[Hammarlund] Preselector suggestion?

[Carl]

----- Original Message ----- 
From: "Kenneth G. Gordon" <kgordon2006 at frontier.com>
To: <hammarlund at mailman.qth.net>
Sent: Tuesday, December 13, 2011 3:17 PM
Subject: Re: [Hammarlund] Preselector suggestion?


> On 13 Dec 2011 at 10:55, Brian Burns wrote:
>
>> As part of answers to my previous postings, several people have
>> mentioned getting improved performance by adding a preselector. Any
>> suggestions for particular ones? I'm not a purist, so solid state is
>> Ok by me too.
>
> I bought an old RME DB-20, which was even made in a military version,
> and used extensively by both hams and the military.
>
> However, I am sure there are better ones out there by now.
>
> One thing you might want to keep in mind though, at least concerning
> the SP-100 and SP-200 models: they come with "double-preselection"
> I.e., two RF stages.
>
> Adding a third (or even a fourth) RF stage one wouldn't hurt, I
> suppose. At least you would have absolutely no problem with images.
> :-)
>
> Ken W7EKB


The problem with all versions of the DB-20 are tubes that are noiser than 
58's, oir as noisy 6K7's, as what is in the radio and one stage full on at 
all times.

The DB-22A is the best and can easily be modified to replace the 6BA6's with 
better and also bypass one stage as 40db of gain is not needed. I have 2 of 
them fo use mainly on 30's sets.

The DB-23 is junk, broadband overload city.

I also have several Ameco and Palomars and do find those useful even on 
50-60's sets at times.

A HQ-145 would only benefit from a late SS version and only as far as 
sensitivity on the highest range.

Carl
KM1H