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FM-DW converter and AM Saver modules for your vintage radios

Tune with the dial, listen with the radio's original amplifier !
Welcome to the FM-DW 2.0 and AM Saver add-on page !

        

Functional improvements:

- Optional AM Saver module (sold separately).
- Dual color LED for easy setup.
- Added 50µs / 75µs de-emphasis choice in setup.
- Added optional stereo output.
- Added optional Stereo Noise Control.
- Added live reset in addition to the cold reset.
- Improved firmware and tuning.
PCB improvements:

- Added silkscreens for easy installation.
- Round corners and thiner pcb.
- Flat push-button replaced by a better model.
- Added a pad to connect a separate push-button.
- Enlarged Antenna and Tuning Capacitor pads.
- Added a +5V 50mA regulated output for small add-on.
- URL of this page on bottom layer of FM-DW module.


FM-DW 2.0 main specs:

- FM 87.5 - 108 MHz using radio's dial for tuning. Choose where the FM starts and ends on your dial.
- Can be AC powered by tube heaters circuit (parallel heaters only).
- Can be DC powered (4V to 16V - minimum 6V if using the +5V output).
- No additional controls required, no external mods !
- Compact and easy to install: 3 cm x 3.6 cm, three grounded holes, grounded bottom layer.
- Added de-emphasis choice in setup.
- Added optional stereo output in setup.
- On-board +5V DC regulated output (50mA max) for accessory (Bluetooth or other)
- 120 ohms FM antenna recommended. A 3ft wire is sufficient in most cases.


AM-Saver main specs:

- Sits over the FM-DW, uses its main power source.
- Preserves the AM bands using a single switch to commute between AM and FM.
- Can disable the AM frequency changer in FM mode if required.


Important notes:

The FM-DW and AM Saver modules require an AM tuning capacitor, and will not work with variable inductors.
If using the AM Saver, ensure that the tuning capacitor be not originally connected to high voltage otherwise the FM-DW module will be damaged by any residual charge when switching.
DAB/DAB+ radios can only be heard using a DAB/DAB+ to FM transmitter, which avoids altering the radio to insert additional controls and a LCD screen.

The AM bands can be preserved using the optional AM Saver "piggy-back" module or a custom switching circuit.

Installing FM-DW 2.0 alone
Refer to the next tab if AM bands are required.


The FM-DW module uses electrostatic sensitive devices: the installation and setup must be performed by a person with sufficient electronics background (especially in restoring vintage tube and transistor radios) to avoid damages, otherwise you are installing and using the FM-DW module (and eventually the AM Saver module) at your own risks.


Ensure that your radio is accordingly restored and that its amplifier works correctly.
Keep the radio unpluged from the mains during the whole installation procedure.
The mains switch of your radio must be clean and not produce excessive arcing.
If required, a suppressor capacitor may be added in parallel to it.


As we will no longer use the AM bands, the IF section is no longer required. Therefore, you may disconnect the plate and screen grid circuits of the IF tubes, and remove those IF tubes if their heaters are connected in parallel. If the high voltage increases too much after disabling the IF section, the DC filter should be adjusted with a higher resistor (or a resistor added in series with the speaker field coil).


Before all, ground the FM-DW module to the chassis (very important with AC/DC sets).
Its three grounded holes as well as its fully grounded bottom side allow a solid attachment.


The tuning capacitor's condition is critical: it must have no contact faults with the rotary part, no excessive dust between plates, and obviously no shorts. Such faults will distort the capacitance measurements, resulting in improper setup and/or unstable (when not impossible) tuning. The tuning capacitor's body must be grounded. In portable DC radios with a chassis connected to the +, ensure that the tuning capacitor's body be insulated from the chassis.

The tuning capacitor must be connected to the FM-DW module pad designated by a variable capacitor symbol. Ensure that nothing else is connected to the tuning capacitor (parallel capacitive trimmers can be left and set to their maximum). For short wave radios using a low capacitance tuning capacitor, it is recommended to group its sections to maximize its capacitance. In all cases, it is possible to add a fixed capacitor in parallel so that the maximal capacitance is around 1000pF. Also, ensure that the minimum capacitance is around 40pF or higher.


The FM-DW AC/DC in pad powers the module with alternative current (4V to 10V) or direct current (see below).
A heater winding delivering 4V to 10V AC can be directly connected to the FM-DW module if it has one grounded side and no center tap (Fig. 1). A voltage doubler is required if this heater winding outputs 2.5V to 4V AC (Fig. 2).
If the heater winding has a grounded center tap and outputs 2.5V to 4V AC, a voltage doubler is required (Fig. 3). If it outputs 6.3V AC, use either half with a voltage doubler as shown in Fig. 2.
Radios with heaters connected in series must use a separate DC power supply delivering sufficient current:
- The radio section of the FM-DW module draws under 50mA,
- When used, the on-board 5V regulated power supply draws up to 50mA,
- When using the on-board +5V regulated output, the minimum DC voltage is 6V (4V otherwise).


Fig. 1: powering the FM-DW module using a grounded heater winding of 4Vac to 10Vac.


Fig. 2: powering the FM-DW module using a grounded heater winding (2.5V to 4V AC) with no center tap.


Fig. 3: powering the FM-DW module using a grounded center-tapped heater winding (2.5V to 4V AC).

The FM-DW Antenna pad connects differently depending on your configuration.
With AC/DC sets, a 1 Megohm resistor should be added between the FM-DW antenna pad and the chassis.
Remove anything previously connected to the radio's antenna plug and connect it to the antenna pad of the FM-DW module.
A 120 ohms antenna is recommended (a 3ft wire should be sufficient in moste cases).


The FM-DW L OUT pad must be used with mono receivers. Radios equiped with a stereophonic amplifer will use it as the Left channel source. Connect the L OUT pad to the LF amplifier input after having disconnected the detector circuit. With AC/DC radios, a 0.01µF/630V capacitor may be inserted before the amplifier input unless already present by design. Its value is not critical. A shielded wire should be used except for short lenghts. As a reminder, only one side of the shield must be grounded.


The FM-DW R OUT pad is only required for radios equiped with a stereophonic amplifier. As with the L OUT pad, the R OUT pad connects to the Right channel input of the LF amplifier (after having verified that the detector circuit is no longer connected to it).


The FM-DW Setup pad allows connecting an additional Setup push-button, which other end must be grounded.


D o u b l e     C h e c k     y o u r     w i r i n g
     before configuring the FM-DW module.

Installing FM-DW 2.0 with AM-Saver
Refer to the previous tab if AM bands are not required.

    


The FM-DW and AM-Saver modules use electrostatic sensitive devices: the installation and setup must be performed by a person with sufficient electronics background (especially restoring vintage tube and transistor radios) to avoid damages, otherwise you are installing and using the FM-DW module (and eventually the AM Saver module) at your own risks.

Ensure that your radio is accordingly restored and that its amplifier works correctly.
Keep the radio unpluged from the mains during the whole installation procedure.
The mains switch of your radio must be clean and not produce excessive arcing.
If required, a suppressor capacitor may be added in parallel to it.


Before all, ground the The FM-DW module to the chassis (very important with AC/DC sets).
Its three grounded holes as well as its fully grounded bottom side allow a solid attachment.


The tuning capacitor's condition is critical: it must have no contact faults with the rotary part, no excessive dust between plates, and obviously no shorts. Such faults will distort the capacitance measurements, resulting in improper setup and/or unstable (when not impossible) tuning. The tuning capacitor's body must be grounded. Its fixed plates must not be connected to any high voltage by design, otherwise the FM-DW module might be permanently damaged by residual charges when switching between AM and FM.

In DC radios having a chassis connected to the +, ensure that the tuning capacitor's body be insulated from the chassis. The tuning capacitor will be connected to the AM Saver module later.


The FM-DW AC/DC in pad powers the module with alternative current (4V to 10V) or direct current (see below).
A heater winding delivering 4V to 10V AC can be directly connected to the FM-DW module if it has one grounded side and no center tap (Fig. 1). A voltage doubler is required if this heater winding outputs 2.5V to 4V AC (Fig. 2).
If the heater winding has a grounded center tap and outputs 2.5V to 4V AC, a voltage doubler is required (Fig. 3). If it outputs 6.3V AC, use either half with a voltage doubler as shown in Fig. 2.
Radios with heaters connected in series must use a separate DC power supply delivering sufficient current:
- The radio section of the FM-DW module draws under 50mA,
- When used, the on-board 5V regulated power supply draws up to 50mA,
- The AM Saver add-on module draws around 100mA (it is turned off in FM mode).
When using the on-board +5V regulated output, the minimum DC voltage is 6V (4V otherwise).


Fig. 1: powering the FM-DW module using a grounded heater winding of 4Vac to 10Vac.


Fig. 2: powering the FM-DW module using a grounded heater winding (2.5V to 4V AC) with no center tap.


Fig. 3: powering the FM-DW module using a grounded center-tapped heater winding (2.5V to 4V AC).

The FM-DW Antenna pad connects differently depending on your configuration.
With AC/DC sets, a 1 Megohm resistor should be added between the FM-DW antenna pad and the chassis.
Connect the AM antenna plug to the antenna pad of the FM-DW module. If the AM circuitry attenuates the FM signal, a separate FM antenna is required (a 120 ohms type is recommended yet a 3ft wire is sufficient in moste cases).


The FM-DW L OUT and R OUT pads will be connected to the AM Saver by vertical straps later.


The FM-DW Setup pad allows connecting an additional Setup push-button, which other end must be grounded.
The AM Saver has a hole allowing accessing the FM-DW push-button.


Mount the AM Saver module over the FM-DW module as shown in Fig. 4 using spacers (4mm external diameter) and ensure that they make no short-circuit with other pads. Verify that the grounds of both modules are connected together.


Fig. 4: AM Saver over the FM-DW 2.0 module.


Add a vertical strap between each of the four AM Saver pads circled in white and its corresponding FM-DW pad underneath.

The Amplifier L-R pads of the AM Saver must be connected to the LF amplifier input(s). With AC/DC radios, it is recommended to add a capacitor before the LF amplifier input(s) if not already present by design. The value is not critical (typically 10nF).
The Amplifier R pad is only required for radios equiped with a stereophonic amplifier.
The Amplifier L pad is used with mono receivers.

The AM Det. pad of the AM Saver must be connected to the AM detector (which must be disconnected from the LF Amplifier Input).

The Tuning Capacitor pad of the AM Saver connects to the oscillator section of the tuning capacitor through a short wire to avoid adding too much capacitance. Anything previously connected to this oscillator section must be connected to the AM Block pad of the AM Saver, except a capacitor trimmer which must remain connected to the tuning capacitor. Due to increased capacitance, the oscillator should be checked and eventually adjusted before the FM-DW setup. As a reminder, the Tuning Capacitor pad of the FM-DW module must only be connected to the AM Saver with a vertical strap.

The Vaccuum Tube pad is used only when the AM section produces harmonics perturbating the FM reception.
In this case, a small modification must be applied to the frenquency changer tube circuit as shown in Fig. 5:
The grid resistor (usually between 25K and 47K Ohms) must be left grounded. Disconnect the cathode from the ground, and add a 82 ohms resistor between the cathode and the pad designated by a vaccuum tube symbol. If the cathode was originally grounded through a parrallel resistor and capacitor, that resistor must be put in place of the 82 ohms resistor.


Fig. 5: AM Saver pads and optional circuit.


The two AM/FM Switch pads connect to an external switch enabling the AM bands when closed. Two terminals of the band selector may be used provided that they be never connected to anything whatever the switch position, and that they remain connected only at the positions corresponding to the AM bands. A microswitch (SPDT with lever) may also be used to detect the mechanical position of the FM band. Otherwise, a separate switch must be used.

Connect the 1µF capacitor between the upper AM/FM Switch pad as seen on Fig. 5 and the ground (either one of the three grounded corners, or very carefully at the negative side of the 820µF electrolytic).


D o u b l e     C h e c k     y o u r     w i r i n g
     before turning the radio on to configure the FM-DW module.

FM-DW 2.0 Setup and Reset procedures



Setup does not require the tubes to warm up, and the module won't tune before it completes.
Setup will resume in case of power loss. Parameters already set won't be lost.

The push-button is fragile. Do not press hard and do not use a sharp tool.
Presses must be quick and not exceed one second.

The FM-DW module can be reset at any time by pressing the push-button during at least two seconds.
It can also be cold-reset by keeping the push-button pressed while turning the radio on.
When reset, the status LED becomes green.


Step 1 (fixed green LED):
Position the dial where you want the FM band to start and press the push-button.

Step 2 (fixed blue LED):
Position the dial where you want the FM band to end and press the push-button.

Step 3 (blinking LED):
Choose the type of de-emphasis using the dial.
For 75µs (Americas and South Korea), move the dial over 98MHz so that the LED blinks in blue.
For 50µs (anywhere else), move the dial under 98MHz so that the LED blinks in green.
If the color doesn't change, test the tuning capacitor and verify your wiring.
Press the push-button.

Step 4 (twice-flashing LED):
To choose the type of sound output, move the dial under 98MHz for mono (green flashes) or over 98MHz for stereo (blue flashes). Press the push-button.

Step 5 (twinkling LED, only used with stereo output):
In stereo mode, a weak signal can add undesirable noise which may disappear in mono.
The Stereo Noise Control option allows switching to mono in this case.
Move the dial under 98MHz to disable the Steren Noise Control (green twinkles), or over 98MHz to activate it (blue twinkles). Press the push-button.


The setup is now complete: the LED should turn off and you should be able to receive the FM band.

1 FM-DW 2.0 module: 29,90€
4 FM-DW 2.0 modules: 119,60 € 109,90€
1 Combo (FM-DW 2.0 + AM Saver): 44,90€
4 Combos (2 panels): 179,60€ 169,90€
Prices include worldwire registered mail shipping.
Module(s) FM-DW 2.0 / AM Saver :

Configuring the FM-DW 1.0
(no longer supported)



The installation is almost same as with the FM-DW 2.0 module, except for the tuning capacitor which connects to the "CV" pad.

Two firmware versions exist for the FM-DW 1.0. Only the second (the most common) allowed choosing where the FM band starts and ends on the dial. Proceed the classic firmware setup. If the FM band is incorrectly covered or if the tuning does not work, overwrite the parameters by proceeding the early firmware setup.

The miniature calibration button is fragile and must be handled with care.
Do not use a sharp tool and do not press hard.
Turn the radio on. It is not required to wait for the tubes to warm up.

Classic firmware setup:
The calibration push-button must always be pressed gently and quickly for less than a second.
The module will not tune until full setup is performed.
- Set the dial where the FM band should start (87.5 MHz) and press the calibration button once.
- Set the dial where the FM band should end (108 MHz) and press the calibraiton button once.
Setup is now complete.

If you pressed the calibration button by mistake or by accident during one of the two above steps, or if you got lost, reset the FM-DW module as follows:
- Turn the radio OFF and wait for a few seconds.
- With the calibration button pressed, turn the radio ON. Release after a second.
- The FM-DW module is now reset and stays silent: turn the radio OFF before repeating the setup.

Early firmware setup:
Pressing the calibration push-button more than once during either step below won't alter the setup.
- Set the tuning capacitor to its maximum value (fully closed) and press the calibration button.
- Set the tuning capacitor to its minimum value (fully open) and press the calibration button.
Setup is now complete.