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Modifying a KPC-350BH Video Camera
for Manual Gain Control

The following modifications are those suggested by Sandy Bumgarner to provide a manual gain control on the KPC-350BH (= PC-164C) video camera.

Sandy writes:

The Side Mount and End Mount Chassis:

PC-164C modifications have been made in two form factors: The side mount and the end mount. The side mount minimizes the length of the modified camera and the end mount minimizes the diameter of the camera.

The side mount is essentially no longer than the PC-164C itself and will, at the F10 focal position, swing between the forks of an Alt-Az mounted Meade LX-90 (I have no experience with a 20 cm fork mounted Celestron yet. Mine is on a german equatorial mount, no problem with almost any length.). With a focal reducer in the optical path, it will not clear and if used above 70 degrees or so, it must be used with a diagonal or the LX-90 must be mounted on an equatorial wedge. It can't be helped, the PC-164C is essentially the limiting factor.

The end mount is for those who are not passionate about the length of the camera but care about the diameter. Those folks may have a Fastar Celestron and may want to put the modified PC-164C at the prime F2 focus of the telescope. I am such an individual and, since I have a german mount, I care about the diameter of the modified camera when I mount it on the FaStar.

Parts List: 

For the Modification (part numbers from DigiKey: www.digikey.com)

QTY	PART			NUMBER						$US
1 ea.	Project box
2 ea.	Setscrew, 4-40 X 1/4'	OSH						0.20
2 ea.	Nut, 4-40 X 5/16	DigiKey H216-ND/50				0.02
1 ea.	Knob			KILO International HD-75-3-6 (226-3030-ND)	6.48
1 ea.	Dial, paper		See picture
12 in.	Tubing, shrink, 1/8'	DigiKey A018C-4-ND/4				0.18
48 in.	Wire, wirewrap #30	DigiKey W7-ND/6					1.12
1 ea.	Pot, 5K linear		DigiKey RV6N502C-ND				7.93
1 ea.	Resistor, 1.5K ohm, 1/4 watt	DigiKey 1.50KXBK-ND/5			0.11
1 ea.	Resistor, 3.5K ohm, 1/4 watt	DigiKey 3.48KXBK-ND/5			0.11
1 ea.	Resistor, 10K ohm, 1/4 watt	DigiKey 10.0KXBK-ND/5			0.11
1 ea.	Diode, 1N4004 or equiv.	DigiKey 1N4004GICT-ND/10			0.04
1 ea.	Switch, DPDT, miniature	DigiKey 360-1065-ND				6.30
1 ea.	Switch, SPDT, miniature	DigiKey 360-1057-ND				4.20
1 ea.	LED, panel mounting	DigiKey 67-1190-ND				1.20
1 ea.	Jack, coaxial power, 2.1 mm	DigiKey SC1049-ND			2.92
1 ea.	Jack, RCA, yellow	DigiKey CP-1415-ND				0.71

For the Audio Enhancement (www.supercircuits.com)

1 ea.	Jack, RCA, red		DigiKey CP-1413-ND				0.71
1 ea.	Microphone assembly	Super Circuits PA-3				12.95

NOTE: I reccomend you add a microphone when you do the mods as it is very handy.  
      This mic is an excellent one.

For the Better Control Knob:

1 ea.	Control, 0 - 100 over 300'fb	KILO International 572-S-300		15.94
Note: this is a special order item, contact Kilo: www.kilointernational.com


Sandy's Note: 
I am sorry to supply the part numbers that are for me in the USA but equivalent parts will 
be available to you locally in the antipodes at electronic supply stores.

Final Axial and Lateral Units:



PC-164C First prototype:



PC-164C early chassis:



PC-164C w new chassis:



PC-164C modified circuit:



PC-164C Insides with wiring modifications:



PC-164C Exposed Pigtail:



Manual Gain Control Template:


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