FM-DW lets a vintage radio receive the FM band while preserving its original tuning mechanism, amplifier and loudspeaker.
Add the optional AM Saver to retain the AM bands, and use the regulated +5V output for a suitable small accessory such as Bluetooth.
The current modules share the same core FM functions. The important difference is how the module detects the dial position and which extra functions are required.
For radios equiped with an AM tuning capacitor.
For small transistor radios equiped with an AM tuning capacitor.
Adds support for variable-inductor and potentiometer tuning.
Can drive most magic eyes to indicate FM signal strength.
Fits above FM-DW 2.2, 2.3 and 3.0 and preserves the original AM bands with an AM/FM switch. Not compatible with FM-DW 2.3 MICRO.
| Feature | FM-DW 2.3 | FM-DW 2.3 MICRO | FM-DW 3.0 | AM Saver |
|---|---|---|---|---|
| Uses original radio dial and amplifier | Yes | Yes | Yes | Yes |
| AM tuning capacitor | Yes | Yes | Yes | Yes |
| Local Oscillator (LO) tuning | No | No | Yes | Yes |
| Potentiometer tuning (FM) | No | No | Yes | Potentiometer tunes FM only |
| Magic Eye FM signal indication | No | No | Yes | Can switch Magic Eye between AM and FM in LO mode |
| AM Saver compatibility | Yes | No | Yes | |
| +5V 80mA accessory supply | Yes | No | Yes | |
| Supports 1.5V-3V pocket radios | No | Yes | No |
The AM bands can be preserved using the optional AM Saver “piggy-back” module or a custom switching circuit.
DAB/DAB+ radios can only be heard using a DAB/DAB+ to FM transmitter, which avoids altering the radio to insert additional controls and an LCD screen.
The FM-DW has an on-board regulated +5V DC output that can power a Bluetooth receiver. On current modules the regulated output provides up to 80mA and requires at least 6V DC at the FM-DW supply.
Bluetooth audio is a separate audio source: it does not replace the FM tuning system or the radio’s original amplifier and loudspeaker.
You may use a Bluetooth module which automatically switches between its AUX input (usually connected to the FM-DW audio output) and Bluetooth audio when a Bluetooth connection is established.
Alternatively, unused contacts on the radio’s original band switch may be used to select manually between the FM-DW output and Bluetooth.
It is recommended to wire the audio switch so that, when one of the two audio sources is selected, the other is grounded to minimize crosstalk.
The FM-DW modules contain electrostatically sensitive components. To avoid damage, installation must be carried out by a technician with a strong electronics background (especially in the restoration of vintage tube and transistor radios) and under professional-grade ESD protection. Otherwise, you install and use the FM-DW modules at your own risk.
Each FM-DW module is tested individually before dispatch to avoid any defects on arrival. Any returned module will be closely inspected to determine whether it has been damaged by improper installation or tampering; if so, it will not be replaced or refunded.
Follow the complete installation sequence below for your selected FM-DW module.
Ensure that your radio has been properly restored and that its amplifier is working correctly.
Keep the radio unplugged from the mains throughout the entire installation process.
Your radio's mains switch must be clean and not produce excessive arcing.
If necessary, a suppressor capacitor can be connected in parallel.
Before all, the FM-DW module should be placed away from heat sources such as rectifier and output tubes. It is recommended to place it under the chassis. FM-DW modules from version 2.2 use a different FM chip, making them significantly more tolerant than the previous versions.
Except for vintage car and early transistor radios with positive ground, the FM-DW module should be grounded to the chassis. This is very important for AC/DC sets. Its three grounded holes allow a solid attachment.
For radios with positive ground — where the car chassis is connected to the positive side of the battery — ensure that none of the grounded holes of the FM-DW module are connected to the chassis. The FM-DW module is protected against reverse polarity.
The FM-DW AC/DC IN pad supplies the FM-DW module with AC (4V to 10V) or DC.
When the tube heaters are connected in parallel, the heater winding may be used to power the FM-DW module. The wiring depends on the type of winding and its voltage.
Radios with heaters connected in series must use a separate DC power supply that provides 6V to 9V DC with sufficient current:
For car radios, the AC/DC IN pad must be connected to the +6V or +12V supply.
The FM-DW 2.3 MICRO's ground pad is located above the tuning capacitor pad and has a larger hole.
The FM-DW 2.3 MICRO has two power inputs. Use only the input corresponding to the radio's supply voltage:
The FM-DW Setup pad allows the connection of an additional setup push-button, the other end of which must be grounded.
When AM Saver is fitted, the AM Saver has a hole to allow access to the FM-DW push-button.
The FM-DW 3.0 supports three modes for detecting the dial position and tuning to the corresponding FM channel. The selected operating mode is the same whether or not an AM Saver is fitted; only the wiring differs.
The default mode is Capacitive, which uses the AM tuning capacitor to detect the dial position.
The Local Oscillator (L.O.) mode allows the FM-DW 3.0 to work with most AM radios, including vintage car radios, whether they use a tuning capacitor or variable inductance for tuning.
The Resistive mode uses a linear potentiometer mechanically coupled to the dial mechanism.
To enable the L.O. mode, bridge the two halves of the Osc pad in the Mode section.
To enable the Resistive mode, bridge the two halves of the Pot pad in the Mode section.
FM-DW 2.3 MICRO has been designed to fit in compact radios, typically portable tube radios running on batteries and small transistor radios.
Unless you use your own AM / FM switch circuit, the AM bands are no longer used, and you can save some space by removing the IF sections (including the IF transformers).
For portable tube radios running on batteries:
The plate and screen grid circuits of the IF tubes can therefore be disconnected.
The IF section is no longer required. The plate and screen grid circuits of the IF tubes can therefore be disconnected.
Capacitive or Resistive mode: the IF sections are not required and can be disabled.
Local Oscillator (L.O.) mode: the L.O. section must remain operational; otherwise the module will halt. Later firmware versions cause the LED to alternate between green and blue every second until a relevant local oscillator signal is detected. The second IF stage can be disabled.
IF tubes can only be removed if their heaters are connected in parallel. The second IF tube must be left in place if it contains a triode that is used in the LF amplifier circuit.
If the high voltage (B+) increases too much after disabling the IF section, adjust the DC filter with a higher resistor, or add a resistor in series with the loudspeaker field coil.
For transistor radios:
The FM-DW Antenna pad is connected differently depending on your configuration.
Remove anything previously connected to the radio's antenna connector and connect it to the FM-DW Antenna pad.
For AC/DC radios, a 1 megohm resistor should be connected between the FM-DW antenna pad and the chassis.
A 120 ohm antenna is recommended; a 3ft cable is sufficient in most cases.
For car radios, disconnect the AM filter originally connected at the antenna input. This filter is usually made of a capacitor trimmer and an inductor, and can considerably attenuate the FM signal.
The FM-DW L OUT pad can be used with mono receivers. Radios equipped with a stereo amplifier will use it as the left channel source. Connect the L OUT pad to the LF amplifier input after disconnecting the detector circuit. For AC/DC radios, a 0.01µF/630V capacitor should be inserted before the amplifier input if not already present by design. Its value is not critical. A shielded cable should be used except for short lengths. Remember that only one end of the shield must be grounded.
The FM-DW R OUT pad is only required for radios equipped with a stereo amplifier. As with the L OUT pad, connect R OUT to the right channel input after checking that the detector circuit is no longer connected.
The local oscillator circuit is extremely sensitive and should be connected with care. To prevent parasitic capacitance from altering the signal, connect the L.O. signal from the AM tuner to the octagonal Osc pad, under the Antenna pad, using the shortest possible wire, and avoid placing the wire close to other wires or near metal parts.
On tube radios, the L.O. signal is located at the grid of the oscillator tube.
On transistor radios equipped with variable inductors, the L.O. signal is located at the oscillator coil connected to the oscillator transistor. This transistor is usually located between the first one, often called the RF Amplifier, and the third one, often called the Mixer, itself just before the first IF transformer.
On transistor radios equipped with a tuning capacitor, the L.O. signal is easily found at one of the tuning capacitor sections.
If in doubt, the L.O. signal can easily be found using an oscilloscope.
The condition of the tuning capacitor is critical. Permanent contact between the shaft and the collectors is essential. Ensure that there is no excessive dust between the plates and that there are no short-circuits when the tuning capacitor is rotated from end to end. Either fault can distort capacitance measurements and make tuning unstable or impossible.
The body of the tuning capacitor must be grounded, and all ground points should be connected, which will reduce weak collector contacts.
For positive chassis sets (some vintage car and transistor radios), isolate the tuning capacitor's body and ground it. If not possible by design, the set can only be converted using the FM-DW 3.0 in Local Oscillator mode.
Ensure that the fixed plates of the tuning capacitor are not originally connected to a high voltage source; otherwise the FM-DW module will be permanently damaged by residual charges when switching between AM and FM.
The tuning capacitor must be connected to the FM-DW module pad marked with a variable capacitor symbol. Nothing else should be left connected to the tuning capacitor, except capacitive trimmers which can be set to their maximum.
Grouping the sections of the tuning capacitor is not essential, but may be necessary in some cases: the minimum capacitance should be 40pF to 100pF — add a small fixed capacitor in parallel if necessary — and the maximum capacitance should be 500pF to 800pF.
Solder a vertical strap between the AM Saver pad located below the two AM/FM Switch pads and the FM-DW Tuning Capacitor pad.
Disconnect what was originally connected to the oscillator section of the tuning capacitor, except capacitive trimmers, and connect it to the AM Block pad of the AM Saver with the shortest possible wire.
Connect the freed oscillator section of the tuning capacitor to the Tuning Capacitor pad of the AM Saver with the shortest possible wire to avoid adding too much capacitance.
Due to the increased capacitance, the AM local oscillator should be checked and possibly adjusted prior to the FM-DW setup.
The tuning is done using a 10K to 50K linear potentiometer, which must not produce jitter.
The potentiometer connects to the three holes marked Tuning Pot (cursor at the center, the other two ends to the remaining holes in no particular order).
The potentiometer can replace a damaged tuning capacitor provided that the original dial cord pulley be attached to its shaft (metal type is recommended).
The potentiometer must be mechanically coupled to the AM tuning system.
For AC/DC radios, a 1 megohm resistor should be connected between the FM-DW antenna pad and the chassis.
A separate FM antenna is recommended if the AM circuitry attenuates the FM signal.
A 120 ohm antenna is recommended; a 3ft cable is sufficient in most cases.
The FM-DW Magic Eye pad allows the Magic Eye tube to be used as an FM signal strength indicator provided that the triode section is not used as an LF preamplifier. Otherwise, the Magic Eye circuitry must be modified using a separate LF preamplifier.
Disconnect the grid of the Magic Eye tube from the AM circuits, and connect the Magic Eye pad to it instead. Most types of Magic Eye tubes used in old AM radios are supported, with maximum grid voltage adjustable to -10 volts during setup.
In Capacitive mode, the Magic Eye tube cannot be used as an FM signal strength indicator unless it is permanently disconnected from the AGC circuit of the AM section.
In Local Oscillator mode, the Magic Eye tube can be used to indicate FM signal strength because the AM Saver can switch its grid connection between the AM and FM circuits.
Connect the AM Saver pad located below the two AM/FM Switch pads to the FM-DW Magic Eye pad.
Connect the wire that was originally connected to the Magic Eye tube grid to the AM Block pad of the AM Saver.
Connect the Magic Eye tube grid to the AM Saver Tuning Capacitor pad.
The FM-DW Antenna pad connects to the radio's antenna connector.
For vintage car radios, the vehicle's antenna should be used.
Mount the AM Saver module on top of the FM-DW module using metal spacers with a 4mm outer diameter, ensuring that they do not short-circuit other pads as they connect the grounds of the two modules.
Connect the 1µF capacitor as shown in Fig. 5.
The AM Saver accepts 4 to 6 volts AC or DC. In this case, a vertical strap must be placed between the AC/DC IN pads of the two modules.
If the FM-DW module is supplied with more than 6V AC, a rectifier diode must be used instead of the strap, with the anode connected to the FM-DW module. This diode must have a voltage drop of 0.6V to 1.2V and a forward current of at least 200mA. Additional series-connected diodes are required if the FM-DW module is powered from a higher voltage.
Ensure that there is not more than 6V DC at the main electrolytic capacitor of the AM Saver module. Excessive voltage will cause the on-board regulator to overheat and shut down for protection.
Depending on your configuration, several vertical straps must be connected between the AM Saver pads circled in white and the corresponding FM-DW pads underneath.
Strap each of the two AM Saver pads on the right with its corresponding FM-DW Audio Out pad.
The Amplifier L-R pads of the AM Saver must be connected to the LF amplifier input(s). Shielded cable(s) should be used except for short lengths. Remember that only one end of the shield must be grounded.
The Amplifier R pad is only required for radios equipped with a stereophonic amplifier. The Amplifier L pad is used with mono receivers.
For AC/DC radios, a 0.01µF/630V capacitor should be inserted before the amplifier input if not already present by design. Its value is not critical.
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 Vacuum Tube pad is used only when the AM section perturbs FM reception. In that case, a small modification must be applied to the frequency-changer tube circuit as shown in Fig. 5.
The grid resistor, usually 25K to 47K ohms, must be left grounded.
If originally grounded, disconnect the cathode from ground and add an 82-ohm resistor between the cathode and the AM Saver pad designated by a vacuum-tube symbol.
If the cathode was originally grounded through a parallel resistor and capacitor, or a resistor alone, disconnect them — or the resistor — from ground, and connect them — or the resistor — to the AM Saver pad designated by a vacuum-tube symbol.
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 are never connected to anything else 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.
The FM-DW Antenna pad is connected differently depending on your configuration.
Remove anything previously connected to the radio's antenna connector and connect it to the FM-DW Antenna pad.
Before setup: if present, vacuum tubes don't need to warm up, and the module won't tune until the setup is complete. Setup will resume in the event of a power failure; parameters already set won't be lost.
The push-button is fragile. Do not press hard or use a sharp tool. Press quickly, typically less than one second.
When using the AM Saver module, FM mode must be enabled before proceeding.
If using FM-DW 3.0 in Local Oscillator mode, ensure that the radio's local oscillator section is functional.
FM-DW modules from version 2.2 use a more sophisticated FM chip. A sudden drop in supply voltage, or turning the radio back on too quickly after switching it off, may prevent the FM chip from operating normally, rendering the module mute and/or the push-button inactive.
In this case, switch off the radio. If the module is powered from the heating circuit, switch the radio back on after 3 seconds. Otherwise, wait until the DC voltage supplying the module is discharged.
FM-DW modules supplied after 09/25/2024 use the blue LED to indicate a problem:
If the LED remains blue during one of the above steps, switch the radio off and on again as described above.
If the problem persists, check the condition and operation of the tuning capacitor, and the module installation.
As a reminder, modules are individually tested before shipping to the customer.
Choose the dial position where the FM band starts and press the push-button.
Choose the dial position where the FM band ends and press the push-button.
Use the dial to set the FM band type according to the blinking LED pattern:
If the color doesn't change, test the tuning capacitor (or the Local Oscillator circuit when used with FM-DW 3.0), and verify your wiring.
The next step will be ignored with Japanese FM bands. Press the push-button.
Use the dial to set the de-emphasis according to the blinking LED color:
This step is ignored with FM-DW 2.3 MICRO (mono only).
Use the dial to set the sound output type according to the LED color:
Press the push-button.
Use the dial to set the AFC — Automatic Frequency Correction — mode depending on the LED color:
Press the push-button.
FM-DW 2.3 / 2.2: setup is now complete. The LED should turn off and you should be able to receive the FM band.
The FM-DW 3.0 setup procedure differs from FM-DW 2 only by this additional step.
Press the button to complete the setup: the LED should turn off and you should be able to receive the FM band.
A special Test and Reset mode can be accessed at any time by pressing the button for at least two seconds.
With FM-DW 2.2 and later modules, the LED flashes green when the button can be released.
The LED will then alternate between blue, green and OFF. Depending on the status of the LED, the following action is performed when pressing the button:
The module scans the FM band without using the tuning capacitor, and tunes to channels with sufficient level for two seconds. Strong channels can cause the module to tune below and/or above their frequency, giving the impression of tuning twice or three times.
FM-DW modules dated from 2025 use a manual tuning method: starting at the beginning of the FM band, they tune 100kHz further after each short press of the button.
To exit, press the button until the FM is muted. The module will resume its previous operation — FM reception or setup.
The module is reset, the LED goes OFF quickly and the setup starts again from Step 1 with a green LED.
Exit from Test / Reset mode. The module resumes its previous operation — FM reception or setup.
This method should only be used if the module does not respond after being powered up.
FM-DW 2.1 and 2.2 dated up to 2024 will enter the Test & Reset mode described above.
Since 2025, all FM-DW modules are reset immediately after releasing the button. The LED turns blue for half a second while the FM chip is initialising, and turns green when the module starts the setup procedure.
The live PayPal forms from the existing site can be inserted into the three product cards below.
Important note for US buyers:
Due to recent changes to shipping rules, shipping to the United States has become significantly more expensive than the registered-mail rates previously used: package rates are now mandatory, with import taxes paid upfront.Choose one option to display the appropriate ordering method.
4 modules: €109.90
4 modules: €189.00
1 Combo 2.3: €44.90
4 Combos 2.3: €169.90
1 Combo 3.0: €64.00
4 Combos 3.0: €239.00
Choose the dial position where the FM starts and press the push-button. Setting the dial at an extreme position is not recommended.
Choose the dial position where the FM band ends and press the push-button.
Use the dial to set de-emphasis. 75µs — Americas and South Korea — is blue; 50µs — anywhere else — is green. If the color doesn't change, test the tuning capacitor and verify your wiring. Press the push-button.
Use the dial to set the sound output type. Mono uses green flashes; stereo uses blue flashes. The next step will be skipped in mono operation. Press the push-button.
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 below 98MHz to disable Stereo Noise Control — green twinkles — or above 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.
FM-DW 2.0 reset: press the button for at least two seconds, or cold-reset by keeping the button pressed while turning the radio on. When reset, the status LED will turn green and setup can be performed again.
FM-DW 2.1 reset: read the reset procedure in the current Setup & Reset section.
The installation is almost the same as with the FM-DW 2.2 / 2.3 modules, 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 with the classic firmware setup. If the FM band is incorrectly covered or if the tuning does not work, overwrite the parameters by proceeding with 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.
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.
Setup is now complete.
If you pressed the calibration button by mistake or by accident during either step, or if you got lost, reset the FM-DW module as follows:
Pressing the calibration push-button more than once during either step below won't alter the setup.
Setup is now complete.