[Boatanchors] difference bet. 75A3 and A4?

[Garey Barrell]

Jim -

This is why I think the A-3 is the worst of the series.   The IF has 
been narrowed in "anticipation" of SSB, but the skirts are of course 
quite wide.   The result is a receiver that really isn't very good for 
AM  - OR  - SSB.

Same reason why the HQ-129X is a better AM receiver than the HQ-170.

73, Garey - K4OAH
Atlanta

Drake C-Line Service Manual
<http://www.k4oah.com>



Jim Wilhite wrote:

> Todd I recently picked up an A2 and have a question about it versus 
> the A1. In your answer to Gene, you stated the A1 had better audio 
> than the A2.
>
> I wonder to what the difference in the audio was attributed?  My A2 
> has had the IF section narrowed according to the book and is pretty 
> narrow compared to other receivers I own.  The manual for the A2 says 
> the conversion will produce 2.4 kc at 6 db down.
>
> That is equivalent to most transceivers of the late 60s and 70s 
> designed for SSB.  Needless to say, this makes any AM signal pretty 
> crappy, but converting to broadband  gives 4 kc at 6 db.
>
> Anyway, I don't have an A1 manual to look at and am curious from 
> someone that knows.  Might it be a good thing to remove the narrow 
> band conversion and look at converting the audio section to resemble 
> the A1?
>
> 73  Jim
> W5JO
> .
>
>>
>> Eugene -
>>
>> Let's see if this one makes it to the list, my last post about Beckman
>> was bounced back.
>>
>> The mechanical filters actually work only to narrow things in noisey
>> conditions. The 75A-4 actually has a product detector for SSB
>> reception. While the A-2 and A-3 are basically identical (except the
>> A-3 having 2 mechanical filters which could be retrofit to the A-2),
>> the A-4 is a 'new' receiver in comparison. The main difference is that
>> the 75A-4 was designed for SSB operation with the associated
>> refinements. Even the cabinet design is completely different, with the
>> A-4 cabinet being made up of several pieces including the front panel.
>>
>> If you want a more traditional AM/CW receiver, stick with the A-3 or
>> even get the A-2 and avoid the mechanical filters altogether. If you
>> want the SSB option along with reasonably decent AM and CW with the
>> ability to narrow things down to 500cps (with CW filter), the 75A-4 is
>> tough to beat. And although 6kcs was the best you could do for AM,
>> there is now an aftermarket filter available for 9kcs to broaden
>> things out a bit more. You can tune SSB with the A-3, but not as
>> easily. And there's also the passband tuning system on the A-4, which
>> is very ingenious and fun to play with.
>>
>> As far as price, a 75A-4 will set you back at least twice as much as
>> the earlier models if you shop online, depending on condition and
>> optional filters installed.
>>
>> My choice would be for the 75A-1 with its nifty band-in-use lighted
>> dial and very good audio. Tunes SSB amazing well too even though it
>> has no prod det. Doesn't cover 160, though.
>>
>> de Todd/'Boomer'  KA1KAQ
>