T3 190, 193 Series
Detrola; Detroit (MI)
- Country
- United States of America (USA)
- Manufacturer / Brand
- Detrola; Detroit (MI)
- Year
- 1938
- Category
- Broadcast Receiver - or past WW2 Tuner
- Radiomuseum.org ID
- 37406
Click on the schematic thumbnail to request the schematic as a free document.
- Number of Tubes
- 8
- Main principle
- Superheterodyne (common); ZF/IF 456 kHz; 2 AF stage(s)
- Tuned circuits
- 7 AM circuit(s)
- Wave bands
- Broadcast, Short Wave(s) and Police.
- Power type and voltage
- Alternating Current supply (AC) / 115 Volt
- Loudspeaker
- Electro Magnetic Dynamic LS (moving-coil with field excitation coil)
- Material
- Wooden case
- from Radiomuseum.org
- Model: T3 190, 193 Series - Detrola; Detroit MI
- Shape
- Tablemodel with Push Buttons.
- Notes
-
BC 540-1600 kHz), TROP (1650-5400 kHz) and SW (5.4-16.0 MHz) bands.
John F. Rider schematic Detrola Page 9-1 shows Models 175 Series (T1, C1), 190, 193 Series (T2, T3), and 195 Series (C4). The alignment procedure is the same as the 185 Series.
- External source of data
- Ernst Erb
- Source of data
- Machine Age to Jet Age III
- Circuit diagram reference
- Rider's Perpetual, Volume 9 = 1938 and before
- Other Models
-
Here you find 334 models, 195 with images and 291 with schematics for wireless sets etc. In French: TSF for Télégraphie sans fil.
All listed radios etc. from Detrola; Detroit (MI)
Forum contributions about this model: Detrola; Detroit MI: T3 190, 193 Series
Threads: 1 | Posts: 13
Jeffrey D Angus wrote:
Some of the test equipment I'm using on this train wreck.
HP 3325A synthesized signal generator. (Makes a very nice sweeper.)
Tektronix 422 dual channel scope. (Run of the mill, but nice.)
Motorola R-2018 Service Monitor. (Using it as a spectrum analyzer.)
Using the sweeper at 436 KHz to 476 KHz I get about a 15 KHz wide
peak at 456KHz through the IF transformers. I have to scope connected
to the top of the volume control so I can set the sweep rate at
0.05 seconds per sweep.
Using the sweep generator set at both 1500 KHz and 600 KHz, all of
the trimmer capacitors (and main tuning caps) appear to be working
properly as far at physically and electrically.
But... The radio is deaf as a post. I can only hear a couple of the
local flame thrower stations and only just barely above the noise.
Using the spectrum analyzer with a short wire pickup probe inside
either of the IF transformer cans, I'm seeing a pass band of noise
that is 30 dB above the noise floor. This is apparently enough to
fully close the eye tube with the detected noise and subsequent
AVC voltage.
Now, I've pulled the grid cap of of the 6D6 IF amplifier and the
wide band high level noise is still there in the 1st IF can.
Grounding the 6A7 mixer input grid cap with a .01 uF capacitor
eliminates the noise. (along with everything else)
This radio is the one with the motorized tuning. The push buttons
go to settable commutator stops to position the main tuning cap.
They do not go to additional antenna and local oscillator coils.
As yet another attempt in solving this problem, I took a 7 pin tube
base and an octal socket and made a "6A8 for 6A7" tube adaptor. It
actually works, shifted the receive frequency down a little bit, but
is still deaf as a post.
The basic B+ as measured off of the rectifier (and supplying the
plates of various tubes is about 220 VDC.
At this stage, I'm about ready to gut the mixer and IF section and
install a 6BE6 and 6AU6 with a couple of K-tran IF transformers and
call it day.
(Yes, I've been fighting this one for 3 weeks now.)
Jeff
Electrically, it is identical to a Detrola 190.
6A7, 6D6, 75, 76, 42, 42, 6G5 and 80 rectifier.
http://www.nostalgiaair.org/PagesByModel/919/M0003919.pdf
The problem:
Lots of inter station white noise. Like what you'd expect from
a "hot" receiver, except... it's deaf as a post only able to
hear the local flamethrower stations.
I've checked the B+, and the AVC voltages. They are as one would
expect. But occasionally, the radio will go up and back down in
volume. Very annoying.
Some of the test equipment I'm using on this train wreck.
HP 3325A synthesized signal generator. (Makes a very nice sweeper.)
Tektronix 422 dual channel scope. (Run of the mill, but nice.)
Motorola R-2018 Service Monitor. (Using it as a spectrum analyzer.)
Using the sweeper at 436 KHz to 476 KHz I get about a 15 KHz wide
peak at 456KHz through the IF transformers. I have to scope connected
to the top of the volume control so I can set the sweep rate at
0.05 seconds per sweep.
Using the sweep generator set at both 1500 KHz and 600 KHz, all of
the trimmer capacitors (and main tuning caps) appear to be working
properly as far at physically and electrically.
But... The radio is deaf as a post. I can only hear a couple of the
local flame thrower stations and only just barely above the noise.
Using the spectrum analyzer with a short wire pickup probe inside
either of the IF transformer cans, I'm seeing a pass band of noise
that is 30 dB above the noise floor. This is apparently enough to
fully close the eye tube with the detected noise and subsequent
AVC voltage.
Now, I've pulled the grid cap of of the 6D6 IF amplifier and the
wide band high level noise is still there in the 1st IF can.
Grounding the 6A7 mixer input grid cap with a .01 uF capacitor
eliminates the noise. (along with everything else)
This radio is the one with the motorized tuning. The push buttons
go to settable commutator stops to position the main tuning cap.
They do not go to additional antenna and local oscillator coils.
As yet another attempt in solving this problem, I took a 7 pin tube
base and an octal socket and made a "6A8 for 6A7" tube adaptor. It
actually works, shifted the receive frequency down a little bit, but
is still deaf as a post.
The basic B+ as measured off of the rectifier (and supplying the
plates of various tubes is about 220 VDC.
At this stage, I'm about ready to gut the mixer and IF section and
install a 6BE6 and 6AU6 with a couple of K-tran IF transformers and
call it day.
(Yes, I've been fighting this one for 3 weeks now.)
Jeff
Jeffrey Angus, 29.Sep.08