[Johnson] Are there " good" modifications ? -yes!

[Peter Markavage]

No problem Dave. I owe it all from being around you guys. 

Also, as Gary pointed out, with many high power transmitting tubes, i.e.
plate voltages greater than 1KV, the "instant on" should not be used.
Either control it with a separate switch or use some type of  time-delay
circuitry to bring the filament(s) up to operating temperature before
applying the high voltage. Of course, tubes like the 572B, used in the
SB-200/201, have no cathode, and so Heath decided to not provide any
standby switch or time-delay. 2K plus volts hit the plates as soon as you
turn the rig on.

Pete, wa2cwa

On Fri, 23 Jul 2004 10:35:50 -0700 "David Harmon" <K6XYZ at comcast.net>
writes:
> Pete....you are sooo knowledgeable.
> You have cleared up many questions I have had for many years.
> Thanks for your well worded comments....I will remember them.
> 
> Regards
> 
> Dave Harmon
> NSRCA 586
> K6XYZ[at]comcast[dot]net
> Torrance, Ca.
> 
> -----Original Message-----
> From: johnson-bounces at mailman.qth.net
> [mailto:johnson-bounces at mailman.qth.net] On Behalf Of Peter 
> Markavage
> Sent: Friday, July 23, 2004 9:54 AM
> To: Johnson at mailman.qth.net
> Subject: Re: [Johnson] Are there " good" modifications ? -yes!
> 
> Having had several B  and C lines, TR-4, TR-4C, and several TR-6's 
> over
> the last 25 years, I have never experienced any tube degradation
> (cathode
> stripping or any other anomaly) due to the "instant on" of the HV 
> power
> supply. I also presently use several of the National NCX series
> transceivers(3, 5, 200, 500) with the same type of "instant on" 
> power
> supply and suffer no tube problems. 
> 
> As to your other post concerning "electrically matched sweep tubes", 
> I
> only "match" my sweep tubes most of the time by manufacturer. I 
> will
> agree that some manufacturers, because of probably different
> manufacturing processes, developed identical tube types that were
> slightly different in their physical and electrical parameters. For 
> me
> to
> find electrically matched sweep tubes is a waste of time because it
> would
> also require that I constantly verify all the circuitry components
> surrounding the tubes to  be "electrically matched". No two tubes 
> age at
> the same rate so after several hours of operation, your 
> electrically
> matched scenario crumbles.
> 
> Pete, wa2cwa
> 
> 
> On Fri, 23 Jul 2004 09:30:45 -0400 "Sherrill E. Watkins"
> <SEWATKINS at dgs.state.va.us> writes:
> > Pete: My experience with Drake equipment does not substantate that 
> 
> > position.
> > I am not talking about audiophiles. - 73- k4own.
> > 
> > -----Original Message-----
> > From: Peter Markavage [mailto:manualman at juno.com] 
> > Sent: Friday, July 23, 2004 1:38 AM
> > To: > Subject: Re: [Johnson] Are there " good" modifications ? 
> -yes!
> > 
> > 
> > And the audiophiles also worry about too much oxygen in their 
> > speaker wires
> > and a burn-in period for their AC line cord too. In our 
> boatanchor
> > communications type gear, stripping electrons from the cathode is 
> 
> > generally
> > the least of our problems.
> > 
> > Pete, wa2cwa
> > 
> > On Thu, 22 Jul 2004 20:42:17 -0700 "David Harmon" 
> > <K6XYZ at comcast.net>
> > writes:
> > > There is a condition called 'cathode stripping' when B+ is 
> applied 
> > 
> > > before the filaments are hot. The audiophiles mostly are 
> concerned 
> > 
> > > about this. I'm not sure that this condition will cause a 
> > detectable
> > > performance
> > > degradation over a lifetime or two but it does exist.
> > > 
> > > Regards
> > > 
> > > Dave Harmon
> > > NSRCA 586
> > > K6XYZ[at]comcast[dot]net
> > > Torrance, Ca.
> > > 
> > > -----Original Message-----
> > > From: johnson-bounces at mailman.qth.net 
> > > [mailto:johnson-bounces at mailman.qth.net] On Behalf Of Gary 
> > Schafer
> > > Sent: Thursday, July 22, 2004 7:49 PM
> > > To: Sherrill E. Watkins
> > > Cc: Johnson at mailman.qth.net
> > > Subject: Re: [Johnson] Are there " good" modifications ? -yes!
> > > 
> > > There is nothing wrong with applying B+ to a cold tube. It is 
> > done
> > > all 
> > > the time in lots of equipment. Look at all the Heath equipment. 
> 
> > > Hw101, 
> > > sb101 etc. They all have solid state supplies and the HV comes 
> on 
> > 
> > > the 
> > > instant the switch is turned on. Cold filaments and all.
> > > 
> > > Hallicrafters made the HA6 and HA2, 6 and 2 meter transverters, 
> 
> > that
> > > 
> > > operated from the same power supply. All the voltages were fed 
> to
> > > both 
> > > units at the same time. The way one or the other was selected to 
> 
> > > operate
> > > 
> > > was to turn on the filament power on only the one you wanted to 
> 
> > use.
> > > The
> > > 
> > > other one sat there with cold filaments and all the high 
> voltages
> > > applied. Worked fine.
> > > 
> > > Small tubes do not have a problem with voltages applied before 
> > they
> > > are 
> > > warmed up. When you get into larger tubes with over 1000 volts 
> on 
> > 
> > > the 
> > > plate then you start worrying about that.
> > > 
> > > 73
> > > Gary  K4FMX

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