[ARC5] [Milsurplus] SCR-183/-283 4-5 MC Coil on 75 MTRs

[Mike Everette via ARC5]

Anyone ever seen an SCR-183/283 transmitter modified for crystal control, by the military?

I once had one, and it was traded to "Boatanchor Bob" for some TCS cables... a silver BC-230 with a 4495 kc crystal.  The crystal was a type I've not seen before or since; it looked like a mica capacitor roughly an inch square with big round solder lugs on either side.

73

Mike
WA4DLF

--------------------------------------------
On Sun, 6/29/14, Mike Feher <n4fs at eozinc.com> wrote:

 Subject: Re: [ARC5] [Milsurplus] SCR-183/-283  4-5 MC Coil on 75 MTRs
 To: "'David Stinson'" <arc5 at ix.netcom.com>, "'ARC-5'" <arc5 at mailman.qth.net>, milsurplus at mailman.qth.net
 Date: Sunday, June 29, 2014, 11:58 AM
 
 Mike -
 
 The "doorknobs" are ceramic. 73 - Mike 
 
 Mike B. Feher, N4FS
 89 Arnold Blvd.
 Howell, NJ, 07731
 732-886-5960 
 
 -----Original Message-----
 From: Milsurplus [mailto:milsurplus-bounces at mailman.qth.net]
 On Behalf Of
 David Stinson
 Sent: Sunday, June 29, 2014 11:16 AM
 To: ARC-5; milsurplus at mailman.qth.net
 Subject: [Milsurplus] SCR-183/-283 4-5 MC Coil on 75 MTRs
 
 4-5 MC coil sets for SCR-183/283 transmitters
 (BC-230/-430) are very common, while those that cover 80/75
 Mtrs directly
 can be hard to find.
 The OSC section of the 4-5 MC coil set will operate down to
 around 3750 KC,
 but the PA/Antenna coil is pretty much done at 4 MC.
 http://home.netcom.com/~arc5/SCR-183/coilplate.JPG
 
 You can get the 4-5 MC coil operational down into
 75 meters with a few simple, non-destructive changes.
 Move the Antenna coil tap up to the second turn from the
 top.  Pad the coil
 from the tap down to the bottom using either a 50-100 pFd
 transmitting
 doorknob (Thank you, Mike!)  or big, RF-rated silver
 mica.  
 Don't use a ceramic; too lossy.
 http://home.netcom.com/~arc5/SCR-183/coilpad.JPG
 (yes, yes I know it's sloppy.  I was prototyping,
 guys!)
 
 Assuming you use a 100 pFd RF-rated or air variable cap in
 series with the
 output to feed a 50-ohm load, you'll find the tap for best
 output around
 here:
 http://home.netcom.com/~arc5/SCR-183/coiltap.jpg
 
 You will get about 10-20% less power out than you would with
 the "correct"
 3-4 MC coil, but then most of us don't have that one ;-) A
 working rig in
 exchange for 10% is a good deal.
 
 73 DE Dave AB5S
 
 ______________________________________________________________
 Milsurplus mailing list
 Home: http://mailman.qth.net/mailman/listinfo/milsurplus
 Help: http://mailman.qth.net/mmfaq.htm
 Post: mailto:Milsurplus at mailman.qth.net
 
 This list hosted by: http://www.qsl.net
 Please help support this email list: http://www.qsl.net/donate.html
 
 ______________________________________________________________
 ARC5 mailing list
 Home: http://mailman.qth.net/mailman/listinfo/arc5
 Help: http://mailman.qth.net/mmfaq.htm
 Post: mailto:ARC5 at mailman.qth.net
 
 This list hosted by: http://www.qsl.net
 Please help support this email list: http://www.qsl.net/donate.html