[Hammarlund] Serial Numbers

[Richard Knoppow]

----- Original Message ----- 
From: "robert bartlett" <robert.b at telus.net>
To: <hammarlund at mailman.qth.net>
Sent: Wednesday, January 26, 2011 4:15 PM
Subject: [Hammarlund] Serial Numbers


> Hi all,.... new to this forum.  Just acquired a Hammerlund 
> H129X  in working order.  Will replace all the caps soon. 
> Does anyone have an idea how to read the serial 
> numbers,..........this one reads 9349.  What pit falls 
> should I be aware of concerning this receiver as I restore 
> it.
> Thanks in advance.
> Bob.
> VE7CPO
> Vancouver Island.

     A tip someone on the list gave me: the local oscillator 
operates _below_ the signal frequency on the top two bands. 
If you get it on the wrong side the calibration and tracking 
will be way off. Its not mentioned in either the HQ-129-X or 
HQ-120-X books but is in the HQ-140-X which is very similar 
to the earlier models but made with miniature tubes.
     The HQ-129-X is a neat receiver, much better performing 
that one might think. Surprizingly stable.
     The IF has a couple of over coupled transformers and 
should really be set up with a sweeper but you can sort of 
fake it by ear. When set up properly the passband has a 
fairly flat top about 4 khz wide and steeper skirts than 
most other similar receivers even some later ones. With some 
care in tuning it does just fine on SSB and is a very good 
CW receiver partly beacause of the excellent Hammarlund 
crystal filter.
     I need to recap mine. Although it has molded case caps 
they are probably still far from their original quality 
besides which modern film or ceramic caps are much better 
than those of sixty years ago. You can use ceramics for the 
RF and IF stages but use film caps for audio.


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