[ARC5] AN/ARC-5 on MF 630 Meters

[Christopher Bowne]

Good on ya Dave re 630 Meters.  I am in the process of getting on that band myself using my BC-191 and it’s low frequency tuning unit.  
I’ve tested it into a 50 ohm dummy load.  In order to get it to load to its rated 190 ma plate current on CW I had to add about 2000pf parallel capacity across the transmitter output.  Doing so raised the max loading plate input from about 125 ma to 190 ma, and the RF wattmeter at the dummy load from 25 watts to 50 watts.  The wattmeter is just a Heathkit HM-102 and it’s calibration is certainly suspect at such a low frequency.  TM 11-800 states rated output at low frequency and HF is 75 watts at a nominal 190 ma plate current.

If you haven’t already, check out 472kHz.org, lots of great information references and links to all things 630 meters.  CW on the band generally in the vicinity of 472-474 kHz.

73 de Chris AJ1G
Stonington CT


Sent from my iPhone

> On Mar 16, 2022, at 22:17, David Stinson <arc5 at ix.netcom.com> wrote:
> 
> ARC-5 on 630 Meters.
> Been meaning to try this for a long time.
> Since I'm not allowed to pick-up anything heavy
> and am on leave to recoup, I got working on this.
> 
> My AN/ARC-5 set has the goodies
> for the T-15 T-16 T-17 MF transmitters.
> 
> https://photos.app.goo.gl/PhueH4gcrP4BWyQ8A
> (Yes I forgot to change the RX Control Box dial.)
> 
> The T-15 will indeed easily go down to 470 KC.
> Mesh the Oscillator cap, leaving about a 25 degree
> angle unmeshed.  472 KC will be at about 505 KC
> on the dial.  The Plate trimmer on mine resonates
> within the range of the set screw.  It's making
> good power, though I can't measure it (scope probe
> broke), but it will light-up a big florescent bulb fully.
> None of the TN-6 loading was used, but did like
> the little neon bulb ;-).  The TX roller coil was at about
> a third, link at about 80%.
> 
> Here is the signal (to a very poor substitute antenna)
> keyed in CW mode with the microphone button.
> received on an SDR receiver about 30 miles distant.
> Lots of QRN:
> https://tinyurl.com/58ywxdt7
> 
> Here's a Video:
> https://tinyurl.com/mru6cd52
> 
> When the docs let me do more, I will replace my storm-
> wrecked "Titanic Antenna" and make some contacts
> on CW.  Gonna be cool.
> 
> GL OM DE Dave AB5S
> 
> 
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