Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!zaphod.mps.ohio-state.edu!uakari.primate.wisc.edu!aplcen!boingo.med.jhu.edu!haven.umd.edu!wam.umd.edu!rustyh From: rustyh@wam.umd.edu (Michael Katzmann) Newsgroups: sci.electronics Subject: Re: WANTED: A crystal AM HF recvr, and "one antenna -> 2 recvrs" Message-ID: <1991Jun1.143029.11055@wam.umd.edu> Date: 1 Jun 91 14:30:29 GMT References: Sender: usenet@wam.umd.edu (USENET Posting) Organization: University of Maryland at College Park Lines: 39 Nntp-Posting-Host: epsl In article mrapple@quack.sac.ca.us (Nick Sayer) writes: >I am using a Sony ICF-2010 and a homebrew modem to receive and decode >CHU. It's a bit of a waste to use such a fine radio for something >so simple. So... > >1. Is there a cookbook circuit for a crystal controlled single >conversion superhet? It'd be nice if it were frequency switchable >in a simple way. Even better if it were TTL frequency switchable. This looks like a good application for a converter. i.e. ---RF AMP-----Mixer----1600khz filter----MF AM Receiver Xtal | Oscill--| Schematics of these are published regularly. It's cheap, its results in dual conversion superhet, it's alot easier to build up than a a full receiver (for the novice at least). The choice of 1600 kHz for the "1st IF" is of course flexable (just choose something away from any strong local AM stations.). > >2. I want to hook one antenna to 2 (or 3, or 4.....) receivers. >And no, a switch won't do. I would like them all to work AT THE SAME >TIME. Is this simple to do? > A pre-amp with sufficient gain and a splitter is all you need. If you just use a splitter (say for two receivers), your noise figure will degrade by the splitter loss (say 3-4dB) but if you use a pre-amp then the noise figure is that of the pre-amp plus your splitter loss divided by the gain of that first pre-amp. So as long as you have enough gain that splitter loss will not hurt the S/N ratio, you are in good shape. -- Michael Katzmann (VK2BEA/G4NYV/NV3Z) Please email to this address | Broadcast Sports Technology | 2135 Espey Ct. #4 \|/ Crofton MD 21114-2442 (301) 721-5151 ...uunet!opel!vk2bea!michael