G0MJW Bias-T and reference-injection boards - Revision history

M0JUR: Link bills of materials, add note about the geometry and allowed dimensions of the LNB connector, remove the "work in progress" warning

2023-01-31T10:00:18Z

Link bills of materials, add note about the geometry and allowed dimensions of the LNB connector, remove the "work in progress" warning

M0JUR: Note on TCXO soldering as per CQ-TV 266

2023-01-30T23:21:34Z

Note on TCXO soldering as per CQ-TV 266

M0JUR: Specify attenuation of both IF and reference attenuators in the case of them having been built using resistors specified on the schematics

2023-01-30T23:15:49Z

Specify attenuation of both IF and reference attenuators in the case of them having been built using resistors specified on the schematics

M0JUR: Add some content

2023-01-30T11:52:01Z

Add some content

M0JUR: Stub

2023-01-29T11:52:34Z

Stub

New page

WORK IN PROGRESS! I am about to put on this page the schematics of, bills of materials for etc. for the two boards for which the BATC Shop has PCBs.

@@ Line 1: / Line 1: @@
 For those among us who would like to feed external frequency reference to their LNBs, Mike G0MJW has designed two boards which combine the usual Bias-T with the ability to send the reference signal on the same feeder. This of course means having to adapt the LNB accordingly - but given you will likely have to modify it to accept external frequency reference in the first place, it shouldn't be a problem.
 Both boards feature pads for Pi attenuators on both IF and reference lines, with resistor values as shown in the schematics providing 10dB attenuation on the former and 3dB attenuation on the latter. These can be omitted if not necessary, modified should different attenuation be desired, or possibly replaced with Pi filters.
 == External reference ==
@@ Line 10: / Line 14: @@
 [[File:G0MJW_bias-ext_ref-schematics.png|800px]] [[File:G0MJW_bias-ext_ref-model.png|800px]]
 A blank PCB for this project is available from [https://batc.org.uk/shop/lnb-bias-t-and-reference-injection-blank-pcb/ the BATC Shop].
 Inductor pads can accommodate a wide range of different packages, both SMD and through-hole ones.
 To omit attenuator on ''IF out'': replace R3 with a 0 Ohm jumper or a solder bridge, omit R1+R5.
@@ Line 24: / Line 30: @@
 [[File:G0MJW_bias-int_ref-schematics.jpg|800px]] [[File:G0MJW_bias-int_ref-model.jpg|800px]]
 A blank PCB for this project is available from [https://batc.org.uk/shop/lnb-reference-bias-t-and-diplexer-blank-pcb/ the BATC Shop].

← Older revision		Revision as of 23:21, 30 January 2023
Line 26:		Line 26:

	A blank PCB for this project is available from [https://batc.org.uk/shop/lnb-reference-bias-t-and-diplexer-blank-pcb/ the BATC Shop].		A blank PCB for this project is available from [https://batc.org.uk/shop/lnb-reference-bias-t-and-diplexer-blank-pcb/ the BATC Shop].
		+
		+	The TCXO has all the pads underneath and is therefore suggested to be fitted first, tinning the pads and with hot air or a hotplate.

	C3 can be fitted as needed to tune the crystal filter. For the crystals specified in the BoM it shouldn't be necessary.		C3 can be fitted as needed to tune the crystal filter. For the crystals specified in the BoM it shouldn't be necessary.

@@ Line 1: / Line 1: @@
 WORK IN PROGRESS! Still needs the BoMs, and possibly some reformatting.
-For those among us who would like to feed external frequency reference to their LNBs, Mike G0MJW has designed two boards which combine the usual Bias-T with the ability to send the reference signal on the same feeder. This of course means having to modify the LNB accordingly - but given you will likely have to modify it to accept external frequency reference in the first place, it shouldn't be a problem.
+For those among us who would like to feed external frequency reference to their LNBs, Mike G0MJW has designed two boards which combine the usual Bias-T with the ability to send the reference signal on the same feeder. This of course means having to adapt the LNB accordingly - but given you will likely have to modify it to accept external frequency reference in the first place, it shouldn't be a problem.
-Both boards feature Pi attenuators on both RX and reference lines. These can be omitted if not necessary, or possibly replaced with Pi filters.
+Both boards feature pads for Pi attenuators on both IF and reference lines, with resistor values as shown in the schematics providing 10dB attenuation on the former and 3dB attenuation on the latter. These can be omitted if not necessary, modified should different attenuation be desired, or possibly replaced with Pi filters.
 == External reference ==

← Older revision		Revision as of 11:52, 30 January 2023
Line 1:		Line 1:
−	WORK IN PROGRESS! ~~I am about~~ to ~~put~~ on ~~this page~~ the ~~schematics~~ of, ~~bills of materials~~ for ~~etc~~. ~~for~~ the ~~two boards~~ for ~~which~~ the BATC Shop ~~has PCBs~~.	+	WORK IN PROGRESS! Still needs the BoMs, and possibly some reformatting.
		+
		+	For those among us who would like to feed external frequency reference to their LNBs, Mike G0MJW has designed two boards which combine the usual Bias-T with the ability to send the reference signal on the same feeder. This of course means having to modify the LNB accordingly - but given you will likely have to modify it to accept external frequency reference in the first place, it shouldn't be a problem.
		+
		+	Both boards feature Pi attenuators on both RX and reference lines. These can be omitted if not necessary, or possibly replaced with Pi filters.
		+
		+	== External reference ==
		+
		+	Described in CQ-TV 263. Useful if you have a stable 25MHz reference source such as a GPSDO.
		+
		+	[[File:G0MJW_bias-ext_ref-schematics.png\|800px]] [[File:G0MJW_bias-ext_ref-model.png\|800px]]
		+
		+	A blank PCB for this project is available from [https://batc.org.uk/shop/lnb-bias-t-and-reference-injection-blank-pcb/ the BATC Shop].
		+
		+	Inductor pads can accommodate a wide range of different packages, both SMD and through-hole ones.
		+
		+	To omit attenuator on ''IF out'': replace R3 with a 0 Ohm jumper or a solder bridge, omit R1+R5.
		+
		+	To omit attenuator on ''Ref in'': replace R4 with a 0 Ohm jumper or a solder bridge, omit R2+R6.
		+
		+	== Onboard reference ==
		+
		+	Described in CQ-TV 266.
		+
		+	[[File:G0MJW_bias-int_ref-schematics.jpg\|800px]] [[File:G0MJW_bias-int_ref-model.jpg\|800px]]
		+
		+	A blank PCB for this project is available from [https://batc.org.uk/shop/lnb-reference-bias-t-and-diplexer-blank-pcb/ the BATC Shop].
		+
		+	C3 can be fitted as needed to tune the crystal filter. For the crystals specified in the BoM it shouldn't be necessary.
		+
		+	To omit attenuator on ''IF out'': replace R13 with a 0 Ohm jumper or a solder bridge, omit R11+R15.
		+
		+	To omit attenuator on TCXO reference: replace R14 with a 0 Ohm jumper or a solder bridge, omit R12+R16.