A Manhatten Rock Mite.

I've had it in my mind for some time now that I wanted to build another manhatten RockMite.

~ ~ ~

Effective June 1, 2004 and retroactively to all amateur transmitters installed
after Jan 1,2003,the FCC's spurious emissions requirement was modified to more
stringent standards. The RockMite design was 'legal' at the time of its introduction,
but now requires a minor modification to remain so. The following two components
should be installed in series between the RockMite (board) antenna connector
(center conductor). The new FCC requirements are satisfied once these components are in place.

20m: 82pf cap & 1.5uh RF choke
30m: 82pf cap & 3.3uh RF choke
40m: 150pf cap & 3.3uh RF choke
80m: 330pf cap & 5.6uh RF choke

D. Benson, K1SWL 9/5/06

~ ~ ~

Now to start!


I needed some 8 pin IC pads, but I'm out of them. So using a computer daughter card.
I've notched the gold plated pins for my usage.

Then cut them off and soldered those pads to an IC socket. Now I'm ready to go.

Note! I hi-lite every component as it is installed. That way I don't miss one. Maybe?

~ ~ ~

To begin I started on the circuitry around "U1" an SA602:
By installing:

Capacitor C1 (47pf),C2 (33pf), C102(0.01uf).
Diodes D1 & D2 (1N4148)
Resistor R3 (4.7K ohm)
Crystal Y1 (3.579mhz)


Front and rear views.

The schematic and the substrate.

~ ~ ~

Finishing the circuitry around "U1" an SA602:
By installing:

Capacitors C101 (0.01uf), C5 (0.1uf), C4 (.022uf), C3 (0.01uf).
Zener Diode D3 (5.1v).
Resistor R1 (1K ohm).


Front and rear views.


A 1N4007 diode was installed for polarity protection.

The schematic and the substrate.

Testing the work:
Source voltage was 11.49vdc
Junction of R1/1N4007 was 10.83 vdc.
U1 Pin 8 voltage was 5.08vdc

~ ~ ~

Now to install the "U2" circuitry an MC1458.

By installing:
Capacitors C6 (100pf), C8 (0.1uf).
Electrolytic capacitors C103 (47uf), C7 (47uf), C9 (3.3uf).
Resistors R5 (1m ohm), R2 (4.7K ohm), R6 (10 ohm), R4 (1m ohm),R7 (100K ohm).
Transistor Q1 <2N7000).
Diode D7 (1N4148).

Front and rear views.


The schematic and the substrate.

Testing the work:
Source voltage was 11.49vdc.
U2 Pin 8 voltage was 10.84vdc


IC's "U1" the SA602 and "U2" the MC1458 were installed.

Power applied. Headphones connected at the "AF" connection.
BCI and hum were heard at different points of the circuit.
Mixer and audio amplifier are working.


R5 and C6 were installed in this manner as a potentiometer will be used when mounted in an enclosure.

~ ~ ~

Now to install the "U3" circuitry a 12C508A IC.

By installing: Capacitors C104 (0.1uf), C105 (100pf), C106 (100pf) & C107 (100pf).
Resistor R8 (1K ohm), R9 (4.7K ohm).
Zener Diode (5.1v).
Transistor Q2 (2N700).

Front and rear views.


The schematic and the substrate.

Testing the work:
Source voltage was 12.02vdc.
U3 pin 1 voltage was 5.02 vdc.
Top of R8 was 12.02 vdc.
Top of R9 was 12.02 vdc.

~ ~ ~

Now the "LO" Local Oscillator
By installing:
Resistors R10 (100K ohm), R12 (22K ohm), R11 (47K ohm), R13 (1K ohm), R14(100 ohm).
Capacitors C10 (68pf), C11 (68pf), C12 (47pf), C108 (0.01uf).
Transistor Q4 (2N4401).
Varactor Diode D6 (MV1662).
Crystal Y2 (3.579 mhz).

Front and rear views.

The schematic and the substrate.

Testing the work:
Source voltage was 12.02 vdc.
Top of R11 was 12.02 vdc.


Checked the oscillator with the freq counter. It was on the money.
Then checked it using a Short Wave receiver. Again on the money.

~ ~ ~

Now the PA Driver "Q4" and circuitry and Q5.
By installing:
Capacitors C13 (0.01uf) & C110 (0.1uf).
Eleclytic capacitor C111 (47uf).
Resistors R15 (47K ohm), R15 (100 ohm) & R17 (100 ohm).
Transistor Q4 (2N4401) and Q5 (2N7000)

Front and rear views.


The schematic and the substrate.

~ ~ ~

Now the PA "Q6" and circuitry.
By installing:
Capacitor C14 (0.1uf).
Resistor R18 (I subbed a 5.6ohm for the 10 Ohm).
Diode D8 (1N4148).
Transistor Q6 (2N3053 wa subbed for the 2N2222a).
These two mods should increase the output power to just under 1 watt).

Front and rear views.

A side view of Q6 showing height of mounting.


The schematic and the substrate.


All that remains now is Wind and install the toroids
for "L1", "L2", "L3" and the addendum toroid I'll call "L4".
L to R L1=15uh (8T/FT37-43), L2=2.2uh (23T/T37-2), L3=2.2uh (23T/T37-2) & L4=5.6uh (34T/t37-2).

Inductor L1 and measurement along with C109 (0.1uf) installed.

Inductor L2 and measurement along with C15 (470pf) another view.

Inductor L3 and measurement along with C16 (1000pf) & C17 (471pf) another view.

Inductor L4 and measurement along with 30pf capacitor another view.

The schematic and the substrate.

The construction has been completed.

Now for the case.

Template made. Adjusted and fitted.


Attached to case and drilled.


Controls mounted. Installed and wired substrate>.

Labeled case. Now It's finished.

72 RC kc5wa