[Hammarlund] HQ-145 misprint or what?

[Richard Knoppow]

----- Original Message ----- 
From: "Bob Camp" <ham at kb8tq.com>
To: "GARY BROWN" <XFRMRS at ROADRUNNER.COM>
Cc: "Hammarlund QTH LIST" <hammarlund at mailman.qth.net>
Sent: Sunday, March 23, 2014 5:32 AM
Subject: Re: [Hammarlund] HQ-145 misprint or what?


Hi

These radios were done by hand. Early in the production 
process, they probably did not have all the “normal 
 mistakes” cataloged for the inspectors. What you have is a 
prime example of how a test escape trashes the company’s 
reputation rather than getting fixed in the field.

Bob

On Mar 23, 2014, at 8:18 AM, GARY BROWN 
<XFRMRS at ROADRUNNER.COM> wrote:

> I have an HQ-145 on the bench that belongs to a friend of 
> mine. His complaint was it was never a good receiver. He 
> has had it from day one but just recently brought it out 
> of the closet after all these years.
>    Here is the problem. The original manual says a 6.8 meg 
> resistor from pin #6 to pin #7 on V-4 (6BA6), IF amp. I am 
> looking at this resistor and its across pin #1 to pin #7. 
> BUT, get this, The original diagram shows a 2.2k (R-44) 
> from pin #1 of this same tube where the one I have is 
> 470K. Now, the resistor from Pin #6 shows 470k on the 
> diagram but mine is 2.2k. Looks like these resistors were 
> reversed for some reason. Doesn't look like any one has 
> ever touched them. As for the rest of the circuits, its 
> the same as the original manual diagram.
> Now, my question. Were there production changes made to 
> the IF amp? If not, do you think these resistors were 
> wired wrong at the factory.
> Regards,
> Gary

     A little more. I think the 6.8meg resistor belongs as 
shown in the BAMA manual, that is from cathode to grid or 
pin-1 to pin-7.  Its purpose evidently has to do with the 
manual RF gain. If it goes from pin-6 to pin-7 it puts some 
positive voltage on the cathode from the screen grid.  I 
can't see why this would be done. Note that the S meter 
measures the difference between the cathode current of V-4, 
which is on the AVC bus and V-5 which has fixed bias and 
will have pretty constant cathode current. So, anything that 
affects the current of V-4 will affect the way the S meter 
reads.  Have a look at the BAMA manual and compare it to 
what you have. I am pretty sure there are other, higher 
resolution, manuals on the web.
     Again, 2.2K is probably the right value for the 
resistor to the screen grid at pin-6 and 470K the right 
value for the control grid resistor to pin-1.


--
Richard Knoppow
Los Angeles
WB6KBL
dickburk at ix.netcom.com