[ARC5] ARC5 Octal Crystals

[D C _Mac_ Macdonald]

For those who have thought that the FT-230 was a crystal, here's a picture of the FT-230 on eBay.  Auction has closed (it's mine now). 
 
http://www.ebay.com/itm/291210649577 
 
As has been stated, this unit plugs into J-1 contained in the recess compartment at the front of the ARA, SCR-274-N, and ARC-5 receivers. 
 
Pin 1 is connected to Pin 3 of J-3 on the rear of the radio.  These two connections end up at the high end of a remote 50 kOhm rheostat that controls sensitivity. 
 
Pin 2 is ground. 
 
Pins 3 and 4 are unused (more later). 
 
Pin 5 is the line for CW-OSC (BFO) shut-off and is also connected to Pin 4 of J-3 going to the rack and a remoted switch. 
 
Pin 6 has + LV (28VDC) (apparently jumpered from Pin 7) to feed the dynamotor at Pin 2 of J-2.
 
Pin 7 is the + LV (28 VDC) fed from Pin 6 of the rack.  
 
Pin 8 is +HV from filtering circuits in the receiver after the dynamotor.
 
It appears that no receiver can be functional without SOME adaptor in that front cavity.
 
I plan to partially disassemble the FT-230 I just won to see if it might be practical to replace the original front panel and then find a small SPST switch and 50 k pot that would fit within the "box."  That should hopefully leave enough space for a 3.5 mm phone jack for audio output. All "mods" to be easily reversible.
 
* * * * * * * * * * * 
* 73 - Mac, K2GKK/5 * 
* (Since 30 Nov 53) * 
* k2gkk hotmail com * 
* Oklahoma City, OK * 
* USAF & FAA (Ret.) * 
* * * * * * * * * * * 
 
 
 
> Date: Sun, 17 Aug 2014 09:14:53 +1200
> From: neilb0627 at gmail.com
> To: bcarling at cfl.rr.com; arc5 at mailman.qth.net
> Subject: Re: [ARC5] ARC5 Octal Crystals
> 
> > Do you know what frequency those marker crystals ....... ran on?
> 
> In case by "ran on" you mean that the crystals operated in an oscillator
> circuit,
> they did NOT.
> 
> When the transmitter tuning knob was rotated to the setting where the VFO
> frequency matched the crystal frequency, the high impedance of the crystal
> caused a very sharp indication in the magic eye tube.
> 
> This indication could be seen either directly by looking down on the tube
> with
> the cover open, or from the front by setting the cover to an appropriate
> angle
> and looking in its mirror. Thus it was (and still is) possible to check the
> dial
> calibration. At all times other than frequency match, the crystal is
> virtually inert.
> 
> 73 de Neil ZL1ANM
> 
> 
> On Sun, Aug 17, 2014 at 1:29 AM, <bcarling at cfl.rr.com> wrote:
> 
> > Thanks John,
> >
> > Do you know what frequency those marker crystals and receiver crystals ran
> > on?
> >
> > Also - does anyone know what radios used hc6u crystals on 200 kHz please?
> > I have several of them I stocked here back when people were asking for
> > them a lot,
> > but I never figured out what radios they were using them in.
> >
> > Also - I am not familiar with the FT-230. I need to learn about that, and
> > what frequencies
> > were used for the receivers.
> >
> > Thanks again and 73 - Brian AF4K
> >
> > On 16 Aug 2014 at 9:21, jmfranke at cox.net wrote:
> >
> > > The octal crystals in the transmitters were not used to directly control
> > the transmitter frequency. They were marker crystals and in conjunction
> > with the 1629 magic eye tubes would indicate when the transmitter VFO was
> > tuned to a specific frequency.
> > > A number of the receiver were crystal controlled but did not use octal
> > based crystals. Two crytsals could be pluged in to wherre the FT-230 was
> > installed on the front panel.
> > >
> > > John  WA4WDL
> > >
> > > ---- bcarling at cfl.rr.com wrote:
> > > > Question: Does anyone have any ARC5 Octal Crystals that they would
> > like reloaded with
> > > > amateur band crystals inside?
> > > >
> > > > Are the ARC5 HF transmitter series basically "straight through" on
> > most models?
> > > > Or do they use doubling etc. to arrive at the transmitted frequency?
> > > >
> > > > If I am not mistaken, some of the radios use VFO control and some use
> > crystals.
> > > > If I have this all wrong please correct me. I am assuming it is the
> > transmitters that use
> > > > crystals for fixed frequency operation, and not the receivers, right?
> > > >
> > > > 73 to all - Brian Carling, AF4K