[Hammarlund] Tube Brands & replacement

[Tim Kass]

I would have to agree completely with Glen on this as well...I never replace 
tubes unless it is found that the tube is short or gassy...then I replace it 
usually with at least a USA equivalent. Some of the foreign tubes made were 
of poor quality, that has changed over time but better to keep with an US 
brand as they tend to try to keep their values the same.  In transmitters 
however, particularly finals, there appears to be more variation, so keep 
with the same brand if possible.   One trick I've found, this may not be 
recommended, but if the tube tests as weak, I will dial up the filament 
voltage on the tester to the next higher value for a moment.  This has 
sometimes appeared to "rejuvinate" the weak tube sometimes.  Generally, 
well, atleast with the Hammarlunds and Hallys I have, the RF coils or 
antenna coils need to be "peaked" just a bit to bring it up to 
specifications.  So do an alignment first before deciding on tube 
replacements..unless of course the tube is gassy or shorting..

73, Tim
K8WBL




>From: Glen Zook <gzook at yahoo.com>
>To: Eugene Balinski <eugeneb at nni.com>,Hammarlund List 
><hammarlund at mailman.qth.net>
>Subject: Re: [Hammarlund] Tube Brands & replacement Date: Fri, 31 Mar 2006 
>08:50:11 -0800 (PST)
>
>I never replace all of the tubes in a unit just to
>replace the tubes.  Tubes last for decades and unless
>the unit is not performing up to specifications
>replacing all of the tubes can cause problems.  Even
>replacing all of the tubes in a particular circuit may
>cause problems especially if the tubes "age" at
>different rates.
>
>If you are having problems that can be traced to one,
>or more, tubes, then most certainly replace them.
>But, just to replace a tube for the sake of replacing
>the tube is not recommended.
>
>Remember that the best tube checker around is the unit
>itself.
>
>As for any particular brand being better than another,
>remember that many of the tube manufacturers marked
>the tubes with all sorts of brands.  Thus, a tube
>marked "GE" may have come down the same assembly line
>as one marked "RCA" and so forth.
>
>JAN tubes are usually, but not always, of top quality.
>  But, there have been some really bad tubes produced
>for the military by companies that have gotten paid
>for their output then the company has just faded into
>the woodwork.
>
>Glen, K9STH
>
>
>--- Eugene Balinski <eugeneb at nni.com> wrote:
>
>Is there a preferred tube BRAND ? I have always
>favored RCA and Sylvania tubes.  Are there any in
>particular (besides some of the unknown brands) to
>avoid?    Any value in getting the ex-military JAN
>tubes ?
>
>
>
>
>
>
>
>
>
>Glen, K9STH
>
>Web sites
>
>http://home.comcast.net/~k9sth
>http://home.comcast.net/~zcomco
>
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