CORRECTION: The B line does not have 4 pole crystal filters built-in. It has as single 8kHz (more or less)crystal filter in the front end. The bandwidths in the R-4/A/B is provided by a single L/C filter arrangement through switching of coupling and padding capacitors to increase or increase selectivity as needed. The same arrangement appears in the 2-B/C receivers as well as the SPR-4. While not as selective as selective as the R-4C, selectivity is nevertheless adequate for most casual CW operation.
The R-4C front end filter is not too broad as it is designed to provide sufficient bandwidths for proper operation of the noise blanker and passband tuner. If you narrow front end selectivity then the noise blanker becomes less effective and passband tuning becomes restricted. Yes you can narrow front end selectivity but there is no free lunch. Summary: as far as selectivity is concerned the B line is adequate but the C line has the potential to outperform the B line. There are other things to consider when choosing. If possible, get a copy of the C line reviews in QST which gives a good overall, if not technically thorough overview of features. Stay away from the so-called "Drake Mods" widely available on the web as it is not technically accurate. Sections of it are riddled with technically inaccurate conclusions and inaccuracies. Unfortunately they were included in the "Drake a Family Affair" book. The author of the book wanted to correct some of the errors but the author of the mods would only allow publication of his work without editing. Thus myths prevail. Makes great rading though. > Well, the C line is superior in selectivity, but mostly if it has been > modified, the first IF is too broad... ..there are mods to > improve audio and other areas, the C line had separate xtal filters > available where the B is four pole xtal filters and are built > in...filters are not cheap, INRAD has them but there around $100 each > or so. The B line is still my favorite... 73 Tim K8WBL > ---------------------------------------------------------------------- Submissions: [EMAIL PROTECTED] Subscribe: [EMAIL PROTECTED] - subscribe drakelist in body Unsubscribe: [EMAIL PROTECTED] - unsubscribe drakelist in body Hopelessly Lost: [EMAIL PROTECTED] - help in body of message Brought to you courtesy of TLCHost.net http://www.tlchost.net/ ----------------------------------------------------------------------
