[Hallicrafters] SR-2000

[lardiere at ix.netcom.com]

Jim,

My SR 2000 has a somewhat different gain issue.  10 meter segments are a bit less sensitive than the other bands.  On 80-20, 100 uV yields S9.  If anything, 15 is the hottest of them all; 50 uV yields S9 easily, which is what you describe as normal.  10 is down 1/2 S unit (100 uV = s 8.5).  TX drive is down commensurately.  I have spent a lot of time on the alignment, tubes, and component/voltage checks.  Tuned circuits seem to behave as expected on all bands.   IF alignment was as expected after replacing a few bad caps and resistors. 

Any idea how 15 could be hotter than the others?  Your thoughts on the inadvertent 20-m coupling are interesting, but I don't see how 10 would be affected.  And it's a real puzzler why 15 would have more drive.  Have not found that on any Hallicrafters (or anything else, for that matter).

This SR 2000 is on the bench after a lot of work over the last two months.  Seems to work pretty well, but also having a tough time getting over 350 W on CW (low voltage).  Seems to be too much AALC - 10 o'clock on the TX audio results in plenty of AALC meter action.  Max power out is constant for all bands with expected currents.  AALC tube voltages are now pretty close to the manual values.  Might be the finals - have not tried a known good set, yet.

73,

Rocco N6KN  
-----Original Message-----
>From: Jim Liles <james.liles at comcast.net>
>Sent: Dec 12, 2006 8:25 AM
>To: hallicrafters at mailman.qth.net
>Subject: [Hallicrafters] SR-2000
>
>Good morning Jerry:
>Congratulations on the SR-2000 acquisition.  The SR-2000 should be capable 
>of moving the S-Meter to S5 with a 3uv signal and S1 with 1uv and S9 with 
>50uv.  Also, you should be able to distinguish a two tone .05 uv signal.  If 
>you can clearly distinguish a .1uv two tone or carrier and sidebands on an 
>AM signal, look at the S-Meter tube and circuitry otherwise start at the 
>6.5MHz IF strip.  T1 and T2 cannot be adjusted without a sweeper --- tried 
>and wore the slugs out.  If you have a problem with the 15 meter band, there 
>is a design booboo that may be present.  The 20 meter coils for the in and 
>out of the first rf amp resonate in  or very close to 21MHz when switched to 
>any other band than 20 meters.  Also, being directly adjacent and 
>unshielded, couples to the 15 meter coil and imparts resistance to the 15 
>meter tank --- the grid dip effect.  For some strange reason, they fixed the 
>problem in the 12BY7 final drive circuits (18pf rather than 47pf) but forgot 
>the other two.  One other question, can you overdrive the finals in tune 
>mode?  --- Kindest regards Jim K9AXN
>
. . .