[Hammarlund] Retubing an HQ-180

Fri, 29 Mar 2002 15:13:31 -0500

I would second Glen's recommendations. No need to re-tube an entire set.
Wasteful, expensive, and bound to cause additional problems, such as the
need for re-alignment. NOS tubes go through a "break-in" period for the
first 100 hours or so. During that time, any marginal manufacturing defects
are likely to show themselves, and the "characteristics" of the tube will
change slightly. Once the tube passes this milestone, it is very likely that
it will perform properly for many years. There are, of course, some
exceptions to this rule, mainly power handling tubes, such as rectifiers, or
audio outputs. Their life is usually shorter, primarily due to the high heat
associated with the pass current of these types. I have an HQ-180 that I
acquired about 10 years ago. With the exception of the rectifier, the set
still has all the same tubes that were in it when I got it, and the set
still performs fine.
One thing that I WOULD recommend: remove the 5U4 and replace it with a 5V4.
This achieves some delay of the B+ as the filaments warm up, and will
contribute to a longer life of the whole radio.
Chuck N1LNH
-----Original Message-----
From: Mike McCoy <[email protected]>
To: [email protected] <[email protected]>
Date: Friday, March 29, 2002 9:51 AM
Subject: [Hammarlund] Retubing an HQ-180


>I just had to replace the 12AU7 BFO-meter tube in my active 180 (which I
>stole from from an older retubed 180). Because I needed to replace a tube
>(and not having a tube tester to check the rest) makes me think I might
>want/need to completely retube it in the not too distant future.
>
>Of course it's likely the original RCA tube was marginal to begin with but
>swapping that one tube with a Phillips JAN really seemed to make it even
>'hotter' than before. This brings me to my question:
>
>Assuming I stay with the NOS variety, while it might be 'any ol tube will
>do' does anyone have any advice/recommendation as to particular
>manufacturers of tubes for particular sections? For example, is there a
>particular 'brand' or variety that others have found better for certain
>applications... e.g. Phillips JAN vs 'generic Sylvanias' in the RF/IF,
>Telefunken (Mullard, etc.) in the audio, etc.?
>
>Thanks,
>Mike
>
>
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