Ramsey Electronics AA7 用户手册

下载
页码 16
AA7 
  14 
Unusual oscillations in receiver:  Some portable receivers not enclosed in 
metal cases may break into oscillation when connected to any RF 
preamplifier. Try reducing the AA7 gain control and make sure good  
grounds are on the interconnecting coax cables. 
 
Receiver overloading, heterodynes, images:  A preamplifier will intensify 
any problems with selectivity and image rejection due to poor receiver 
design. 
 
ACTIVE ANTENNA COMPARISONS 
 
   The author of this AA7 instruction manual has conducted extensive side-
by-side comparisons of the AA7 with the Heathkit HD-1424 and MFJ 
Enterprises, Inc. Model 1020A active antennas, both of which have band-
switched tunable preamplifiers as well as an understandably higher selling 
price. If all three units are compared, each using only its on-board whip 
extended to equal heights, the two tunable units do produce a stronger 
signal. We would hope so!  However, attaching about two more feet of wire 
to the AA7's whip resulted in it delivering the strongest signal. Similarly, 
increasing the antenna lengths of the other units resulted in increased signal 
strength. It becomes a question of how much you wish to pay for the shortest 
possible indoor antenna! The AA7's  competition performs well, but we are 
sure you will appreciate the AA7's versatility and budget pricing. 
 
THE AA7'S ENCLOSURE: THE FINISHING TOUCH 
 
   The Ramsey Electronics custom case, panel and knob kit is optional for 
the AA7 as it is for all of our standard major PC-board kits.  In it’s case, the 
finished AA7 will be attractive and virtually indestructible, so that the world of 
radio can be at your fingertips wherever you go. Use of our factory enclosure 
also enhances the resale value of your AA7. 
 
A FINAL SUGGESTION 
 
   A small antenna is most effective whenever it can be outdoors and clear of 
any surrounding metal building structure. You may wish to use a mix of 
personal ingenuity and hardware store/junk-box parts to make a simple 
remote whip that can be quickly mounted on windows, windowsills, balcony 
rails, or handy points on cars, RVs, etc. We hope you will enjoy your AA7 in 
a wide variety of listening and monitoring situations. 
Kit building is FUN!  Ramsey has a wide variety of nifty kits.  Ask for our free 
catalog, where there are plenty more kits ideally suited for you!