FM ATV Equipment

Here is some of the FM ATV equipment that I have been working with. Most of it is from G1MFG, but other suppliers offer the same, or similar, equipment which originates from Comtech, a Taiwan tuner manufacturer.

See Modification Page for schematics, technical information, problems and the  Platinum Mods .

13cm Receiver

Similar to the 23cm receiver, but with a switching voltage regulator.

13cm Receiver Schematic

13cm Receiver Tuner Schematic

GIMFG Instruction Sheets -

13cm Basic/Advanced Receiver Instructions

13cm ENG Receiver Instructions

13cm Transmitter Instructions

23cm Receiver

Similar to the 13cm receiver, but with linear voltage regulators.

23cm Receiver Schematic

23cm Receiver Tuner

GIMFG Instruction Sheets -

23cm Rx/Tx Instructions
Issue 4 from G1MFG web site

23cm Rx/Tx Instructions
Issue 1 from TVHam web site

Bottom View of 23cm Receiver
(Bottom of 13cm receiver is similar)

It was nice to see the PC boards designed with tuner mounting options in mind.

Receiver "S" Meter

Vertical installation of the tuner creates a perfect space to install a "S" meter on either the 13cm or 23cm receiver. See my

"S" Meter & Expanded Volt Meter Mod

It may appear that I can not resist re-installing tuners vertically. This 13cm tuner was reoriented in order to shorten the receiver length to permit installation in the Remote Controlled ATV Station.

13cm & 23cm Transmitters

The transmitters are identical except for
the transmitter module used.

13cm & 23cm Transmitter Schematic

13cm Transmitter Module Schematic

23cm Transmitter Module Schematic

See Companion Receivers (above) for  Transmitter Instruction Sheets.

Transmitter Modules

Some "bare" modules ordered for projects where space is limited and regulated 12V and an I2C interface is available to provide the transmit frequency data.


(left)   13cm & 23cm standard modules
(right) 13cm 200 mw module.

Simple 1/4 wave Dipole Antennas can be made using right angle SMA plugs and the center conductor with dielectric from RG-142 cable. When no longer required, the dipoles are easy to unsolder from the connector center pin leaving the connector free for more traditional usage.

23cm 1/4 wave Dipole Antenna
Length of the exposed element when tuned for 1250 MHz was 1.85".

13cm 1/4 wave Dipole Antenna
Element length tuned for 2340 MHz was 0.9".

13cm COP Receiver and 1W Transmitter

Receiver sensitivity is almost 12 dB less than the G1MFG receiver. Refer to the Receiver Sensitivity Comparison Table.


Receiver (right)


The transmitter looked small for 1 watt unit, especially without getting hot. I do not have a proper calibrated power meter, but determined that the transmitter, which runs cool, outputs almost 1.25 watts.

1 Watt Transmitter (below)

23 cm 20 Watt Power Amplifier
An excellent kit from DEMI.

Home Brew Dual Directional Coupler
Small electronic components can be hard to work with if you have vision problems and need an Austin Lasik procedure. Good light and a magnifying glass can help you see what you are doing, but correcting any vision problem will make the work easier and more enjoyable.