[ARC5] "Conversion" or "Perversion" articles?

Sat Oct 20 14:19:41 EDT 2012

One of my first command set transmitter conversions was a unit a set up for Field Day CW operation.

1.  It had a TV transformer power supply which developed about 425 VDC with then avant guard silicon rectifiers
2.  I wired the 5v rectifier filament winding in series with the 6.3 vdc windings for an almost 12vac filament scheme for the command set tubes wired for 12v
3.  I regulated the VFO plate at 105 vdc with a VR105
4.  I used an RFC decoupling scheme in the VFO cathode so I could key the vfo w/o a relay.
5.  I removed one 1625 as I didn't need much power given the FD location on top of Kneeland Mountain in Humboldt County, CA with many redwoods to support a good dipole
6.  I included a cathode bias resistor to bias the single 1625 into the AB1 range with that stage running running all the time with some idling current ( not keyed)  I did have a standby switch to turn off the final HV in the receive mode (also switched the antenna TR switch.. So it was not a full break in scheme.  I don't recall the cathode bias resistor value, but it was taken from the Tube Manual for a 6L6 AB1 scheme.  The 1625 screen was developed with a resistor from the plate supply.
7.  I puttered around with various swamping resistors and played around with using only half of the driving secondary on the vfo inductor to minimize the drive to the 1625 and to keep it out of grid current to minimize TVI or interference to adjacent operators at our FD site on 40 meters and up.  
8,  The command set was a 4-5.3 unit modified to operate on 80 meters with mostly moving padder caps.  And yes, I had to put the side arm knob on the final tuning padder.  I don't recall any inductor mods but in the end the rascal would light up a 25 watt light bulb to a moderate brilliance. 

All this experimenting paid off and I damn near worked all states on the bottom of the 80 meter band.  BTW the receiver I had at the time, a Navy DAQ, was a 20 inch cube of aluminum whose cabinet could have been used as a storage container for nearly 20 Command set transmitters.

Of course this was  50 years ago and had it not been for this project I would not have the great memory nor the use of the gadget for a few years after that as I progressed to more advanced projects that also relied on the surplus marketplace for affordable parts.  Many of the Command Set modifications were based on articles in CQ magazine and the Command Set Handbook(s).  

Bob, Ke6f

-----Original Message-----
From: Geoff <geoffrey at jeremy.mv.com>
To: Mike Everette <radiocompass at yahoo.com>; arc5 <arc5 at mailman.qth.net>
Sent: Sat, Oct 20, 2012 9:12 am
Subject: Re: [ARC5] "Conversion" or "Perversion" articles?

Excellent post Mike. The most important part IMO is 

"Yes, that 522 went to the Big Surplus Store In the Sky... so did several other 
projects.  But the important thing was, I LEARNED FROM THEM."

Since that was the intended purpose when all the surplus was released that 
trumps, by far, all the whining and chest beating of a noisy minority on here.

At 15 did I know why my various ARC-5 receivers didnt have much speaker volume? 
Hell no but I had enough interest to go into the US Navy, become an ET, and make 
a very nice career in both the USNR and civilian life and retiring as a 
Senior/Principle Engineer in microwave and above R&D and with considerable 
experience in DOD related companies. 

Do I care that I and others back then modified WW2 surplus and some that was not 
possible to return to as built? Again hell no!

The whiners seem to be mostly from a decade or more later and many were likely 
still pooping in their diapers when I tried to learn something completely on my 
own. They are still doing much the same on here.

Until these crybabies learn to accept that we are all here because of ARC-5 
interest, no matter at what level, there will always be these type of threads.

----- Original Message ----- 
From: "Mike Everette" <radiocompass at yahoo.com>
To: <arc5 at mailman.qth.net>
Sent: Saturday, October 20, 2012 10:20 AM
Subject: [ARC5] "Conversion" or "Perversion" articles?

> After having played with surplus gear for many years, I am of the opinion that 
many of the so-called conversion articles of the late forties and early fifties 
weren't worth the ink they were printed with; let alone the cost of the paper.
> 
> Indeed, some of them were proof of the old adage: "Ignorance can be fixed, but 
STUPIDITY is forever."
> 
> I never, ever had a problem with audio from a Command receiver, SCR-522, 
BC-348 or BC-312/342 unless it was due to something I caused through "trying 
out" one of those "conversions."  My first BC-348, which I still have, was a 
particularly long-suffering device.  I must have tried every "conversion" 
written including splitting the gain controls, adding an audio stage (and then 
marveled that it worked no better than the original design, same volume!), 
making the crystal filter "variable phasing," changing the RF amp tubes for 
higher gain etc etc etc -- but I had the good sense, or luck, to save all the 
original parts in a special box.  I ultimately rebuilt the 348 as stock, and it 
still works very nicely -- better than with the "mods."
> 
> One mod I never tried, but wanted to, was to make the BC-348 a dual conversion 
receiver by wiring an IF strip using BC-453 85 KHz IF cans into the dynamotor 
well.  I'll bet that worked nicely.  And, I saw what I believe to be the 
PROTOTYPE for that conversion for sale on eBay several years ago.  Unfortunately 
I wasn't the Lucky Winner.  
> 
> As for whether anything we ever did with surplus gear mattered, or made a 
difference -- YES, it did!  One of my transmitter projects involved a Navy 
TBW-4.  This transmitter is, putting it mildly, a BEAST.  But, I got it working 
and in the process learned a great deal about transmitter design and operation.  
And, about components and their parameters.  And, a HEALTHY RESPECT FOR HIGH 
VOLTAGE.  In fact, much of what I learned from the experience proved to be of 
great benefit when I began working in the broadcasting business a few years 
later... I was into everything from 1 KW jerkwater daytimers to 50 KW major 
market stations.  AM and FM.
> 
> I learned quite a bit about VHF gear with the SCR-522, which after 
considerable reworking of the front end, became a very hot 2-meter receiver... I 
even morphed it into a dual-conversion, tunable FM receiver by installing a 
crystal-controlled converter stage to move the 12 MHz IF down to 455 KHz and 
dump it into the Permakay Filter and low IF from a Motorola pack set railroad 
portable unit.  One thing I learned from that was about air currents in a room 
affecting tuning capacitors.  You had to hold your breath to keep signals in the 
passband.  But, it did sort-of work.  And yes, my experience with the 522, the 
VHF ARC-5 and other gear served me well while working in avionics and land 
mobile radio.
> 
> Yes, that 522 went to the Big Surplus Store In the Sky... so did several other 
projects.  But the important thing was, I LEARNED FROM THEM.
> 
> Those who do nothing but spend wads of money to accumulate "artifacts" and 
then do nothing but stare moon-eyed at them, bow before them as unto gods, and 
maybe occasionally dust them, learn NOTHING.  Except perhaps this:
> 
> How does one make a small fortune with a radio collection?
> 
> Start with a large fortune.
> 
> 73
> 
> Mike
> W4DSE
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