Make any changes or corrections to the data fields. When finished, click on the UPDATE button.
Author
Callsign
Email
Security (anti-spam) Question: How many dits in 72?
Dits
Description
Record #
27
RevDate
Sun, 31 Jul 2011 20:04:34 -0500
Details
This is a prototype of a simple BJT IF amplifier which has variable gain. It was adapted from a design in Chapter 6 of EMRFD. LTSpice says the gain is about 25 dB running wide open, with an adjustable range of about 30 dB. The original design calls for proper PIN diodes for D1 and D2, but the 1N4007 is a well-known ``fake`` PIN diode and will work in this application. This may not be enough amplification for my IF stage, so another amp stage before this one may be coming. More to come when I build the circuit. -Jason, NT7S 13 Dec 2006 Playing with LTSpice has showed me that the input return loss is horrible (thanks for the tip Soldersmoke). Some further investigations are in order to resolve this problem. - Jason, NT7S 15 Dec 2006 Another amplifier stage has been added, along with a 4 dB attenuator between stages to help the input return loss to the second stage. An L-network was added to the input of the circuit to match the 220 ohm Zout of the crystal filter to the 50 ohm input of the amplifier. The input return loss is much improved at 4.9152 MHz. - Jason, NT7S 24 Dec 2006.
Schematic=
NT7S_IF_Amp.gif
AuxFile=
NT7S_IF_Amp.zip
Return to SEARCH
Please use unique filenames that include your callsign. Existing files will be overwritten
The Schematic file must be a GIF or JPG. The Auxfile must be a ZIP
Replace Schematic
Replace AuxFile
Return to SEARCH