patents@dx0man.prestel.co.uk wrote:
> Thanks Steve & Jerry ! Two points:-
>
> (i) if the J-310s feel warm (= hot ?) after some period of
> use, then perhaps its time to fit clip-on heat sinks ??
> The one(s) with lowest internal R will presumably run hotter and their
> parameters will tend to drift faster than the cooler ones. Not very
> fast perhaps, but with prolonged use then who knows ?? This could be
> the kind of fault that gradually sneaks up on you.
>
> I think I now have a clue as to why my OMNI-V RF gain seems to drop
> slowly over several hours, if I leave it running. The effect is that
> on 10/12/15/17 and even 20 when the band is near dead. I need to
> steadily increase the RF gain setting, to over-ride the IF/audio
> noise. Note that I'm talking hours here and its much less noticable if
> the bands are lively.
>
> (ii) those switching diodes .... I checked my notes and I see that I
> researched their replacement to avoid ordering them from TT and
> getting hit by airmail and even Customs charges. But in the end I
> found them listed by a small UK parts house who regularly attend
> hamfests. They were happy to get me a bag full of the original BA
> 482s and you are right; they are vhf switching diodes and its unclear
> if the architecture is PIN. Now to ask them if they will do a similar
> low cost deal for a bag of J-310s.
>
> 73 - John G3JAG
>
> On 23-Jan-99 Steve Baron wrote:
> > Understand.
> >
> > This radio was used when I got it Happened to check the 310
> > voltages one
> > day and found that most were around 1.5 (1.7 ?) volts. Some were
> > as low as
> > 0.5 volts.
> >
> > Replaced some (from TT) and all came up to the higher value. That
> > was a few
> > (5 ?) years ago. My impression at the time was that it cleaned up
> > 40 and
> > 80; note that very quantitative statement.
> >
> > Just spot checked them a few weeks ago while doing something else,
> > and saw
> > that a few (2 ?) had dropped to about 0.9...so I asked the
> > question. Sort
> > of a purely academic question.
> >
> > My impression is they work (have to) fairly hard (feel them) and
> > maybe they
> > really do change - at least some of them.
> >
> > Not paranoid about it...just curious.
> >
> > My recollection is that TT recommends not replacing their diodes.
> > Looked
> > into it once and found out that the diodes they use are kind of
> > funny --- if
> > I remember correctly, they are described as pin diodes but really
> > may not be
> > exactly ...think their recommended use was rf switching at VHF freq
> > ?
> >
> > We have had several excellent quantitative articles by several
> > authors who
> > have highlighted the improvement which can be obtained by changing
> > some of
> > the diodes in some rigs - rigs that we know have problems and ones
> > which we
> > did not buy - perhaps exactly because of those problems.
> >
> > I would not switch my diodes without some proof - quantitative - of
> > improvement.
> >
> > My impression is that one must be careful with diode selection
> > since
> > impedance in the on state, current requirements, etc are all
> > important.
> > All pin diodes are not created equal and unless you select the
> > right one and
> > 'install' it properly you may be wasting your time...gee, wonder if
> > you
> > could get a 'quieter' rig because your diodes weren't switched
> > fully on!
> >
> > Hope that helps
> > -----Original Message-----
> > From: patents@dx0man.prestel.co.uk <patents@dx0man.prestel.co.uk>
> > To: Steve Baron <stevebaron@starlinx.com>
> > Cc: TenTec <TenTec@contesting.com>
To: <tentec@contesting.com>
> > Date: Saturday, January 23, 1999 2:25 AM
> > Subject: RE: [TenTec] OMNI V J310's
> >
> >
> >>
> >>I'm intrigued by your query about the OMNI-V J310's. I have an
> >>OMNI-V
> >>and its now quite ancient. Are there any symptoms associated with
> >>J310 ageing ?? I feel, but cannot verify, that I've recently been
> >>getting more intermod than I used to get when the rig was newer,
> >>especially on 40m. Could be that the European QRM is a lot louder
> >>now
> >>I use ladder line instead of 100ft of coax, but it has occurred to
> >>me that I might also have a front end problem developing. The
> >>front
> >>end sensitivity on the HF (20 and up) bands appears to be low,
> >>although I can hear signals way down to the antenna noise if I
> >>crank
> >>up the RF gain. I cannot crank up the audio gain without getting
> >>noise of the wrong sort - not from the antenna. (My RF gain is
> >>usually
> >>well up, at 3-4 PM; audio stays down at 9-10 PM).
> >>
> >>The J310 is easily obtainable here, but I'm not sure how to set
> >>about
> >>matching a set of four. I think any replacement must use a well
> >>matched set, or it will defeat the object of sharing the work load.
> >>
> >>Incidentally, I replaced all the front end switching diodes with
> >>locally obtained pin diodes (not necessarily the best ones for the
> >>job - see recent comment on Paragon diode swap). This was before I
> >>discovered the obvious - I had a stuck reed relay !! There was no
> >>noticable performance improvement, even when I fixed the relay
> >>(with the help of the TT service dept).
> >>
> >>But I wonder if I should really be considering a complete
> >>re-alignment
> >>(is there any info on that available ?) after so much heavy use.
> >>
> >>73 John G3JAG
> >>
> >>
> >>On 20-Jan-99 Steve Baron wrote:
> >>>
> >>> A few years ago I noticed that the voltage on a few of the J10's
> >>> was
> >>> significantly lower (0.5 to 1 V) than the others which were up
> >>> around 1.5
> >>> (1.7 ?) or so. Replaced some and all were 'balanced'.
> >>>
> >>> Recently had the covers off and checked them again and saw that a
> >>> few had
> >>> dropped again.
> >>>
> >>> Would appreciate any input on the effect of reduced voltage - and
> >>> perhaps a
> >>> number for the lowest that should be tolerated.
> >>>
> >>> Thanks.
> >>>
> >>>
> >>>
> >>> --
> >>> FAQ on WWW: http://www.contesting.com/tentecfaq.htm
> >>> Submissions: tentec@contesting.com
> >>> Administrative requests: tentec-REQUEST@contesting.com
> >>> Problems: owner-tentec@contesting.com
> >>> Search:
> >>> http://www.contesting.com/km9p/search.htm
> >>
> >>----------------------------------
> >>E-Mail: patents@dx0man.prestel.co.uk
To: <tentec@contesting.com>
> >>Date: 22-Jan-99
> >>Time: 14:03:35
> >>John Crux
> >>Consultant in product forgery - Asia and
> >>Africa
> >>
> >>----------------------------------
> >>
> >>--
> >>FAQ on WWW: http://www.contesting.com/tentecfaq.htm
> >>Submissions: tentec@contesting.com
> >>Administrative requests: tentec-REQUEST@contesting.com
> >>Problems: owner-tentec@contesting.com
> >>Search: http://www.contesting.com/km9p/search.htm
> >>
>
> ----------------------------------
> E-Mail: patents@dx0man.prestel.co.uk
To: <tentec@contesting.com>
> Date: 23-Jan-99
> Time: 08:41:30
> John Crux
> Consultant in product forgery - Asia and
> Africa
>
> ----------------------------------
>
> --
> FAQ on WWW: http://www.contesting.com/tentecfaq.htm
> Submissions: tentec@contesting.com
> Administrative requests: tentec-REQUEST@contesting.com
> Problems: owner-tentec@contesting.com
> Search: http://www.contesting.com/km9p/search.htm
Ideally you want to set the J310 to between 10 and 15 milliamps
quiesent, total current drain. Yes they do run a little hot/warm to the
touch. Look up the specs you'll be surprised how hot they can run.
Bill Cook N4WC
--
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