[Hammarlund] HQ-200 Low Sensitivity

[Singley, Rodger]

Bill,

The first thing to suspect on any of the Hammarlund HQ series with a 6C4 HFO is the tube.  You may need to try several to find one that works well in the receiver and putting in a brand new tube is no guarantee that this is the "best" tube for the receiver.  Low HFO injection will greatly reduce mixer gain and typically problems with the 6C4 are more prevalent as the frequency increases.  The 6BE6 may also be contributing to the problem but the 6C4 is always a prime suspect in Hammarlund receivers.  Your HQ-100 may have the same problem.

Rodger WQ9E


-----Original Message-----
From: hammarlund-bounces at mailman.qth.net on behalf of Bill Stewart
Sent: Thu 9/16/2010 7:54 AM
To: hammarlund
Subject: [Hammarlund] HQ-200 Low Sensitivity
 


I recently acquired an HQ-200, which is sensitive on all bands except the 10-30 mhz range. For example, WWV is S-9 at 10 mhz on the 4-10 mhz range but only about S-3 at 10 mhz on the 10-30 mhz range. It is more sensitive in the mid-range area, say 12-21 mhz, with some SWBC stns reading well over S-9. Generally, the sensitivity seems to be real low at both ends of the 10-30 range. The 20BS range seems to be fairly sensitive. I have gone thru the alignment and only minor adjustments were needed for peak readings. The IF is on the high side per the aux. rcvr.  A while back I had a similar problem with a HQ-100, which we discussed here...but in that case I temporarily shelved it due to a stuck slug. It also had low sensitivity on the 10-30 mhz range. Is this normal for the HQ-200/100 rcvrs. Is anyone using a HQ-200 and can tell me how the sensitivity is on the 10-30 range? 



I also noticed, that there are some differences in my rcvr from the BAMA schematic (the BAMA info is issue 1 of the manual). A couple noticed are tandem pots on the sensitivity control and a piece of coax going from the ant. trimmer capacitor to the main tuning capacitor. These two items don't show up on the BAMA pix. Does anyone have a schematic they could send me that would fit my rcvr (s/n 36031666). 



Any help would be greatly appreciated. Thanks..73 de Bill K4JYS 




 
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