Atwater Kent Set Model 40 and Speaker Model E-3
By Random73
February 2015
Electrically Restored Model 40, February 2015
Prologue
I bought this set, unrestored, for $40.00 at a swap meet sometime
in early 1990s. At purchase I only knew that
The set was dusty and dirty inside,
The power supply unit showed signs of having been messed with,
The cabinet had severe paint scratches, as seen in the photo above, and some kind of varnish overcoating, but no dents.
The power cord was brittle and frayed.
A few parts were missing; o A cartridge-type resistor, o Some fasteners, o The fine-tuning knob, and o Four of the seven tubes.
I did not know what the matching speaker was supposed to be.
Chapter 1. First Efforts
The three tubes that came with the set were a DeForest UX-480
and two RCA UX-226s. Their filaments tested OK for continuity.
My first orders, to Antique Electronic Supply, were for replica
Atwater Kent manuals and the missing tubes.
There are three necessary manuals; 1) the Service Manual, 2) the Parts List manual, and 3) the Electrical Values
manual;
I ordered RCA brand new old stock tubes, including a UX-280, not only to have as spare for the DeForest UX-480,
but also so that my entire 7-tube complement could be
RCA brand.
I disconnected wiring as necessary to remove the power supply
unit and the chassis from the cabinet. Some of their mounting
hardware was missing. See my disassembly procedure in Appendix
A of this report.
To inspect the power supply unit, I unsoldered wires as necessary
to remove the terminal board from the top of the power supply
assembly. There are several resistors on the underside of this
board. Both of the cartridge-type resistors tested way out of
spec. The various wire-wound resistors tested OK.
With the terminal board out of the way, I saw easily that the
pitch filling had been attacked with some kind of sharp tool,
such that there was apparent damage to the audio choke. However,
the power transformer and the filter choke continuities tested
OK.
The power supply housing is divided into three compartments.
The power transformer is in the one next to the UX-280, the filter
choke in the middle, and the audio choke, three B+ filter
capacitors, and two other capacitors in the third. I removed
the UX-280 socket from the power supply. Then I tilted the unit
upside-downwards on a pie tin, and heated it in a gas oven to
about 250o to soften the pitch. I extracted the defective audio
choke and the capacitors in two big, gooey globs. Unfortunately,
the power transformer moved in the softened pitch, such that
its four wires to the UX-280 socket would no longer reach the
socket terminals. Then I put this project away for many years,
due to work and family priorities. I resumed the work in late
2007.
Chapter 2 December 2007- Serious Restoration Work Resumes
Tuesday, Dec. 4, 2007- Thinking that I might be able to repair
the audio choke, I immersed the choke in a Goof-Off solvent
bath to dissolve the pitch glob. After 12 hours in Goof-Off I
transferred the choke to a bath of mineral spirits. I could now
discern a square piece of insulating paper stuck to the bottom
side of the choke.
Wednesday, Dec. 5, 2007- I separated the insulating paper from
the choke. I unsoldered wiring from the choke and returned the
choke, paper insulator, and wires to the mineral spirits bath.
I ordered a brass fine-tuning vernier and main tuning knob from
an E-Bay vendor. The vendors vernier knob photo matched most
of the model 40 photos that I saw on internet.
Thursday, Dec. 6, 2007- I removed the choke from the mineral
spirits bath. The choke and paper insulator were now very clean.
Practically all of the pitch was gone. The sharp-object damage
to the audio choke was very apparent;
DAMAGED AREA-BROKEN WINDING
Now I could see several visible breaks in the choke winding.
I concluded that the choke was not repairable, and that I would
need to find a substitute part.
Saturday, Dec. 8, 2007-
1. Resistance checks using Fluke model 79 digital multimeter,
as compared to specified values in the Atwater Kent manuals;
The audio choke is open circuit, as expected due to the visible damage to the windings, BAD
The 2nd interstage audio transformer, part #7661, had open primary winding and good secondary winding,
BAD.
Power supply o cartridge resistor, #13047
12.45 M vs. specified 65 k BAD o cartridge resistor, #9424
307 k vs. specified 12.5k BAD o tapped wire-wound resistors (3), #9434
13.3 & 13.4 vs. 10 & 10 OK 12.2 & 11.4 vs. 10 & 10 OK 12.2 & 11.4 vs. 10 & 10 OK
o tapped wire-wound resistor, #13538
2300 vs. specified 2200 OK
727 vs. specified 625 OK [but I had problems with this part several months later]
Chassis o RF Grid #1 resistor #8439
380 vs. specified 350 OK o RF Grid #2 resistor #8439
386 vs. specified 350 OK o RF Plate resistor, #13369
3100 vs. specified 3000 OK o Detector grid resistor #8195
specified 2M MISSING
I decided to use a Stancor model A-3850 universal audio output
transformer to replace the defective audio choke. Its primary
DC resistance measured 464, which is reasonably close to the
specified 550 for the audio choke. The secondary of the
transformer stays unconnected, except see discussion later for
option to use the secondary to drive a low-impedance modern
speaker.
2. Capacitance checks using Fluke model 79 digital multimeter,
as compared to values specified in the Atwater Kent manuals;
Specified Measured
Single Bypass #9575 .3F 450V 2.7F BAD
Double Bypass #9928 .3F 200V 1.6F BAD
.3F 200V 1.6F BAD
.05F 400V 1.6F BAD
Phone Condenser #9598 .002F 500V .00185F OK* * This OK assessment of #9598 would later prove to be wrong.
3. I attempted to repair the original ON-OFF switch, which I
already knew was defective (Chapter 1). For backup, I had
previously ordered a very similar looking switch from Antique
Electronic Supply, but it did not have the brass finish. The
original switch can be disassembled by drilling out the pin rivet
flares. See exploded view below;
My cleaning and repair attempt was not completely successful,
and I dont know why. I could not get the switch to reliably
show continuity in the ON position, so I decided to go with a
replacement switch that I ordered several years earlier.
Sunday, Dec. 9, 2007-
I will need to reheat the unit in the oven, so that I can pull
out the four wires to the UX-280 socket, just enough so that
they can be re-soldered to the socket pins.
More resistance checks;
Power transformer
o primary 8.9 OK
o B+ secondary 480 OK
o 5V filament secondary 0. OK (The other secondaries to be tested later, using reduced
voltage on primary, because ohmmeter readings not
reliable in 1 regime)
Filter chokes 700 each OK
From studying internet photos I learned that the main tuning
knob on my set was actually from a model 42 set.
Wednesday, Dec. 12, 2007-
The dial knob and vernier that I ordered came today. The knob
had the right number scale but was not the right color. It was
brown instead of black. I decided to use the model 42 main tuning
knob until I can obtain the proper one. The rubber tire on
the vernier was as hard as a rock. I replaced it with a vinyl
grommet, Waldom part #KG-404, which fit perfectly and works just
fine. The grommet descriptor on the box says 5/16 inch screw
size, and 7/16 inch chassis hole size.
I put the power supply unit in the oven, right side up in a pie
pan, and set temperature to 325o to soften the pitch. I pulled
the wires, to the UX-280 socket, about inch outwards from the
case, to their original positions. Tonight, after all these
years, I re-installed the UX-280 socket. It was too dark for
me to re-solder the wires this night.
Friday, Dec. 14, 2007-
I re-soldered the wires to the UX-280 socket.
I re-soldered the power transformer B+ center-tap to its original ground lug.
I used mineral spirits to clean pitch off of the lip and inner
surface of the power supply housing. This pitch residue was left
over from the first oven treatment that I did years earlier to
remove the audio choke and capacitors.
I tested the volume control without completely removing it. It
seemed OK, but maybe a little scratchy according to the
multimeter. A few squirts of Contact cleaner seemed to help some.
I tested the power transformer today, by applying 12 volts AC
to the primary, from a salvaged yard lights transformer, and
then measuring all secondary voltages using the Fluke model 79
multimeter. Then I scaled all of the measurements by the factor
that scales the primary to 110 Volts.
Measured Scaled
Primary 12.7 Volts 110V (Specified)
B+ Secondary 63.1 Volts 546V OK
Rectifier Filaments 0.613 Volts 5.3V OK
RF / 1st AF Filaments 0.184 Volts 1.6V OK
Detector Filaments 0.283 Volts 2.5V OK
2nd AF Filaments 0.532 Volts 4.6V OK
The original three B+ power supply filter capacitors were
non-polarized paper type rated 400 volts, either 1.0F or 1.5F depending on which source document you believe. I decided to
use non-polarized 1.5F @ 630 volt polyester replacements from Antique Electronic Supply. They fit nicely inside the
compartment where the originals were, along with the replacement
audio choke and two other polyester replacement capacitors
(.47F @ 400 volts each).
I created an accounting of the various missing #8 and #10 fastener
hardware items. All were machine bolts, nuts, and lock washers.
Saturday, Dec. 15, 2007-
I tested the A-3850 universal output transformer secondary just
to make sure there were no short circuits. I used the same method
as for the power transformer, applying 12 volts AC to the primary
of the A-3850. All secondary taps measured reasonable voltages
OK. I realized that, as an option, one could connect the secondary
of the A-3850 to a modern low-impedance speaker instead of using
the original output circuit and an antique high-impedence
speaker. I determined (using the data from the above-mentioned
test and from the UX-171A data sheet) that an 8 speaker should
connect to secondary terminals 4 and 6;
Replacement of the 2nd Audio Interstage Transformer
Sometime in the past I ordered the P-T156 replacement audio
interstage transformer from Antique Electronic Supply. They
claim it as equivalent to the Stancor A53C interstage
transformer, which has a 1:3 primary-to-total secondary turns
ratio. The secondary center-tap of the P-T156 will remain unused
and I taped it over securely.
There is a ground lug that was under one of the mounting fasteners of the original 2
nd audio interstage transformer.
There are three connections to this lug;
o Green wire from power supply harness o Blue wire from 1st AF transformer secondary o Blue wire from 2nd AF transformer secondary, which will
become a green wire from the P-T156
Pin 3 of the UX-171A socket (grid) has the black wire from the original 2
nd AF transformer, and will take the other
green wire from the P-T156.
Pin 2 of the UX-226 1st AF socket (plate) has a green wire from the original 2
nd AF transformer, and will take the blue
wire from the P-T156
The black/red wire from the power supply harness is connected to the yellow wire from the original 2
nd AF
transformer, and will take the red wire from the P-T156.
I decided not to try and re-use the case of the original 2nd AF transformer, at least until all other restorations
have been completed and the set has been proven to work
OK. So for now, the new transformer and the old ground lug
are held in place by the original hardware. See photo below;
THIS IS AN IMPEDENCE TRANSFORMATION CALCULATOR FOR
CHICAGO STANDARD TRANSFORMER CORP. #A-3850
PRIMARY 4-14 kOHM 40 MA
TURNS RATIO TEST TEST VOLTS RATIO
APPLIED 60 HZ AC TO
BROWN AND BLUE WIRES,
(ENTIRE PRIMARY) 12.820
MEASURED SEC. 1-2 0.100 128.200
1-3 0.150 85.467
1-4 0.200 64.100
1-5 0.337 38.042
1-6 0.700 18.314
OUTPUT TAP
CALCULATOR
DESIRED
IMPEDENCE
REQUIRED
RATIO
EQUIVALENT
TEST VOLTS
SPEC LOAD FOR 171A 5350.000 25.86 0.496
VOICE COIL Z SPEC 8.000
1-6 MINUS 1-4 IS CLOSE TEST VOLTS ACT. RATIO ACTUAL PRI. Z
CONNECT SPKR TO 4-6 0.500 25.640 5259 OHMS
Replacement 2
nd AF Transformer, Installed
Restoration of the #9575 .3F, Single Bypass Capacitor
I planned to re-use the original wires;
I first removed the speaker post so that I wouldnt have to unsolder one of the #9575 wires from the solder lug
I then unsoldered the other wire of the #9575 from pin 2 of the UX-171A.
I carefully removed the #9575 from the chassis
I placed the #9575 on a piece of paper and made pencil tracings to show exactly where each one of the two wires
emanated from the part. The wires are distinguishable by
the fact that one has a solder lug attached and one does
not. During tracing I let the wires dangle over the edge
of the table, as they were quite stiff. I made note of their
stiffness orientation relative to the unit, so that I
could put them back in that same orientation when I soldered
them to the new capacitor assembly.
I placed the #9575 unit (a.k.a. #14902) in a pie pan and heated
it in the oven, set to 300o, for just a few minutes. The pitch
became very liquid and runny, and the old capacitor slipped right
out easily, along with one of two paper insulators. Some of the
liquid pitch pooled under the unit and left some stain on the
case. I should have elevated the unit using small sticks or
something, so that the pitch would not run out onto its case.
Mineral spirits cleaned up the residue, though.
The rebuilt #9575 (#14902) consists of two new 0.15uF 400 volt
polyester capacitors connected in parallel and soldered to the
original wires. I made an assembly as sketched below, for
insertion into the case of the old #9575. I used the wire location
and orientation templates that I made earlier to position the
old wires and tape the cardboard sandwich shut, such that the
old wires were held reasonably secure.
Monday, December 17, 2007- I completed restoring the #9575
speaker DC block capacitor and I re-installed it, the speaker
post, and the wire with the solder lug attached. I will wait
until later to re-solder the other wire to the UX-171A plate
terminal, pin 2.
Saturday, Dec.29, 2007-
I found the #8 fastener hardwares that I needed at my moms house last week, during my visit there.
I installed new 68k and 12k 1 watt resistors on the power supply terminal board.
0.15 F
0.15 F
BLACK
ELECTRICAL
TAPE
BLACK
ELECTRICAL
TAPE
ORIGINAL WIRES
FROM PART #14902
CORRUGATED CARDBOARD
SANDWICH (TOP PIECE NOT
SHOWN)
REBUILT #14902 SINGLE BYPASS CONDENSER
WRAP SINGLE LAYER OF
ELECTRICAL TAPE AROUND
THE CAPACITORS
Monday, Dec.31, 2007- I re-wired and tested the power supply
unit today, per the original schematic diagram in the Service
Manual.
I wrapped the audio choke in cardboard and placed it at the bottom of the empty compartment. I brought the two wires
upwards to be connected to the terminal board later.
I partially pre-wired the three 1.5uF capacitors, wrapped them in cardboard, and place them on top of the audio choke.
I wired the two .5 uF capacitors to the underside of the terminal board. One lead of one of the .5 uF is attached
to a ground lug.
I installed the terminal board and then soldered all remaining wires to it, in accordance with the schematics.
I re-checked all resistances as OK, including the filter chokes.
I attached a temporary AC line cord so that I could test the power supply unit without the ON-OFF switch being
present.
I cleaned the pins of the UX-480 tube and its socket on the power supply unit, and I installed the UX-480.
I applied AC power at 12:56 pm today and measured +411 volts DC at the 2
nd AF B+ post on the terminal board. Given that
there is no load, this is a PASS!
The filament voltages measured as follows. There is some load
because the center-tapped filament resistors are in the
circuits.
RF / 1st AF spec. 1.5V meas. 1.75V PASS
Detector spec. 2.5V meas. 2.70V PASS
2nd AF spec. 5.0V meas. 5.06V PASS
The measured filament voltages are slightly higher than
specified probably because the AC line voltage measured 120 volts
instead of the 110 Volts that the model 40 set was designed for.
I will address this important matter later.
I installed the new ON-OFF switch into the cabinet, and a new old-style power cord. I made a cardboard cable clamp
to replace the missing clamp.
I installed the power supply unit into the cabinet and attached it with a complete set of fasteners.
I completed connecting the AC power cord and the new ON-OFF switch to the power supply unit.
Chapter 3, January 2008, 1st Light
January 5, 2008- I performed a filament DC resistance check for
all of the tubes, including the new ones that I bought many
years earlier, when they were much cheaper than they are today.
All tested OK.
January 12, 2008-
I installed or re-attached all wires pertaining to my replacement 2
nd AF interstage transformer.
I re-attached the remaining wire of the #14902 condenser to pin 2 of the UX-171A socket.
I installed a new 2.2M watt grid leak resistor on the
detector audio board. The original 2M cartridge-type
resistor was missing when I bought the set, as I stated
earlier.
Restoration of the #9928 Double Bypass Condenser
I unsoldered the wires, and then I removed the #9928 (a.k.a.
#15158) capacitor unit from the set. Since the wires maintain
their stiffness, you can re-use them correctly by matching them
to their shapes in the sketch below (the colors may not be the
same as in the sketch).
I fitted the new polyester capacitors into the old condenser
housing according to the following layout, which is viewed from
the bottom of the housing;
I made a cardboard sheet with rectangular cutouts for the parts,
to hold them in position, and the sandwich concept to attach
and secure the original wires in their original locations. I
soldered the ground wire to the inside of the #9928 housing.
January 15, 2008-
Tonight I completed the rebuild of the #9928 Double Bypass
Condenser, as described earlier, and re-installed it. I cleaned
all of the tube socket terminals using Q-tips soaked in contact
cleaner. I prepared and re-soldered one of the harness wires
to pin 2 (plate) of the UX-171A socket. This completed the initial
electrical restoration. Here is a summary of chassis parts
replaced;
Single Bypass Condenser(a.k.a. Speaker DC block )
Double Bypass Condenser
2nd AF interstage transformer
Grid Leak resistor [Chassis parts not replaced but that I should have replaced,
as I will discuss later;
Phone Condenser, .002F
Detector grid condenser, 250F]
Power unit parts replaced were as follows;
12k resistor
68k resistor
1.5F filter capacitors, non-polarized
.5F capacitors
Audio Choke [Power unit parts not replaced but that I should have replaced,
as I will discuss later;
Part #13538, tapped 625/2200wire-wound resistor on the terminal board.
January 15, 2008-
I used the multimeter to perform final wiring continuity checks
of the entire chassis, per the schematic. All OK. Then I
lubricated the tuning capacitor shafts,
installed the chassis into the cabinet,
attached the Antenna/Ground bracket to the cabinet,
installed the harness board to the power supply terminal board,
installed the power supply cover, and
installed all of the tubes
Line Rheostat Assembly
I stated earlier that this set is designed to operate from 110
Volt AC line, but modern line voltage is typically higher. Here
at our house the line voltage is usually 120 volts. I dont want
to shorten tube filament life by having too high voltage, so
I found (in my junkbox!) a 50 power rheostat, rated at 50 watts,
to place in series with the sets AC line. To pre-set the
rheostat, I needed to estimate the power consumption of the radio
set when its AC line voltage is 110 Volts. I used the Atwater
Kent service manual voltage tables, my data from my power
transformer test (see Chapter 1), measured resistances, and
specified resistances, to make an estimate of 37.2 watts for
a Model 40 set.
AK POWER TRANSFORMER TEST USING THE 12V TRANSFORMER FROM YARD LIGHTS AS STEP DOWN FOR AK PRIMARY
14 DEC. 2007 FILTER INPUT
WALL VOLTAGE 110 VOLTS AC spec WINDING PRED 1.1
TEST VOLTAGE PRIMARY 12.7 VOLTS AC DC RES LOAD IR OF XFMR OUTPUT
RATIO TEST/WALL 0.115 TEST/WALL CENTER TAP OHMS AMPS DROP VOLTS
MEASURED SECONDARIES TEST VAC RATIO VAC TEST RESULT RMS PEAK MEAS. SPEC LOADED SPEC
H V 63.10 4.97 546.54 PASS 273.27 386.46 240 0.044 10.632 288.90
RECTIFIER FIL 0.61 0.05 5.31 PASS 0.35 2 0.7 4.61 5.0
RF/1ST AF FIL 0.18 0.01 1.59 PASS 0.05 4 0.2 1.39 1.5
DETECTOR FIL 0.28 0.02 2.45 PASS 0.1 1.75 0.175 2.28 2.5
2ND AF FIL 0.53 0.04 4.61 PASS 0.2 0.25 0.05 4.56 5.0
The spreadsheet indicated that the rheostat should be set to
about 30, or alternatively, adjust the rheostat to produce 110
volts across a 40 watt incandescent light bulb dummy load.
DO NOT use any other type of 40 watt lamp, as it may not actually
present a 40 watt load (i.e., the pig-tail tree-hugger type
bulbs).
Sunday, January 20, 2008, 2:50 pm- I did the following;
attached a 4K-to-3.2 audio output transformer, with speaker, to the speaker terminals inside the set
attached a 4 foot long wire to the antenna post
measured the AC line voltage at 123.4 volts (higher than usual),
plugged the set into the rheostat assembly, and
Turned the set ON, for the first time since I bought it
The set came to life. I could hear KNX radio station. DC voltage
checks were all close to those listed in the Atwater Kent Service
Manual;
Spec. Measured
RF 160 volts Close
Detector 44 volts 40 volts
1st AF 155 volts 160 volts
2nd AF 180 volts Close
The volume control had no effect until I seated the lid onto
the set. KNX station RF was getting into set past the volume
NOT SURE HOW TO ACCOUNT FOR THE UX280 PLATE RESISTANCE VS. CAPACITOR INPUT FILTER
IR DROP DC SPEC DISS TUBES
MA VOLTS VOLTS compare POWER B+POWER
CHOKE 1 675 OHMS 29.90 259.00 1.32
CHOKE 2 675 OHMS 29.90 229.09 1.32
AUDIO CHOKE/2NDAF 550 OHMS 19 10.45 176.84 180 0.20 3.36
RF PLATES 3000 OHMS 17.5 52.50 162.53 160 0.92 2.84
1ST AF 12500 OHMS 5 62.50 152.53 155 0.31 0.76
DET 65000 OHMS 2.8 182.00 47.09 44 0.51 0.13
44.3 4.59 4.59
2ND AF BIAS RESISTOR 2200 OHMS -41.80 GRID 2AF -45 0.79 WATTS
RF 1ST AF BIAS 625 OHMS -14.06 GRID RF -13 0.07 WATTS
12.55
load powers
POWER TRANSFORMER
B+ 0.47 FILAMENTS 10.0
1.40 6.0
0.80 4.4
0.31 1.3
0.01 TOTAL FILAMENTS 21.6 WATTS
TOTAL TRANS NI PRI 2.99 WATTS GRAND NI TRAN PRI 37.2 WATTS
PRI. DC RES. MEAS. 8 OHMS
PRI. CURRENT 0.34 AMPS
IR DROP PRI. 2.70 VOLTS
POWER LOSS PRI. 0.91 WATTS
10V drop from 120vac 29.60 OHMS
3.38 WATTS
control. It is a 50kW station less than two miles away. Hum level
was higher than I expected [solved later].
Sunday, January 20, 2008, 8:00 pm
Over several hours I observed erratic performance and also the
set was not picking up other stations besides KNX.
I cleaned the pins of the UY-227 detector and the 1st AF UX-226,
using finest grit Testors modeler sandpaper, followed by paper
towel wipes with contact cleaner. This made a BIG difference.
Now I could tune in all local stations as well as KFMB in San
Diego, 110 miles away (50kW at night).
Next Several Days, to January 25, 2008
I observed occasional hum, or motorboating, that would
sometimes stop by tapping UX-226 1st AF or the UY-227 detector.
I installed a Curtis Industries model F2700CA03 RFI filter on
the input side of my AC line rheostat.
Chapter 4, 2008-2011, Re-Work to Fix the Remaining Issues
March 30, 2008- According to my original notes, I finally began
to suspect that the intermittent hums, pops, and motorboating
might be due to one or both of the two original capacitors that
I did not replace; the .002F phone condenser and the 250F detector grid condenser. I also noted that the volume control
was very noisy and erratic.
March 31, 2008- I noted that the set is much less sensitive than
it was when I first got it working.
April 6, 2008- I decided to replace the 2200/625 tapped
wire-wound resistor that is on the power supply terminal board,
because it now tests as intermittantly open on the 625side.
April 19, 2008- I ordered metal oxide 2200 2-watt and 680 1-watt
resistors, and formed their leads as shown below, so that the
original wires on the terminal board remained undisturbed;
Resistor Layout to Replace the AK Part #13538
To provide additional clearance for the new resistors, I placed
one #8 brass flat washer on each of the 11 outer terminal studs.
I placed two flat washers on each of the two center post studs
so that the harness board would be high enough to not press on
the new resistors.
Stick Photo Here
I replaced the .002F phone condenser with a new Orange Drop part.
Stick Photo Here
I replaced the 250F detector grid condenser with a new 250uuF silver-mica part. For appearance, I located the new part
underneath the old part. The old part is no longer in the circuit.
These parts are on the top side of the chassis and attached to
a terminal of the 3rd (from left) tuning condenser.
Stick Photo Here
April 20, 2008
Now the set is working much better. Sensitivity is very good
to excellent. No more motorboating. Tuning range appears to
be 570 kHz to 1650 kHz. AC hum is acceptably low. The set pulls
in many DX stations at night. The set is now quite useable, but
the volume control is annoying due to several scratchy spots.
As long as I keep the set on my favorite station I can live with
it, for now.
2200
680
was
is
STATION LOG 2008
Date and notes not recorded- I finally found a model E-3 matching
speaker in very good condition, also at a swap meet, for $15.
The cable was only partial, so I extended it using several feet
of 4-conductor telephone cable from Radio Shack, with the 4
conductors employed pair-wise. The speaker seems to work fine.
There is some evidence of restoration (newer rear grill cloth,
and minor marks where the front and rear sections woud have been
pried apart), but I do not know the history of it and I have
not attempted to disassemble it.
----------------------------------------------------------
July 26, 2009(yes, over 1 year later)
I disassembled and attempted to clean and restore the volume
control. I was only partially successful. There was some
reduction of the noisy behavior, but still not satisfying, and
it didnt last. My cleaning method may have been crummy. [I tried
again, as described later]
----------------------------------------------------------
July 6, 2011 (yes, another 2 years go by)
I was looking for something else in my junk boxes today, and
discovered a volume control unit for the Model 40! I had
completely forgotten that I bought it at some swap meet back
in the 1990s, maybe even the same swap meet as the set itself.
It was dirty, but complete. I measured the winding resistance
as 425, just right. I brought it out of the bone yard, but
postponed effort due to other priorities.
ATWATER KENT
MODEL 40
DIAL KHZ STATION XMTR LOCATION STATE FORMAT DAY NIGHT NETWORK/SHOWS
87 570 KLAC LOS ANGELES CA SPORTS 5KW 5KW
78 600 KOGO SAN DIEGO CA TALK 5KW 5KW ROGER HEDGECOCK
67 640 KFI LA MIRADA CA TALK 50KW 50KW TIM CONWAY, JR
63 660 KTNN WINDOW ROCK AZ NAVAHO 50KW 50KW CNN
61 670 KIRN SIMI VALLEY CA PERSIAN 5KW 3KW
58 690 XETRA TIJUANA, MEXICO MEX MEXICAN 77KW 50KW
53 710 KSPN LOS ANGELES CA SPORTS 50KW 10KW LAKERS
52 720 KDWN LAS VEGAS NV TALK 50KW 50KW
48 740 KBRT AVALON CA CHRISTIAN 10KW 113W
48 740 KCBS SAN FRANCISCO CA NEWS 50KW 50KW CBS
46 760 KFMB SAN DIEGO CA TALK 5KW 50KW ABC/mark levin/o'reilly
44 770 KKOB ALBUQUERQUE NM TALK 50KW 50KW bill cunningham
42 790 KABC LOS ANGELES CA TALK 5KW 5KW ABC
40 810 KGO SAN FRANCISCO CA TALK 50KW 50KW
37 830 KLAA NORCO/CORONA CA TALK 50KW 20KW
36 840 KXNT LAS VEGAS NV TALK 50KW 25KW bill cunningham
35 850 KOA DENVER CO TALK 50KW 50KW bill cunningham
34 870 KRLA GLENDALE CA TALK 50KW 3KW WSJ THIS MORNING
28 930 KHJ LOS ANGELES CA MEXICAN 5KW 5KW
25 980 KFWB LOS ANGELES CA NEWS 5KW 5KW
22 1020 KTNQ LOS ANGELES CA MEXICAN 50KW 50KW
20 1070 KNX TORRANCE CA NEWS 50KW 50KW NEWS/CBS
17 1150 KTLK LA PUENTE CA TALK 50KW 44KW PHIL HENDRIE
14 1260 KGIL PANORAMA CITY CA TALK 20KW 7.5KW OLDIES (WEEKENDS)
13 1280 KFRN WILMINGTON CA CHRISTIAN 1KW 1KW
9 1390 KLTX PARAMOUNT CA MEXICAN 5KW 3.6KW
5 1650 KFOX EAST OF CULVER CITY CA KOREAN 10KW 490W
----------------------------------------------------------
Monday, November 14, 2011
Unlike my prior cleaning attempt, I completely disassembled this
spare volume control for cleaning, taking careful note of the
orientation of the resistance unit. Its windings have a
low-density region and a high density region. The low density
portion is for low-end of the volume setting range, so you want
to be sure to re-install this part with correct orientation.
I did these steps;
Used paint thinner and paper towel (should have used T-shirt cloth, perhaps) to clean the housing and the resistance
unit.
Used Revere Ware Copper Cleaner to restore the wiper assembly and the control shaft surfaces.
Used lots of warm water rinse to make sure all of the copper cleaner residue was removed.
Used a jewelers loupe to inspect the resistance unit and the wiper. Some paper towel fibers were lodged in the
winding. I used T-shirt cloth to brush them away.
Made a knob pointer alignment template to aid re-assembly.
Reassembled the unit and tested it with my Fluke multimeter as I slowly rotated the control. The resistance changed
smoothly over the entire range, with no obvious skips.
----------------------------------------------------------
Tuesday, January 27, 2015
Yesterday I removed the bad volume control unit and replaced
it with the one I restored in November, 2011 (see previous note
above).
I also removed the defective 2nd interstage audio transformer
from its case, by heating it to 300 deg. to liquefy the pitch.
I unsoldered the blue wire temporarily so that I could maneuver
the AES unit into the old transformer case. The AES interstage
transformer just fit inside the case. I took a picture of the
transformer before removing the old core;
The restored volume control works great. There are no more loud
pops or scratches when changing volume.
Today I logged the Mexican station XESURF at 540 kHz. This
verifies the tuning range of the set as 540 kHz to above 1650
kHz. I also heard at least two stations at high end of the band
that I had not logged before, but there is significant
adjacent-channel-interference at high end of the band. As
expected, TRF sets do not have very good selectivity above about
1000 kHz. I updated the radio log table.
Restored AK40, February 2015
*Change since 2008
----------------------------------------------------------
See the advertisement on next page. According to
www.dollartimes.com, $77.00 in 1929 had the same buying power
as $986.95 in 2011. The speaker was $20, or $256.35 in 2011.
Note that the seven tubes were not included.
Another site, http://www.1soft.com/todaysdollars, says $819.82
I paid about $900 for my Toshiba laptop last year.
THE END
ATWATER KENT UPDATE 1/27/2015
MODEL 40
DIAL KHZ STATION XMTR LOCATION STATE FORMAT DAY NIGHT NOTES
100 540 XESURF MEXICO MEX MEXICAN 25KW 100W
87 570 KLAC LOS ANGELES CA SPORTS 5KW 5KW DODGERS GAMES
78 600 KOGO SAN DIEGO CA TALK 5KW 5KW bill cunningham*
67 640 KFI LA MIRADA CA TALK 50KW 50KW TIM CONWAY, JR
63 660 KTNN WINDOW ROCK AZ NAVAHO 50KW 50KW CNN
61 670 KIRN SIMI VALLEY CA PERSIAN 5KW 3KW
58 690 XETRA TIJUANA, MEXICO MEX MEXICAN 77KW 50KW
53 710 KSPN LOS ANGELES CA SPORTS 50KW 10KW LAKERS GAMES
52 720 KDWN LAS VEGAS NV TALK 50KW 50KW
48 740 KBRT AVALON CA CHRISTIAN 10KW 113W
48 740 KCBS SAN FRANCISCO CA NEWS 50KW 50KW CBS
46 760 KFMB SAN DIEGO CA TALK 5KW 50KW ROGER HEDGECOCK*
44 770 KKOB ALBUQUERQUE NM TALK 50KW 50KW bill cunningham
42 790 KABC LOS ANGELES CA TALK 5KW 5KW DOUG MCINTYRE
40 810 KGO SAN FRANCISCO CA TALK 50KW 50KW
37 830 KLAA NORCO/CORONA CA SPORTS* 50KW 20KW
36 840 KXNT LAS VEGAS NV TALK 50KW 25KW bill cunningham
35 850 KOA DENVER CO TALK 50KW 50KW bill cunningham
34 870 KRLA GLENDALE CA TALK 50KW 3KW WSJ THIS MORNING
28 930 KHJ LOS ANGELES CA CATHOLIC* 5KW 5KW IMMACULATEHEART*
25 980 KFWB LOS ANGELES CA SPORTS* 5KW 5KW CLIPPERS GAMES*
22 1020 KTNQ LOS ANGELES CA MEXICAN 50KW 50KW
20 1070 KNX TORRANCE CA NEWS 50KW 50KW NEWS/CBS
17 1150 KEIB* LA PUENTE CA TALK 50KW 44KW RUSH, HANNITY
14 1260 KMZT* PANORAMA CITY CA MUSIC 20KW 7.5KW CLASSICAL
13 1280 KFRN WILMINGTON CA CHRISTIAN 1KW 1KW
9 1390 KLTX PARAMOUNT CA MEXICAN 5KW 3.6KW
7 1580? KBLA LOS ANGELES CA MEXICAN 50KW
6 1620? tbs REDONDO BEACH CA HIGHWAY 10W 10W CITY LOW POWER
5 1650 KFOX EAST OF CULVER CITY CA KOREAN 10KW 490W
APPENDIX A - DISASSEMBLY PROCEDURE
During this restoration effort I developed the following
procedure for safely disassembling the set;
1. Remove all tubes and carefully store them away.
2A. Remove the tuning vernier knob.
2B. Remove the main tuning knob.
3. Remove the cover of the power supply unit.
4. Remove the hex nuts and lock washers that attach the cable harness
board to the power supply terminal board, and lift the cable board
off of the terminal studs.
5. Unfasten the antenna/ground posts bracket from the rear of the
cabinet.
6. Rest the set face down on cushioned 2x4 wooden blocks placed on
each side, such that the tuning shaft is not touching the table top.
I wrapped my blocks with old dishtowel cloths.
7. Remove the fasteners that hold the chassis to the front panel
brackets.
8. Carefully lift the chassis so that the tuning shaft and the volume
control clear the front panel, and then remove the chassis while making
sure the various cables dont fall or get snagged. The power supply
unit, AC wiring, and the ON-OFF switch are to remain in place inside
the cabinet.
9. Set the cabinet back on its feet, on top of the wood blocks.
10. Unscrew the fastening nut of the ON-OFF switch and rest the switch
on floor of cabinet, with wires still attached.
11. Remove all fasteners that attach the power supply unit and the
AC power wiring clamp to the cabinet, and lift the unit out of the
cabinet along with the ON-OFF switch and their associated wiring.
12. Remove the cabinet feet if you plan to restore the cabinet.
Appendix B Photo Re-Touched
February 10, 2015- I wanted to know how my set would look if
I could repair the paint scratches. I used MS Paint to cover
up the most severe scratches.
Touched Up Photo Shows Appearance if Scratches Repaired
