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Weak Signal VHF by Tim Marek - K7XC
10 Ghz Whitebox Conversion Notes

by Tim Marek - K7XC

Important 10Ghz White Box Specifications
The Maximum 146 Mhz IF Drive Level is -20 Dbm.
Depending on tuning, you should expect between 80 and 300 MW output at 10 Ghz.
After tuning the stock receiver has a 10 / 11 dB noise figure, easily remedied with the use of an outboard Preamp.

With the original crystal in the LO (High side injection), typically 146.100 mhz = 10368.100 Ghz, but not always. The unit I purchased on Ebay was 33 mhz low. With the original crystal in the LO, It is an inverting transverter - LSB at 2M = USB on 10 Ghz, Tuning down in frequency on 2M = tuning up in frequency on 10Ghz, etc.

Replacing the LO xtal with one for 106.5 Mhz (low side injection) will move the IF frequency from 146.100 Mhz to 144.100 Mhz and will allow the unit to operate as a non-inverting transverter making operation of the finished unit much easier. USB on 144 Mhz remains USB on 10GHz and Tuning down in frequency on 2M tunes down on 10Ghz as well. The xtal is a 1ppm, HC36U type, rated for an oven temperature of 70 degs C. When ordering a new xtal, It is a good idea that the original MA/Comm xtal be included so the manufacturer can check its characteristics to ensure that the replacement is identical electrically.

White Box Power Supply and Control Circuitry
Basically there are 6 or 7 circuits you need to fabricate, depending on your particular pile of surplus parts. As I read the three conversion articles, it was clear to me that the WA6CGR control circuitry, The G3PHO +20V supply, and the FEBO -5V Supply were the way to go. I researched Digikey and Newark Electronics for all the needed parts and the determining factor on which to use was based on the need for VERY LOW ESR Filter caps and Newark carries the Sanyo OS-CON Series that the Maxim data sheet recommended. A list of links to the various web sites mentioned and a complete parts list is available at the end of this document.

Regulated Portable Power Supplies To Operate The White Box On +12V Systems
The White box needs +20V DC to run the LO. This supply needs to be clean, stable, and well regulated. The RF Unit requires +12V DC to operate the RX and TX sections along with -5V DC used to bias the output stages of the 10 Ghz Transmitter. It is important that the bias voltage be applied before ANY other voltages or the transistors in the final amplifier will be destroyed.

After researching all the data available on the web, I elected NOT to build the WA6CGR Regulated power supply based on the LM-383T, 7905, and 78M18 devices. The Febo document compares this design and the circuit suggested by G3PHO based on an LM2577 Step Up Regulator. He describes how the LM383T circuit runs hot (well under 50% efficient) and is full of high frequency noise whereas the LM2577 runs cold at near 90% efficiency with a fairly clean output. After building it for myself I concur that the LM2577 design is the best way to go. I built a second LM2577 supply to run the surplus +28V SMA Coaxial relays and added a 3rd SPDT relay to the T/R sequencer to switch the 28V needed to drive them.

This left me without a -5V bias supply as the "CGR" design covered all the needed voltages. I looked into the G3PHO design using an ICL7660 Voltage Inverter chip to turn +5V DC into -5V DC. The unit is rated at 20ma max output which after reading the Febo documents proves to be well below the 90 ma needed. He suggests using a Maxim MAX764 DC-DC converter chip, which can provide up to 300ma at -5V from a +12V source.

While the Febo document doesn't provide a schematic diagram of the circuit, the Maxim data sheet (available on their web site) provides all the info you need to design one of your own. A note of caution, the 8pin chip for the
-5V version is usualy only available in surface mount configuration in small quantities whereas the -12V and -15V versions are readily available in 8pin DIP. Any of the 3 units will work, as all versions provide means for an adjustable output in addition to their fixed voltage configuration. As I am a relative novice at soldering small surface mount devices, I chose to use the MAX765 (-12V) regulator with an outboard divider network to set the
-5V output. This allowed me the flexibility to use a standard 8pin DIP chip socket. While The MAX765 is easier to work with, it will provide only 150ma at -5V but that is more than enough for this application. The resistor divider network values needed to obtain -5V output are: R1=150K, and R2 = 500K. I used 1/4W 5% tolerance resistors and the output was -4.95 volts with 14V input.

White Box Control Circuitry
All the +12V DC power is channeled through a 3 amp fuse, an input filter network, a 5amp SPST ON/Off switch with a green "Power" LED indicator. That in turn is fed to the +28V, +20V and -5V Power Supplies and the T/R sequencer/control circuit.

The T/R sequencer/control circuit energizes the +12V RX or +12V TX lines to the RF Unit, the +28V to the RF Coaxial relays on TX, and incorporates a 50 ms delay switching on the +12V TX line while providing for a -5V interlock to prevent final amplifier damage. To accomplish this task requires 3 circuits, a +12V PTT/Relay Driver, A 28V Coaxial Relay Control, and a TX/RX Control. This is all accomplished with the use of Three SPDT 12V DC relays, three transistors and a handful of resistors and diodes.

The use of colored LED indicators on the front panel provides quick status indication of the system. "Green" indicates +12V "Power", "Yellow" indicates "VCO Lock", "Red" Indicates "TX", "Orange" Indicates "RX".

A 1ma meter movement provides an indication of the RF Unit's relative power output. I am researching a circuit to drive an LED bar graph display instead.

On each power supply board and the 12V Power Input Filter are LED Power indicators as well.

White Box T/R Sequence Info
This assumes that the natural resting state of the finished White Box 10 Ghz System is in the RX mode with all control relays in their NC position.

To Transition from RX to TX, The following events must occur in the order as shown.
1) Switch ANT from PREAMP IN to PA OUT (Or Jumper if No PA)
2) Switch RF UNIT SMA From PREAMP OUT to PA IN (Or Jumper if No PA)
3) Switch IF From RX IF OUT to TX IF IN (If Split IF Port Are Not Used)
4) 50ms later, switch +12V from RX 12V to TX 12V On RF Unit.

To Accomplish this the control circuits are engaged in the following order
1) +12V PTT/Relay Driver Circuit
2) 28V Coaxial Relay Transfer Circuit
3) RF Unit RX/TX +12V Switch Circuit, with -5V Interlock and 50ms delay

Lifting the GND triggering the PTT/Relay Driver Circuit returns the Unit back to RX mode.

Wire Color Codes To/From The T/R Sequencer
Red, Solid - +12V Input
Red, With White Stripe - +12V RX on RF Unit
Red, With Black Stripe - +12V TX on RF Unit
Black, Solid - Ground For +12V
Black, With White Stripe - Ground for +28V, +20V, & -5V Power Supplies
Orange, Solid - +28V Feed From Power Supply To Sequencer
Orange, With Black Stripe - From Sequencer to +28V Coaxial Relays
Green, Solid - -5v Bias & Sequencer Bias Voltage Interlock

Parts Lists - Unless Noted All Resistors Are 1/4W Rating. (All Part #s Are For Newark Electronics)

+20V LO Supply - Neat & Easy +20V PSU - G3PHO Website
(1) LM2577T-ADJ Step up Voltage Regulator
(1) 220uf 25VW Low ESR Electrolytic
(1) 470uf 35VW Low ESR Electrolytic
(1) 0.1 uf ceramic
(1) 0.47uf ceramic
(1) 100uh Inductor, Maplin #AH32K type,
(1) 1n5822 Schottky Diode,
(1) 1K, 1/4W, Trimpot
(1) 2.7K
(1) 2K
(1) 38.4K

-5V Bias Supply - Pg #9 FEBO Document
(1) MAX765CPA #79C2352
(1) 47uh Coil #98B8447
(1) 1n5818 Diode #09F4475
(1) 68 uf Os-Con #20C2899
(1) 120 uf Os-Con #20C2908
(2) 0.1uf ceramic #81F2061

Control Circuitry - Pg #19 WA6CGR Document
(2) MPS-A55 PNP Transistors #38C7542
(2) 2n2222a NPN Transistors #07F9651
(4) In4148 Diodes #95B4971
(2) "Red" LEDs #33C1318
(2) "Yellow" LEDs #33C1343
(2) DPDT relay, 12V, 8A contacts #94B9819
(1) 20K Trimpot, W #67F5748
(4) 4.7K, 5% Junkbox
(2) 10K, 5% Junkbox
(1) 22K, 5% Junkbox
(1) 0-1 ma Meter, 1 " Sq, (OPTIONAL) #62F3541

12V Input- Power Filter/Control - Pg #20 WA6CGR Document
(1) 3amp Fuse, Glass, Junkbox
(1) Panel Mount Fuse Holder Junkbox
(1) 50uh, 10A choke #98B8447
(1) 50V 10A Diode #18C4420
(1) 2200 uf 25vw Electrolytic Cap #91F6280
(1) "Green" Led, T1 size #33C1272
(1) SPST Switch, 5amp contacts #50N265
(1) 1K Junkbox

2M Xvcr Interface - Pg #13 WA6CGR Document
(3) 1n4148 Diodes, #95B4791
(1) 12V DC DPDT Relay, 8A Contacts #94B9819
(1) 10K Trimpot, W #67F5709
(2) 150 Ohm Junkbox
(1) 100 Ohm Junkbox
(1) 50 Ohm, 40W Load Junkbox

LO AFC Bias Control - Pg #4 FEBO document
(1) 12V Zener Diode, 1W #95B4978
(1) 10K Trimpot, W #67F5709
(1) 22uh inductor #78F2200

LO Enhancements - Pg #5 FEBO Document
(1) 15V Zener Diode, 1W #95B4979
(1) 1.0 UF, 50v Tantalum #95F7181
(1) 330 Ohm Junkbox

Microwave Referance Material
G3PHO - "10Ghz White Box Modifications"
WA6CGR - "A Complete X-Band SSB Portable Communications System",
FEBO Geekworks - "10Ghz White Box Conversion Notes",
San Bernardino Microwave Society,
North Texas Microwave Society,
San Diego Microwave Group,
North East Weak Signal Society,
Western States Weak Signal Society,
UK Microwavers,
Microwave Update,
50Mhz and Up group,
Microwave Journal,
US Microwave,
Angle Linear,
Cactus Connection,

10GHz Whitebox Conversion Notes by Tim - K7XC
Updated 12/15/05