[Repeater-Builder] Re: Amateur Radio - excessive gain by design

[skipp025]

Well... to sell radios to Amateurs most mfgrs promise the moon and try 
to build it into the radio. Most hams use radios in locations where 
the excessive gain is desired (ie not on a mountain top). So a user 
outside most metro - busy areas really loves the red hot receiver.

In a mountain top location... some of the old thick and numb but well 
filtered radios like the Micor or GE Master Pro Receivers would be 
better suited. 

Hey you GE guys... is the Mater II series as well filtered as the 
earlier Master Pro stuff? 

Your remote base Kenwood radio gain problem sounds just like the 
same problem I had with my Yaesu Moutain Top Radio. They are after 
all made for typical Amateur Ham Radio service. 

cheers, 
skipp 

 I did; it was.  I was able to tame the problem somewhat by reducing 
 the 1st IF gain somewhat, resulting in significantly mitigating the 
 adjacent channel squelch problem while losing maybe a dB or two at 
 most in sensitivity.  IMO, a combination of too much IF gain  
 defective or not enough 1st IF filtering.


   Also had problems with the IF filtering, causing the squelch to
   close on reasonably strong signals when a strong signal 15 kHz
   away was present.
 
  I'm not sure if I'd blame the IF section for the trouble unless 
  I did a lot of testing.
 

Re: [Repeater-Builder] Re: Amateur Radio - excessive gain by design

[Jim B.]

skipp025 wrote:
 Well... to sell radios to Amateurs most mfgrs promise the moon and try 
 to build it into the radio. Most hams use radios in locations where 
 the excessive gain is desired (ie not on a mountain top). So a user 
 outside most metro - busy areas really loves the red hot receiver.
 
 In a mountain top location... some of the old thick and numb but well 
 filtered radios like the Micor or GE Master Pro Receivers would be 
 better suited. 
 
 Hey you GE guys... is the Mater II series as well filtered as the 
 earlier Master Pro stuff? 
 
 Your remote base Kenwood radio gain problem sounds just like the 
 same problem I had with my Yaesu Moutain Top Radio. They are after 
 all made for typical Amateur Ham Radio service. 
 
 cheers, 
 skipp 
 
 I did; it was.  I was able to tame the problem somewhat by reducing 
 the 1st IF gain somewhat, resulting in significantly mitigating the 
 adjacent channel squelch problem while losing maybe a dB or two at 
 most in sensitivity.  IMO, a combination of too much IF gain  
 defective or not enough 1st IF filtering.

One of the problems I've noted with many made-for-ham mobiles is 
actually a lack of low-IF gain, causing the limiter to not go into 
saturation fully, which makes the rx subject to noise. I think for the 
most part they are getting the excessive gain in the front end, which 
makes it more susceptable to IMD, front end overload, and all that other 
junk.

-- 
Jim Barbour
WD8CHL