[Hammarlund] HQ-145 misprint or what?

[Richard Knoppow]

----- Original Message ----- 
From: "GARY BROWN" <XFRMRS at ROADRUNNER.COM>
To: "Hammarlund QTH LIST" <hammarlund at mailman.qth.net>
Sent: Sunday, March 23, 2014 5:18 AM
Subject: [Hammarlund] HQ-145 misprint or what?


>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
>
    I may be confusing what you are saying above. I am 
looking at the schematic of the handbook from BAMA.  The 
6.8meg resistor goes between the grid and cathode of V-4, 
that is pin-1 to pin-7.  I am not quite sure of the purpose 
of this resistor.  There is a 470K resistor from pin-1 to 
the AVC bus at C-18, this is a decoupling resistor for the 
AVC.  There is a 2.2K resistor from pin-6 to the screen grid 
voltage source decoupled by C-68 (hard to read this diagram) 
at pin-6. If your receiver had these reversed it would have 
effectively cut off the tube because the screen grid voltage 
would have been very low and the control grid effectively 
shorted.  There is a tube base voltage chart in the 
handbook, double check to see that the voltages are about 
right.
    If there was a wiring error from the factory it would 
pay to check for others.


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