Asymod IIIs User manual
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Index
General Description…………………………………………….………………………………………………………3
Terminal, Component, and Adjustment Locations………………………………………………………4
Typical Single and Dual Final Installation…………….………………………………………………………5
A Word about Bias……………………………………………………………………………………………………..6
Asymod IIIs Installations………………………………….……………………………………………….…….32
Asymod IIIs Microphone Preamplifier Installation and Power On Options……………..57
Asymod IIIs & Stryker SR-955HPC Installation + eSSB……………………………………….…….32
Asymod IIIs & Stryker SR-955HPC + eSSB Settings & Specifications………………………...34
Asymod IIIs & Cobra 2000GTL Installation + eSSB Settings & Specifications…………...41
Asymod III installations (Asymod IIIs Installations start on page 32)……………………………7
Basic Installation for Stryker SR-955 HPC……….……………………………………………………………7
Advanced Installation with DPDT Relay for Stryker SR-955 HPC ………………………………...9
Advanced Installation with DPDT Switch for Stryker SR-955 HPC..…………………………….10
Stryker SR-995HPC PA Schematic………………………………………………………………………………12
Modulator Output & Configurations..……………………………….……………………………………….12
Audio Input Connections and Mic Jack Configurations.………………………………………….8, 16
PTT / MOX Operation.……………….……………………………………………………………………………….15
Microphone Installation……………………………………………………………………………..……………..16
Installation Block Diagram………………………………………………………………………………………….17
Installation for other Transceivers……………………………………………………………………………..18
Cobra Installation Section…………………………………………………………………………………………..19
Galaxy Installation Section………………………………………………………………………………………....22
Basic Installation with Bias Modification…………………………………………………………………....23
Dual Final Basic Installation with Bias Mod ……………………………………..…………………........25
Single Final Basic Installation with Bias Mod ………………………………………..…………………...26
Single and Dual FET and Transistor Installation with Bias Mod……………………………………27
Advanced Installation with Bias Switching Modification……………………………………………..28
Ultimate Installation with Auto Bias Switching Modification…….……………………………….29
Outboard Potentiometer installation……………………………………..………………………………….30
DC-DC Boost Converter Step-up Module LM2587/ XL6009…..…………………………………….31
Audio………………………………………………………………………………………………………………………….49
Installation Pictures
Galaxy Pluto –Configuration B Installation Pictures (Asymod III) …………………………..….50
Galaxy DX 77HML - Configuration C Installation Pictures (Asymod III)………………..……..52
RCI Ranger 2950 - Configuration C Installation Pictures (Asymod III) ……………..……....54
Mounting Hardware…………………………………………………………………………………………………..56
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General Description
The Asymod IIIs compact design makes it ideal for mobile and base station operation and allows for
internal mounting and simple installation in the transceiver with the included hardware and only
requires a 12 Volt supply.
Improvements in the Asymod IIIs Include selectable passive and active low pass filters, Remote Control
on board Solid State switch for ease of installation on multimode transceivers, enhanced RF suppression
and single-supply design providing quieter very low noise operation. New onboard preamplifier with
independent input and output to be used in any installation where audio levels need to be matched as it
applies to the SSB Balanced Modulator input levels or as a microphone preamp in series-loop
configuration into the Line-In input. See the Asymod IIIs Description Manual for more details.
The Asymod IIIs allows for amplitudes in excess of positive 300% modulation while not exceeding the
negative peaks at negative 100%. The Asymod IIIs is compatible with most transceivers and it is fully
adjustable via the onboard controls and accepts microphone and line level inputs. It offers the flexibility
to use a stock hand microphone to a high end audio processing chain using a broadcast microphone.
This unit will work with all High Level Modulation transceivers by direct coupling to the driver and final’s
collectors via the existing transceiver's onboard RF chokes without the need for a heavy, costly and large
modulation transformer. Low Level Modulation transceivers will require some modification. Instructions
for specific multiband HF transceivers is available upon request.
The Asymod IIIs produces modulation levels well above the norm and broadcast levels without
distortion, allowing for your station to sound loud and clean. With the Asymod IIIs connected to your
audio processing chain and a transceiver of your choice, your mobile or base station will sound just as or
better than commercial broadcast stations.
The Asymod IIIs can be readily interfaced with most high level modulation transceivers and its compact
design allows for internal mounting inside the transceiver. This manual is partially based on an
installation for a Stryker SR-955 HPC transceiver. These instructions can be applied to most makes and
models by following the general guidelines implied herein. Installation instructions and insertion points
for other makes and models can be found starting on page 18 of this manual. To achieve optimum
results, an adequate AM audio process chain catered to emphasize on your natural voice is highly
recommended. For advice on Hi-Fi audio processing, Please visit http://www.nu9n.com/am.html. If in
doubt, you may request specific transceiver installation instructions including low level modulation
transceivers, such as, multiband / multimode HF rigs.
NOTE: IMPORTANT
The transceiver/radio is only the exciter and should not be expected to generate high levels of RF power,
it should be expected, however, to generate a clean, perfectly modulated wide-band Hi-Fi audio and RF
signal well within the limits of the headroom available without pinching or clipping which can be later
amplified with a class AB or C, RF power amplifier and is best heard or monitored on a good quality
receiver equipped with a 6 kHz AM wideband receive filter and monitored on an oscilloscope. Audio
processing and a high quality microphone is strongly recommended for optimum performance. Audio
processing for mobile operation is possible with the use of the iRig PRE or iRig PRO interface using the
companion IK Multimedia's VocalLive Vocal Processor and Recording Studio app on your iOS device.
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Audio processing for base operation is possible with the use of rack audio processing gear or computer
based processing such as ProTools for PC or Mac along with the companion interface such as the Mbox 2
Mini or newer. The Asymod IIIs is NOT designed to give transceivers more RF power, more swing, or loud
distorted modulation, as many, which are not accustomed to, or appreciate the high fidelity audio
desire.
The Asymod IIIs may be set up in one of the three following configurations:
A- Single MJE3055T transistor (Q2) with a maximum collector current of 10 Amps.
B- Dual MJE3055T transistor (Q2 & Q3) with a maximum collector current of 20 Amps. (Request)
C- Single TIP35C transistor (Q4) with a maximum collector current of 25 Amps. (Request)
Although configuration A will work fine with most 4 watt transceivers, for heavy use, configurations B or
C is recommended which withstand higher duty cycles at lower temperatures and are available upon
request.
NOT FOLLOWING THE INSTRUCTIONS ON THIS MANUAL MAY LEAD TO PERMANENT DAMAGE TO THE
ASYMOD IIIs UNIT!
Make sure to follow the wiring instructions in this manual every time the unit is installed.
Terminal, Component, and Adjustment Locations
IMPORTANT: The modulator’s output transistors, Q2, Q2+Q3 or Q4, whichever combination
used, must be mounted on a reasonable size heatsink to maintain operating temperature to a
minimum. Ventilation is recommended.
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A Word about Bias
The ideal rig to use with the Asymod IIIS, is a dual final, single mode, AM only transceiver. Class C bias or
close to it should be employed in multimode transceivers RF final stages to allow for -100% modulation
peaks and achieve the correct asymmetry. Because modes such as SSB requires higher bias levels, such
as, class AB, modifications and/or adjustments may need to be performed on some multimode (SSB,
CW, etc.) transceivers.
A few multimode transceivers, such as the Stryker SR-955 HPC, Magnum 257/HP or the CRE-9800
automatically adjust the final bias according to the mode set, therefore modification to the RF final bias
circuit is not necessary in such case. In most other multimode transceivers slight modification to the RF
final stage might be required to employ Class C bias or close to it.
When using multimode transceivers (SSB, CW, Etc.), in the case where -100% modulation peaks cannot
be achieved, it will be due to the RF final bias levels set too high, in which case some modification or
adjustments must be performed. An ideal class C biased AM transceiver and more information regarding
bias settings and bias modifications for various multimode transceivers begin on page 23 of this manual.
Fig. 11 shows a perfect example of a Class C biased RF final stage. L35 and L47 pull the bases of TR43 and
TR44 far down and the Q-point is set some way below the cut-off point in the DC load line. As a result
the transistors will start conducting only after the input signal amplitude has risen above the base
emitter voltage (Vbe~0.7V).
To modify the bias on any multimode transceiver, RF chokes such as L35 and L47 seen in Fig. 11 must be
employed. Typically a 22uH inductor from the bases to ground will do. Simply remove the RF chokes on
the multimode transceivers providing the present bias and connect them to ground in the same manner
as L35 and L47 in the Galaxy DX 44 as seen on Fig 11.
In the case where -100% modulation cannot be achieved in any one of the Advanced Installations for
multimode transceivers presented in this manual, 99.9% of the time will be a bias issue. In such case, the
bias has to be adjusted. To avoid having to adjust the bias and keep all modes with their corresponding
bias levels, a relay or switch has to be employed for the bias section, as seen on the Advanced and
Ultimate Installations with Bias Modification starting on page 28. This will allow to switch from the
factory bias configuration to Class C bias when in AM mode using the 22uH inductors seen in fig 12.
Installations with bias switching capabilities are available starting on page 29, in the Advanced and
Ultimate Installation with Bias Modification sections.
NOTE: Asymod III section - Asymod IIIs Installations start on
page 32
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Basic Installation for Stryker SR-955 HPC
The following installations shown below are with the predecessor, the Asymod III, which is very similar
and contain other useful related information. Please refer to page 32 for the Asymod IIIs up do date
installation for the Stryker SR-955 HPC which do not require switches or relays for the advanced
installation.
Note: Basic installation allows for only AM mode transmit and receive using the Asymod III and will
restrict SSB and FM to only receive. To avoid this restriction, refer to the advanced installation section.
Refer to FIG. 1
1- Remove jumpers J3 and J4 located towards the rear of the transceiver. NOTE: for regular stock
AM use, including SSB and FM, these jumpers must be in their original factory location and the
Asymod III fully disconnected. To use the Asymod III and maintain full SSB and FM functionality
the advanced installation must be performed beginning on page 9.
Refer to FIG. 2
2- Run a wire from the Asymod III, + HI-OUT (3) to the insertion point, J3 pin 1.
3- Run a wire from the Asymod III, OUT- (4) to point Cor D(Chassis Ground).
4- Run a wire from L32 to J4 pin 2 as shown.
5- Run a wire from the anode of D515 to the Asymod III +12V input (1) terminal and connect the –
input (2) terminal to point Cor D(Chassis Ground) as shown.
6- Please refer to FIG. 3 for audio input connections. Connect the audio output from your
microphone or audio processing chain to the Line In terminals 5and 6. You can run the audio in
through the rear of the transceiver using a ¼” female phono chassis mount jack, or if you prefer
to use the transceiver’s hand mic, other microphone or line out from you audio process chain
connected directly to the mic jack of the transceiver, refer to FIG.3A, and install a shielded audio
cable from TP900, located toward the front of the transceiver to the Asymod III Line In terminal
5.
7- With this configuration the transceiver will only transmit on AM via the Asymod III and will be
only capable to receive on FM and SSB.
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Audio Input Connections
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Advanced Installation with DPDT Relay for Stryker SR-955 HPC
Refer to FIG. 1
1- Remove jumpers J3 and J4. NOTE: for regular stock AM use, including SSB and FM, these
jumpers must be in their original factory location and the Asymod III fully disconnected. To use
the Asymod III and maintain SSB and FM functionality this or the DPDT Switch advanced
installation bellow must be performed beginning on page 8.
Refer to FIG. 4
2- Run a wire from the Asymod III, HI-OUT+ terminal (3) to RL1 pin A2 as shown.
3- Run a wire from the Asymod III, HI-OUT- terminal (4) to point Cor D(Chassis Ground).
4- Run a wire from the anode of D515 (FIG. 2) to the Asymod III +12V input (1) terminal and
connect the –input (2) terminal to point Cor D(Chassis Ground) as shown.
5- Run a wire from L32, point E (+12v) to RL1 pin B2 as shown.
6- Run the rest of the wires from RL1 to J3 and J4 as shown.
7- Connect one side of a SPST mini switch to L32, point E (+12v) and connect the other side to RL1,
pin F(coil), connect RL1, pin G to point Cor D(Chassis Ground). Add D1, a 1 Amp, general
purpose diode as shown.
8- Please refer to FIG. 3 for audio input connections. Connect the audio output from your
microphone or audio processing chain to the Line In terminals 5and 6. You can run the audio in
through the rear of the transceiver using a ¼” female phono chassis mount jack, or if you prefer
to use the transceiver’s hand mic, other microphone or line out from you audio process chain
connected directly to the mic jack of the transceiver, refer to FIG.3A, and install a shielded audio
cable from TP900, located toward the front of the transceiver to the Asymod III Line In terminal
5.
9- With this configuration:
When SW1 is open (off), the Asymod III is disabled and the transceiver function normally on all
modes as it comes from the factory.
When SW1 is closed (on) the relay is activated and the driver and final are diverted to the
Asymod III and to +12 volts. At this point, the Asymod is enabled and the mode switch must be
set to AM. The transceiver will only transmit on AM via the Asymod III and will be only capable
to receive on FM and SSB.
RL1 (de-energized) = stock operation
RL1 (energized) = Asymod III enabled
SW1 open = stock operation
SW1 closed = Asymod III enabled
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Advanced Installation with DPDT Switch.
Refer to FIG. 1
1- Remove jumpers J3 and J4. NOTE: for regular stock AM use, including SSB and FM, these
jumpers must be in their original factory location and the Asymod III fully disconnected. To use
the Asymod III and maintain SSB and FM functionality this or the DPDT Relay advanced
installation above must be performed beginning on page 8.
Refer to FIG. 5
2- Run a wire from the Asymod III, HI-OUT+ (3) terminal to SW2 pin A2 as shown.
3- Run a wire from the Asymod III, HI-OUT- (4) terminal to point Cor D(Chassis Ground).
4- Run a wire from the anode of D515 (FIG.2) to the Asymod III +12V input (1) terminal and
connect the –input (2) terminal to point Cor D(Chassis Ground) as shown.
5- Run a wire from L32, point E (+12v) to SW2 pin B2 as shown
6- Run the rest of the wires from SW2 to J3 and J4 as shown.
7- Please refer to FIG. 3 for audio input connections. Connect the Audio output of your audio
processing chain to the Line In terminals 5and 6. If you prefer to use the transceiver’s hand mic
or any other microphone connected directly to the mic jack of the transceiver, install a shielded
audio cable from TP900, located toward the front of the transceiver to the Line In terminal 5.
8- With this configuration:
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When SW2 is in the UP position the Asymod III is disabled and the transceiver will function
normally on all modes as it comes from the factory.
When SW2 is in the DOWN position the driver and final are diverted to the Asymod III. At this
point, the Asymod III is enabled and the mode switch must be set to AM. The transceiver will
only transmit on AM via the Asymod III and will be only capable to receive on FM and SSB.
SW2 UP = stock operation
SW2 DOWN = Asymod III enabled
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Stryker SR-995HPC PA Schematic
Modulator Output
NOTE:
IMPORTANT
The Asymod III offers the flexibility to choose from 3 final modulating stage transistor onboard
configurations, allowing for TO-220 or TO-247 package transistors. To avoid permanent damage to the
onboard DC/DC converter, do not exceed a 1 Watt carrier (dead key) on a single final transceiver, and
a 2 Watt carrier (dead key) for a dual final transceiver. Always check for shorts after installing the
modulating stage transistor/s to the transceiver’s chassis or heatsink with the provided hardware and
before powering up.
Although the onboard DC/DC converter can supply a maximum of 25 volts at 5 amps, it is imperative to
maintain the maximum carrier levels at 1 Watt for single final and 2 Watts for dual final transceivers to
avoid damage. However, If higher carrier (dead key) levels are required, the use of parallel or larger final
modulating stage transistors (configuration B or C) allows for cooler operation and higher RF power
levels, and if is so needed, in such cases an external 24V supply should be used, refer to Fig. 28 on page
32. The Asymod III is equipped with onboard terminal connection solder pads for external -15volts,
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+15volts, +24 volts supplies which are located under the DC/DC converter and at the bottom/copper
side of the board. Please refer to the DC/DC converter section on page 32 for details.
The Asymod III may be set up in any one of the three following onboard configurations:
A- Single MJE3055T transistor (T2) with a maximum collector current of 10 Amps. (Standard)
B- Dual MJE3055T transistor (T1 & T2) with a maximum collector current of 20 Amps. (Request)
C- Single TIP35C transistor (T3) with a maximum collector current of 25 Amps. (Request)
Although configuration A will work fine with most 4 watt transceivers, for heavy use, configurations B or
C are recommended which withstand higher duty cycles at lower temperatures and are available upon
request.
Although the Asymod III will perform well with the modulating stage transistor/s onboard mounted on
an adequate heatsink or the transceiver’s chassis which can provide proper cooling, the final modulating
stage transistor/s may be mounted outside of the board and on the heatsink of the transceiver or other
enclosure with the appropriate cooling using wire extensions.
Configuration A
When using configuration A, make sure to secure the board and T2 well with the mounting hardware
provided. You may install T2 outside the board on the transceiver’s heatsink or chassis using wire
extensions.
Configuration B
When using configuration B, make sure to secure the board and both T1 and T2 well with the mounting
hardware provided. You may install T1 and T2 outside the board on the transceiver’s heatsink or chassis
using wire extensions. Alternatively, you may install T1 and T2 in parallel with more transistors of the
same part number combined with .1 Ω / 5W resistors as seen on FIG. 5C.
Configuration C
When using configuration C, make sure to secure the board and T3 well with the mounting hardware
provided. You may install T3 outside the board on the transceiver’s heatsink or chassis using wire
extensions. Alternatively, you may install T3 in parallel with more transistors of the same part number
combined with .1 Ω / 10W resistors as seen on FIG. 5D. The TIP35C has a maximum collector current
rating of 25 Amps, and is sure to withstand higher duty cycles at lower temperatures.
Make sure that the modulating stage transistor/s are securely mounted with the appropriate mounting
hardware provided; thermal silicone rubber & fiberglass composite insulator pad, bushing, and screw.
Make sure the modulating stage transistor/s are mounted to a large enough heatsink or part of the
transceiver’s chassis to sufficiently dissipate the heat. It is recommended to place the transceiver in
ventilated area. The use of a cooling fan is recommended for heavy use. Make sure the board has all the
support screws installed with the necessary hardware including any brackets, stands-offs, spacers, and
that the board mounting screw hole pads have good contact with the enclosure chassis. If the
modulating stage transistor/s are mounted externally, check for shorts and make sure all the wire
connections are firm and ran correctly before powering up.
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PTT / MOX operation
The Asymod III accepts both Line and Microphone level inputs. The audio can be fed in any one of
following various ways in combination with your preferred method for transmission activation, or PTT
(Push to Talk). For details regarding microphone connection via the transceiver’s microphone jack please
refer to FIG. 7A –7F.
1- From the output of the audio processing chain and connected in through the rear of the
transceiver and into the Asymod III. A momentary switch, a hand mic or desk mic connected to
the transceiver’s microphone jack for PTT.
2- From the output of the audio processing chain and connected in through the transceiver’s
microphone jack and into the Asymod III. A momentary switch also connected to the
transceiver’s microphone jack for PTT.
3- From a microphone, such as a sure SM58, connected in through the rear of the transceiver and
into the Asymod III. A momentary switch, a hand mic or desk mic connected to the transceiver’s
microphone jack for PTT.
4- From a microphone, such as a sure SM58, connected in through the transceiver’s microphone
jack and into the Asymod III. A momentary switch also connected to the transceiver’s
microphone jack for PTT.
5- From a stock handheld microphone with PTT built in connected in through the transceiver’s
microphone jack and into the Asymod III.
6- From an aftermarket handheld microphone with PTT built in connected in through the
transceiver’s microphone jack and into the Asymod III.
7- From an aftermarket pre amplified handheld microphone with PTT built in connected in through
the transceiver’s microphone jack and into the Asymod III.
8- From an aftermarket desk microphone with PTT built in connected in through the transceiver’s
microphone jack and into the Asymod III.
9- From an aftermarket pre amplified desk microphone with PTT built in connected in through the
transceiver’s microphone jack and into the Asymod III.
*When using the Asymod III, it is recommended to use a foot pedal or a modified PS/2 or USB mouse as
a momentary switch connected to the transceivers microphone jack as the PTT for more comfort and
ease of use.
Please refer to the Asymod III Operation & Troubleshooting Guide for operating and adjustment
instructions.
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Microphone installation via the transceiver’s microphone jack
In most cases, especially in stations operating at
higher RF output levels, when installing a
microphone via the transceiver’s microphone jack it
is recommended to install a 10uH inductor/RF choke
in series with the microphone audio line to block
possible RF interference if there is not one already
installed.
Most transceivers employ this method of RF filtering
close to the microphone inputs jacks, therefore,
depending on the transceiver, it is possible to
intercept the audio line by splicing the audio path to
the main PCB and tapping directly into the RF choke
coming from the transceiver’s audio input
microphone jack PCB. Look out for shunt caps that
might degrade audio frequency range.
Line / Mic in for a few transceivers can be seen
starting on FIG 7A. Note: all audio cables in the
installations should be shielded.
FIG 7A. The Cobra 29 does not have an audio input
RF filter choke. You may install one as shown.
Disconnect the wire connected to pin 2. Solder one
side of L1 to pin 2. Solder a shielded wire from the
other side of L1 and connect it to the Asymod +Line
In. Make sure to ground the shield to pin 1.
FIG 7B. The Cobra 25 has an audio input RF filter
choke L502. Disconnect the wire connected from
L502 to main board from the main board and
connect it to the Asymod +Line In.
FIG 7C. The Cobra 2000 and Texas Ranger have an
audio input RF filter choke L404. Disconnect the wire
connected from L404 to main board from the main
board and connect it to the Asymod +Line In.
FIG 7D –7F. Cobra, Galaxy, Super Star, Magnum, RCI-Ranger, CRE, etc.
Follow Fig. 7D to 7F for the rest of the configurations following the same guidelines used above.
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Installation Block Diagram
Installation for Other Transceivers
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NOTE:
IMPORTANT
Keep in mind that the transceiver is only the exciter and should not be expected to generate high levels
of RF power, it should be expected, however, to generate a clean, perfect modulated wide-band audio
signal that can be later amplified with a class C, RF power amplifier to the desired level. It is highly
recommended to use dual final transceiver which allow for plenty of headroom and much cooler
operation.
For single final transceivers, such as the Cobra 29s & 25s, Galaxy DX-2547, DX-919, DX-959, etc.,
both RF driver and RF final must be modulated to achieve maximum modulation. Typically a .75
watt carrier with peaks of 10 watts produces +300% modulation levels. This configuration puts a
greater load on the DC/DC converter as opposed to dual final transceivers where only the RF
driver is modulated.
For dual final transceivers (recommended), such as Galaxy DX-2527, DX- 98VHP, etc., only the
driver is modulated and the dual finals are fed +12 volts. This configuration offers plenty of
headroom and puts far less stress and less of a load on the DC/DC converter and allows for
higher RF output levels.
Cobra Section
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The Cobra 29 and 25 installation is straight forward and easy to do, simply follow the instructions in the
images below.
Cobra 25
Fig 7G
Cobra 29
Fig 7H
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Cobra 2000GTL
The Cobra 2000GTL is a multimode transceiver and there is the option to perform the basic or advanced
installation to keep SSB mode operable. Points 1 and 2 in Fig 7J are the insertion points TP7 and TP8.
If after the installation is complete, -100% modulation cannot be achieved, you can try lowering the
bias. If that doesn’t yield the results needed, unsolder L40 from the TR37 emitter side and solder it to
ground, then unsolder L43 from the VR9 side and solder it to ground. This will set the final RF stages at
class C bias.
Basic Installation
Fig 7J
Advanced Installation
Table of contents
