Ultrakurzwellen - Kleinfunkstation MAX (VHF Low Power Set MAX) ; produced by Autophon AG, Solothurn.
The portable VHF Wireless Station MAX has been constructed by Autophon in the years of late WWII and has been supplied in a small series of 48 sets in 1945/46. This very innovative but expensive system has been replaced by the VHF sets REX and FIX acquired much cheaper from U.S. surplus.
The VHF station operating im AM mode used a dipole antenna and was powered by a hand cranked generator.
The station is to be powered from a hand cranked or foot operated generator with the LT (5,1 +/- 0,3 V) / HT (150 +/- 15 V) voltages.
There is a small optical indicator on the generator informing you when the handle is cranked with enough speed.
The SE-110 / MAX set consists of a transceiver in a metal case in a small canvas bag (3,5 kg), a generator in another canvas bag (another 4,55 kg) and a third canvas bag with the accessories and spares, headphones, morse key, throat microphone and antenna and power cables. With it's 12,35 kg, this station was truly portable, specially compared to the "Tragbar Leicht" shortwave station with 90,7 kg or the VHF "Tragbar Leicht Dezimeter" with 167 kg.
The lid of the metal transceiver case is attached to the canvas bag, the transceiver comes with only four D1F battery tubes.
In the middle of the frontpanel of the transceiver, you find the frequency dial calibrated in MHz and with channel numbers, it can be mechanically locked. The „Empf.-Nachstellung“ in the right upper corner let's you adjust the frequency of the receiver section slightly for optimal readability.
The volume control is located in the left upper corner of the frontpanel, below the connectors for headphones, microphone and the morse key, and the power cable connector.
In the right lower part of the frontpanel, You find the transmit - receive switch („Senden / Empfang“) and the mode switch for telegraphy Tg (A2) and telephony Tf (A3). A measuring instrument will indicate the anode voltage when the red button is depressed.
The accessories are stored in the biggest of the three canvas bags: You find the headphones and throat microphone, the miniature morse key and cables to connect the generator and the transceiver and the latter with the dipole antenna. Of course, you find also a spares box with replacement tubes and a tiny screwdriver.
The generator is integrated in a similar canves bag. A mechanical indicator will inform you that the necessary cranking speed is reached. The generator can be operated hand cranked or foot operated, for this purpose, it has to be taken out of the canvas bag and can be fixed on a pair of skis, nowadays with the modern ski equipment, this won't be possible anymore.
The VHF set's range is typical to VHF radiowaves propagation: You can reach on visible points nearer then the horizon, so 100 m - 5 km when there is no line of sight, 8 km in telephony and 15 km in telegraphy from an elevated location and up to 30 km in telephony and 50 km in telegraphy from one mountain peak to another hill or exposed location.
In reception mode, the RF signal coming from the dipole antenna is fed directly to the mixer stage valve Pos. 15 (D1F), there it is mixed with the oscillator signal Pos. 44 (D1F) to generate the IF of 25 kHz. Because of the IF is quite low, a signal might appear a second time on the dial 25 kHz below the actual frequency dial reading. After having passed a IF filter, the signal is fed to the IF amplifier stage Pos. 64 (D1F), and from there to the regenerative detector stage Pos. 104 (D1F) for demodulation, after an AF amplifier, the audio signal is fed to the headphones.
In transmitting mode, the valve Pos. 44 (D1F) is acting as oscillator or driver stage, in valve Pos. 15 (D1F) acting as output stage, the RF signal is amplified.
The signal from the microphone is amplified in valve Pos. 64 (D1F), after a second amplifier stage valve Pos. 104 (D1F) the modulation of the output stage valve Pos. 15 (D1F) is done using a modulation transformer Pos. 106.
For A2 telegraphy the valve Pos. 104 (D1F) acts as audio generator, the valve Pos. 64 is not in use in this operation mode.
V15 (D1F, Transmitting: Output stage; receiving: mixer); V44 (D1F, transmitting: oscillator / driver stage; receiver: oscillator); V64 (D1F, transmitting: microphone amplifier; receiving: IF stage); V104 (D1F, transmitting: modulator stage; receiving: regenerative detector).
The UKW-Kleinfunkstation MAX has been developed by Autophon; after a first small batch had been delivered, the Swiss army preferred to acquire less costly frequency modulated VHF sets from U.S. surplus.
The VHF wireless station MAX has been introduced with the troops in 1945/6 but was replaced by frequency modulated VHF gear from U.S. Army war surplus available much cheaper then this Swiss made high tech offering.
According to the document „Funkstationen der Armee“, 48 sets for 3'750.- Fr. each have been ordered.