Heathkit Model IM-4100

Frequency Counter

Calibration Procedure

Ancillary Equipment Needed

AM Radio

General Coverage Communications Receiver

Frequency Counter

RF Generator

Laboratory Standard Frequency Source

* * * * * * *

WITHOUT INSTRUMENTS

Refer to Figures 4 & 6

Illustration booklet page 4

(    )         Set the POWER switch to the ON position

               (Allow the unit to warm up for 30 minutes)

(    )         Set the POWER/TIME BASE switch to the kHz position.

(    )         Set the MODE switch to the TOL position.

“Option 1”

Using a general coverage communications receiver

(    )         Set the receiver MODE switch to the AM position.

(    )         Tune the receiver to the highest WWV station that can be received.

               (Frequencies of: 25, 20, 15, 10, or 5 MHz)

“Option 2”

Using an AM Radio

(    )         Tune the radio to a station of known frequency and of medium volume.

* * * * * * *

(    )         Connect (temporarily) an insulated, unshielded wire to the receiver’s antenna terminal.

               (Leave the outside antenna connected to the receiver)

(    )         Lay the temporary wire over the oscillator section of the counter.

               (Refer to Figure 4 in the Illustration booklet)

(    )         A tone should be heard.

               (If a tone is not heard, remove the case, and place the wire near IC26 - 7400)

               [Left rear on the circuit board, see PICTORIAL 2-6]

(    )         Adjust the oscillator trimmer through OSC ADJ hole on rear panel using a non-conducting alignment tool until a zero bear is heard from the receiver.

(    )         Calibration procedure is complete.

* * * * * * *

WITH CALIBRATED INSTRUMENTS

Refer to Figure 5

Illustration booklet page 4

(    )         Set the POWER switch to the ON position

               (Allow the unit to warm up for 30 minutes)

(    )         Set the POWER/TIME BASE switch to the kHz position.

Using a Frequency Counter and an RF Signal Generator

(    )         Connect the RF Generator, reference Frequency Counter, and the Frequency Counter being calibrated as shown in Figure 5.

(    )         Set the RF Generator output frequency between 1 MHz and 30 MHz.

(    )         Set the RF Generator output voltage between 250 mV and 500 mV.

(    )         Adjust the oscillator trimmer through OSC ADJ hole on rear panel using a non-conducting alignment tool until the IM-4100 counter reading matches the reference counter reading.

(    )         Calibration procedure is complete.

Using a Known Laboratory Standard Frequency

(    )         Known laboratory standard frequency should be between 1 MHz and 30 MHz

(    )         Known laboratory standard frequency output voltage should be between 250 mV and 500 mV.

(    )         Connect the known laboratory standard frequency to the IM-4100.

(    )         Set the RF Generator output frequency between 1 MHz and 30 MHz

(    )         Adjust the oscillator trimmer through OSC ADJ hole on rear panel using a non-conducting alignment tool until the IM-4100 counter reading matches the known laboratory standard frequency.

(    )         Calibration procedure is complete.