[VHFcontesting] [NEWSVHF] 222 Activity Night
David Olean
k1whs at metrocast.net
Thu Jun 17 16:37:27 EDT 2021
Hi Pete,
Well, I wasn't rolling on the floor laughing when it happened. I went
looking for my hard hat and ducked as the shrapnel flew around behind
the rack! The good news is that the amp is OK. I dragged it home to
look it over. There are some protective diodes in the metering circuit
and those usually short out when there is a tube arc. I checked those
and both seemed fine. The 12 volt 50 watt zener bias diode also looked
OK. I had to rebuild the fuse holder as part of it was missing after
the bomb went off. I found a big fuse clip thingey in some old surplus
stuff, and stole the two fuse clips to fix the amplifier. I got that
done and then replaced the fuse with a new 1.5 amp HV fuse. I tried it
out and the amp came up just fine down in the shop.I ran some 222 energy
into the amp from my signal generator. I had a wideband amp that will
make about 4 watts so I stuck that into the 8877 input connector and saw
100 watts coming out. That is over 13 dB gain so it all looks OK.
So what happened? It could have been that the fuse just decided that it
was time to give out. It would make a pretty good noise just letting
go. It could have been a tube arc, but having good protection diodes
afterward, makes me think that maybe there was not an arc at all. With
all the news stories about politics lately, it also could have been
caused by Donald Trump. I am going to stick with that explanation, or
maybe it was cosmic rays from outer space. Everyone knows that cosmic
rays are really bad too.
All this leaves me wondering about my crazy idea to use electrolytic
capacitors as HV caps in series for HV filtering I think I went
overboard a bit. The end result is a huge capacitor bank value of 166
MFD. That is a good amount of stored up energy at 3500 volts. If
anything in the HV line wants to consume current, 166 MFD will surely
oblige that request. I think I might remove the electrolytic bank and
substitute a modern non PCB 6 MFD 10 KV cap instead. That way, if I get
another arc, it will sound like a 30 cal handgun instead of turret B on
the USS. Missouri!
Maybe I should use #32 wire as Jay recommended. I went with smaller
stuff, like #47. It will pull over an amp without burning out, so I
figured it was OK. I tried running some current through some #32 wire
and it will do 5 amps. If I push the current higher, it breaks open at 7
or 8 amps, which seems awfully high to me. That is 28 kilowatts.
73
Dave K1WHS
On 6/16/2021 11:10 PM, Peter Motyl wrote:
>
> Yah, but reading about the explosion had me rolling on the floor with
> laughter. Oh, I know from experience it isn’t funny when it happens
> but reading about it is really funny.
>
> *From: *jrusgrove at comcast.net <mailto:jrusgrove at comcast.net>
> *Sent: *Wednesday, June 16, 2021 6:22 AM
> *To: *David Olean <mailto:k1whs at metrocast.net>; Fred Stefanik
> <mailto:n1dpmfred at gmail.com>
> *Cc: *222 >> 222Activity at groups.io <mailto:222Activity at groups.io>; VHF
> Contesting <mailto:vhfcontesting at contesting.com>; NEWS Reflector
> <mailto:newsvhf at mailman.qth.net>
> *Subject: *Re: [NEWSVHF] 222 Activity Night
>
> Dave
>
> If you don't have it the circuit already, I'd suggest a 'glitch'
> resistor in series with the HV output to limit current to a high, but
> manageable, level. Also, for a high voltage fuse, try a small length
> of #30 - 32 wire (approx) between two ceramic standoffs. Since these
> two items have been in place I've experienced no fireworks or power
> supply damage when an amplifier 'incident' occurs ... everything shuts
> down quietly. Previous to this I've experienced a number of
> flash/bangs as you, and others, have.
>
> Jay W1VD
>
> ----- Original Message -----
>
> From: David Olean <k1whs at metrocast.net>
>
> To: Fred Stefanik <n1dpmfred at gmail.com>
>
> Cc: 222 >> 222Activity at groups.io <222Activity at groups.io>, VHF
> Contesting <vhfcontesting at contesting.com>, NEWS Reflector
> <newsvhf at mailman.qth.net>
>
> Sent: 6/15/2021 11:43:15 PM
>
> Subject: Re: [NEWSVHF] 222 Activity Night
>
> ________________________________________________________________________________
>
> Well I was very happy that Fred N1DPM showed up for 222 activity night.
>
> We had a nice rag chew and signals were 59+ each way. Fred's signal was
>
> outstanding. I listened to Fred run with KO4YC near Richmond, VA.
>
> K04YC was peaking up really fine, hitting a good 559 on the S-meter.
>
> That is pretty impressive for over 500 miles away. I tail ended KO4YC
>
> and called Fred. I had worked Cornell earlier with my driver amp at 80
>
> watts. It was a squeaker, but while I was ragchewing with N1DPM, KO4YC
>
> heard me OK on ssb with my 80 watts, so there were definitely some good
>
> tropo peaks going on. You should not be able to work 525 miles with 80
>
> watts on 222 normally.
>
> A try with VE3DS was not successful with my 80 watts. Still it was a
>
> great evening on 222 with 13 stations worked including
>
> KA2LIM Ken in FN12
>
> W9KXI Al also in FN12 Ken and Al seem to be FN12!!
>
> WW1M Bruce in FN43 (just down the road a few miles)
>
> WA1LWC in FN42 5 watt power house!
>
> VE2XX Stu near Montreal in FN25. I could hear him working KA2LIM. 59
>
> when we aimed at each other!
>
> N1SV Les in FN42 One of the 222 night regulars
>
> WZ1V Good Buddy Ron. Always shows up for 222 night and stirs up the
>
> pot with lots of contacts.
>
> N3RG Ray way down at the bottom of FM29
>
> K3WHC Steve in FN10pa.
>
> K1PXE Pete in FN31. The voice of Milford! and a staunch supporter of
>
> activity night.
>
> WA2VNV in FN30 on Long Island with a booming signal up here in Maine.
>
> K2AEP Pete in FN33 Vermont. One of the few people who keeps a briefcase
>
> full of alphabetically organized jokes.
>
> KO4YC Cornell in FM17 near Richmond, who must have a fantastic takeoff
>
> angle. Just a phenomenal signal up here every week.
>
> I had some excitement here. Not too long after I got on the air, There
>
> was a very large explosion and a flash behind the rack as the 222 MHz
>
> 8877 amp decided to arc over. I hate it when that happens. The high
>
> voltage fuse is about 4 1/2" long and is a phenolic tube with brass end
>
> bells. When it went off. The two end bells were blown out of the tube
>
> ends and one of the brass end bells shattered into little pieces. It
>
> even blew up the beryllium copper fuse holders! This could be serious.
>
> At a minimum, I probably have shorted diodes in the metering circuit. At
>
> worst, the tube might be hosed. I dragged it back to the house and will
>
> look it over in the morning.
>
> I recall this happened another time many years ago with this same
>
> amplifier on Pack Monadnock Mountain in New Hampshire during a June
>
> Contest. The 220 rig was set up in a cargo van and I had built up an
>
> eight yagi array of NBS 4.2 wavelngth design for EME. The group was W1FC
>
> and there was an aurora on both Saturday and Sunday evening. We were
>
> cleaning up on 220 MHz and our section total was way ahead of the 144
>
> station. I remember working Iowa and Minnesota that weekend along with
>
> EME to California. Word got around that we were doing so well, and a
>
> crowd formed all poking their heads in the van door to see what we were
>
> doing. At that exact time, the 8877 amp decided to arc over and that
>
> same HV fuse exploded. It sounded like someone shot off a M1911 45cal
>
> pistol inside the van and to add some spice to the effort, the two end
>
> bells went ricocheting off the walls of the van. The crowd instantly
>
> thinned out and we replaced the fuse and got back to working DX.
>
> Thanks to all who came out to play, including Marshall, K5QE from Texas.
>
> He ran some MS schedules. Thanks Marshall!
>
> 73
>
> Dave K1WHS
>
> On 6/15/2021 9:59 PM, Fred Stefanik wrote:
>
> > I was able to get on 222 here tonight for about 30 minutes. I worked
>
> > VE3DS at 369 miles, KO4YC at 385 miles, and K1WHS at 125 miles.
>
> > Hopefully I can get on more often on Tuesday nights.
>
> > Thanks Dave for drumming up the activity!
>
> > 73
>
> > Fred
>
> > N1DPM
>
> > FN32qb
>
> >
>
> > On Tue, Jun 15, 2021, 5:18 PM David Olean <k1whs at metrocast.net
>
> > <mailto:k1whs at metrocast.net>> wrote:
>
> >
>
> > Just two days after the big June VHF Contest. I know everybody is
>
> > probably sick to death of working 50 MHz DX. You would most likely
>
> > rather do anything but more ham radio, but it is 222 Night! I
> will be
>
> > on starting around 7 or 7:30 PM local time or 2300 UT and will be
>
> > making
>
> > noise on 222.100 thereabouts. When we quit contesting Sunday
>
> > night, I
>
> > am sure that the diesel generator was running on fumes. I will
>
> > drag up a
>
> > 6 gallon can of diesel fuel to make sure I don't run out.
>
> >
>
> > I hope to see you on 222 MHz
>
> >
>
> > Dave K1WHS
>
> >
>
> > ______________________________________________________________
>
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>
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>
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