c6cb05$fa6e1070$4224f604 at scottengserv>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Tube Tester guys-----
>
> What is a new appearing I-177-B tube tester worth these days?
>
> Scott
>
>
>
>
> ------------------------------
>
> Message: 7
> Date: Mon, 28 Aug 2006 22:32:54 -0500
> From: "Patrick J. Jankowiak" <recycler at swbell.net>
> Subject: Re: [R-390] Repairing broken trimmer capacitors, search
> To: r-390 at mailman.qth.net
> Message-ID: <44F3B566.7060801 at swbell.net>
> Content-Type: text/plain; charset=us-ascii; format=flowed
>
> how to repair small air-viarable capacitors:
>
> http://www.bunkerofdoom.com/cap/fix1/index.html
>
>
>> _______________________________________________
>> R-390 mailing list
>> R-390 at mailman.qth.net
>> http://mailman.qth.net/mailman/listinfo/r-390
>>
>>
>> End of R-390 Digest, Vol 28, Issue 30
>> *************************************
>>
>
>
> ------------------------------
>
> _______________________________________________
> R-390 mailing list
> R-390 at mailman.qth.net
> http://mailman.qth.net/mailman/listinfo/r-390
>
>
> End of R-390 Digest, Vol 28, Issue 31
> *************************************
>
> 