©2009 Hamtronics, Inc.; Hilton NY; USA. All rights reserved. Hamtronics is a registered trademark. Revised: 7/28/11
-Page 1-
Note about page numbers.
In order to accommodate various bands,
this manual has extra pages you may not re-
ceive for your version. The two meter version
will have pages numbered 1 through 7. Other
bands may have a higher number page substi-
tuted for the two meter parts list page, so
pages may not all be consecutive.
FUNCTIONAL DESCRIPTION.
The R100 is a commercial-grade single-
channel vhf fm receiver available in models for
various bands, both in kit form and factory
wired and tested.
The R100 features a front end with low-
noise dual gate fet's and triple-tuned circuits
for excellent sensitivity and rejection of out-
of-band interference. It has an 8-pole crystal
filter with steep skirts
plus a ceramic filter for
close channel spacing or repeater operation.
The i-f selectivity, for instance, is down over
100dB at ±12 kHz away from the carrier,
which is 40-50 dB better than most transceiv-
ers.
A new positive-acting, wide-range squelch
circuit locks onto fading signals. The R100 has
output terminals for low-level squelched au-
dio and discriminator audio as well as speaker
audio and a COS logic signal from the squelch
circuit.
ASSEMBLY.
General Information.
Note that vhf equipment requires pre-
cise construction using short, direct leads.
Seat parts as close to the board as possible
without over-stressing the leads.
Be sure to follow instructions as given and
don't arbitrarily do things differently.
When installing resistors and diodes that
are mounted vertically, be sure to orient the
body as shown by large circles in parts lo-
cation diagram.
Static handling precautions are re-
quired for the fet's. The small geometry and
high impedances make FET's heat and static
sensitive; so be careful. It is good to discharge
your hand to a grounded metal object just be-
fore picking up a transistor, and the use of a
grounded soldering iron is mandatory.
Assembly Procedure.
a.
Set board on bench or in holding jig
oriented as shown.
b.
Install phono jack J1, orienting the
center lug toward the inside of the board
where the large pad is located under the
board. Bend the center tab over against the
foil, and solder all tabs under board.
c.
Install FET's Q1 & Q2 from top of
board. ORIENT THEM AS SHOWN with the
long drain lead positioned as indicated. Note
that the LETTERING MUST BE UP, not against
the board. Gently bend the leads of the fet's
at right angles, and insert into the holes in the
board. Seat the transistors as close to board
as possible without straining leads. Solder
leads under board.
d.
The crystal filters must be installed
with uncoded ends to the outside world and
the terminals which are connected to each
other all with matching color dots. The idea is
to connect these tandem filters in the circuit
in the same sequence as they were matched
at the factory. Start with either filter having
only one color dot. Install in position FL1 with
color dot to the right as shown.
e.
Install the filter with the matching
color dot in position FL2 so that matching
color dots on FL1 and FL2 are adjacent to each
other.
f.
Likewise, install FL3 with upper color
dot to match right-hand dot on FL2. Then, in-
stall FL4 with only one remaining color dot ad-
jacent to matching color dot on FL3.
g.
Install ferrite beads Z1-Z4, and solder
leads to board.
h.
Install diodes CR1 and CR2, observing
polarity. Note that the banded ends of the di-
odes should be down.
i.
Install transistors Q3-Q5 and voltage
regulator U3, observing proper orientation.
j.
U1 and U2 have a dot over pin 1 or a
notch in that end for identification as shown
in diagram. Solder the ic’s in place, being
careful about polarity.
Also note that using a socket is not rec-
ommended for i-f amplifier U1 because of the
extra inductance the socket would add to the
high frequency circuits, and audio output ic U2
needs to be heatsunk to the ground plane on
the board. Therefore, ic sockets have not
been supplied.
k.
Install electrolytic capacitors, observ-
ing polarity.
l.
Install slug tuned coils and transform-
ers as shown, and install coil shields. The 2½
turn (red) coils come with shields already on
the coils; however, in some cases, the shield
must be removed and rotated 90° in order to
fit holes in pc board. The 6½ turn (blue) coils
have shields supplied separately.
Note: Wait to install L3 after all other
parts are installed. It is easier to install adja-
cent capacitors before L3 is mounted.
m. Make sure the coils and shields are
fully seated, and solder both shield lugs. (Do
not bend lugs over, but you can bend the coil
leads over a little to hold them in place while
soldering.)
o. Install socket pins at Y1. Cut socket
pins from carrier strip close to body. Rock
them while firmly pressing into board. They
will snap in place. Solder lightly under board
(to avoid solder filling crystal sockets).
p.
Install all remaining components as
per location diagram and parts list. Leave the
top leads of R3, R7, R13, and R18 about 1/8"
high to act as test points. R4 and R5 each use
two 6.8K resistors tack soldered together at
the top to give 14K total resistance.
q.
Install pots R10 and R20. They should
be held in position while soldering so shafts
are at right angles to board, thereby min-
imizing strain on leads when pots are later se-
cured to front panel.
r.
Install L3.
s.
Check over all parts and solder con-
nections. If you are missing any parts, check
to see if you have other parts left over. You
may have installed a wrong value somewhere;
so recheck all values looking for the missing
parts. Color codes and printed numbers are
difficult to read on many small parts, so spe-
cial care is sometimes needed to avoid mix-
ups. Note that on certain models, some parts
may be marked "not used" in the parts list.
CRYSTALS.
The channel crystal plugs into sockets on
the board. We can supply crystals for any fre-
quency desired. We recommend that any new
crystals be ordered directly from us to be sure
that they will perform properly over the -30 to
+60°C range for which the unit was designed.
If you do order elsewhere, be sure to supply
the following specs.
The receiver uses 32 pF parallel resonant
crystals in HC-25/u holders. Crystals operate
in the fundamental mode. The crystal fre-
quency is as noted in the table below. Fre-
quency tolerance is .001%. If you use an OV-1
crystal oven, specify a crystal with a 60°C
breakpoint.
Note: If your crystal has a metal base,
avoid pushing the crystal down tight against
the sockets. After installing a crystal, simply
lift it slightly to be sure the base doesn't touch
HAMTRONICS® R100 VHF FM RECEIVER:
ASSEMBLY, INSTALLATION, OPERATION, & MAINTENANCE
Specifications of Interest
Frequency Range:
R100-50, 46-54 MHz
R100-72, 72-76MHz
R100-144, 140-175 MHz
R100-220, 216-225 MHz
Sensitivity
(12dB SINAD): 0.15uV
Squelch Sensitivity:
0.1µV
Selectivity:
±12 kHz at -100dB
Modulation Acceptance
: ±7.5 kHz
IF Filters:
8 pole 10.7 MHz crystal filter plus
455 kHz ceramic filter.
Audio Output:
2 Watts (8 ohms).
Operating Power:
+13.6Vdc at 45-120 mA,
depending on audio level.
Size:
4 in. W x 3-7/16 in. D (plus pot. shafts)
