[ARC5] BC-459

[J Mcvey]

 One of theing that were overlooked in the conversions in the old days was that the  command radios were designed to run on short antennas, Ie; the length of the plane's fuselage. The transmitters were designed to tune into low z capacitive antennas in a range of about 5 to 12 ohms radiation resistance. The inductor was there to tune out the capacitive component. I use a 1:4 or 1:9 unun auto transformer to get in the 50 ohm ballpark . I get about 50 watts CW with the dynanmotor supply..
The old ham lore says hat the command sets were major TVI generators back in the day. It was probably due to the poor matching techniques.Don't know, I wasn't there...
    On Wednesday, February 26, 2025 at 10:06:24 PM EST, sbjohnston--- via ARC5 <arc5 at mailman.qth.net> wrote:  
 
 Brian wrote:
> I wonder if there is a measurement or a memory problem...
Well, I know how to measure RF power, so we are left with you wondering if I have a memory problem.  

Let's review:  I wrote a casual email which mentioned an alternate approach to the problem of running an ARC-5 HF transmitter on the HP-23 power supply.  My email was meant to convey that it is possible to modify the transmitter to match the power supply, rather than modifying the power supply to suit the transmitter.  My email was not a construction article, though.
Since my project was about 15 years ago, and I am 4000 miles away from that equipment at this time (I  am in Hawaii, but the gear is on a shelf in my main shack is in Wisconsin), time/memory and distance are certainly factors in my story telling.  

It sounds like you have the skills to make such a project happen, so best of luck if you choose to try it.  On the other hand, if your goal was to argue that my idea is impossible, I can confirm you are mistaken.
After all, you said it yourself:
>...the best you could expect from a parallel pair of 1625s, ICAS, is about 108 W
And I saw 100 watts or so CW.  I made no attempt to AM modulate the rig.  Thinking back, I suspect I was running both the oscillator and the PA at higher voltages, and I added adjustable PA bias to set the class of operation.  As I said, I ran the 1625s like they were 807s or 6146s - as used in many ham rigs and the intended load of the HP-23 supplies.
I may have rewired the filaments too, if that wasn't already done in that particular beater transmitter.
The only aspect that might be a memory issue is whether it was a BC-458 or BC-459.   I remember shifting the MO coverage on one ARC-5 transmitter up to cover the low end of 40, and it might have been the one under discussion here.  In which case it would have been a BC-458.

Steve WD8DAS   

sbjohnston at aol.com   
http://www.wd8das.net/   http://af4k-crystals.com/   
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