Daily GLOWBUGS
Digest: V1 #74
via AB4EL Web Digests @ SunSITE
Purpose: building and operating vacuum tube-based QRP rigs
Subject: glowbugs V1 #74
glowbugs Sunday, July 13 1997 Volume 01 : Number 074
Date: Fri, 11 Jul 1997 14:03:49 -0600
From: mack@mails.imed.com (Ray Mack)
Subject: Re: Transformer volt/amp ratings vs the real world
Jeff and fellow glowbugs:
A VA is literally what it says Volts times Amps. You may say
that that is the formula for Watts but there is a wrinkle when the
Amps are AC power. V times A *only* gives watts when the power factor
is 1.0000. The transformer is really rated for current and not power
since we know what voltage it is inteded for and the I squared R
losses are really the worrisome factor along with core losses again
due to current and *not* power.
Said another way VA is the same regardless of power factor
whereas power changes acording to power factor.
I suspect that Bobbi has better information or a better way of
explaining it.
Ray Mack
WD5IFS
mack@mails.imed.com
______________________________ Reply Separator _________________________________
<snip>
But I got the new All Electronics catalog yesterday, and it includes a nice
little isolation transformer about the size of those 125V, 50ma
transformers I used to use in the Sixties for one and two tube projects.
The trouble is, the catalog gives its rating as 50VA, or 425ma!
Now, there's no way (in my experience) that a 2" square U-strap transformer
will source 400+ mils. So what, if anything, does a volt/amp rating mean,
and how do we translate such ratings to realistic expectations of current
sourcing ability? I've noticed before that VA ratings seem unusually
generous. I'm wondering if anybody here can clarify this point.
<snip>
Date: Fri, 11 Jul 1997 15:07:47 -0500
From: Conard Murray <ws4s@InfoAve.Net>
Subject: Transformer 'idling' current query
Hello all,
I have a question regarding the no-load primary current in power
transformers.
I posted a query a while back regarding escaping goo from a transformer
I was attempting to use in a BA project. The transformer is rated at
1250-0-1250 volts at 500 mA. I was feeding it with a Variac and taking
the output through a half-wave rectifier to try and reform some old
electrolytic caps. The maximum primary voltage was only 20 volts or so.
When I went to move it off the bench I noticed a small quantity of black
goo seeping out of the end bells.
A few days ago I tested the transformer with no load on the secondary
and found 3.5 amps flowing in the primary with 120 VAC applied. I was
using a DVM to measure the current. I tried another transformer rated at
3100-0-3100 at 1200VA (there goes the VA thing again!) and it was
pulling about 1.5 amps with the same setup. The second transformer has a
much larger core than the first.
I think I have a shorted turn in the first transformer. It never got
warm under reduced voltage usage, but it would take a bit of heat to get
that hunk of iron hot. I also have no idea what the phase angle of the
current I measured was, so most of the power I was seeing might have
been reactive.
Anyone have any ideas here?
Thanks,
Conard
Date: Sat, 12 Jul 1997 02:09:23 +0000
From: Sandy W5TVW <ebjr@worldnet.att.net>
Subject: BA/GB "net
Hello anchorites/glowbuggers,
Made fairly successful test tonight on 7117 starting about 0100
thru about 0200 GMT. Had some Mexican SSB intruders around 0200 briefly.
Present were: W5FRS- Dennis, K2LMQ- Paul, W7ZFB- John and W5TVW-Sandy.
Will be also checking the 7050 and 7060 QRG's for a while to pickup
stragglers. We are hunting for a better frequency, so bear with us.
Something to have a minimum of SSB QRM and digital QRM on.
It's hard enough to cope with the summertime static, let alone
the other stuff!
See you guys there!
73,
E. V. Sandy Blaize, W5TVW
"Boat Anchors collected, restored, repaired, traded and used!"
417 Ridgewood Drive,
Metairie, LA., 70001
ebjr@worldnet.att.net
**Looking for: 860 tubes, WL-460 tubes**
**RK-34(VT-224) tubes, Butternut HF2V antenna***
Date: Fri, 11 Jul 1997 20:27:46 -0800
From: "Kenneth G. Gordon" <keng@uidaho.edu>
Subject: Re: BA/GB "net
>
> Made fairly successful test tonight on 7117 starting about 0100
> thru about 0200 GMT. Had some Mexican SSB intruders around 0200 briefly.
> Present were: W5FRS- Dennis, K2LMQ- Paul, W7ZFB- John and W5TVW-Sandy.
Seems to me that the higher up you go the MORE likely you will be to
get SSB/Digital QRM. Why not go a little lower...like 7026...or
below.
> Something to have a minimum of SSB QRM and digital QRM on.
> It's hard enough to cope with the summertime static, let alone
> the other stuff!
Down, not up.
Ken W7EKB
Date: Fri, 11 Jul 1997 21:36:39 -0700
From: Richard Wilkerson <richqrp@cts.com>
Subject: Re: BA/GB "net
Kenneth G. Gordon wrote:
>
> >
> > Made fairly successful test tonight on 7117 starting about 0100
> > thru about 0200 GMT. Had some Mexican SSB intruders around 0200 briefly.
> > Present were: W5FRS- Dennis, K2LMQ- Paul, W7ZFB- John and W5TVW-Sandy.
>
> Seems to me that the higher up you go the MORE likely you will be to
> get SSB/Digital QRM. Why not go a little lower...like 7026...or
> below.
>
> > Something to have a minimum of SSB QRM and digital QRM on.
> > It's hard enough to cope with the summertime static, let alone
> > the other stuff!
>
> Down, not up.
>
> Ken W7EKB
*******
Not too low Ken, dummies like me cant go below 25????? I know I know
upgrade, upgrade.............
- --
72's........ Rich
Rich Wilkerson, WD6FDD, Santee, Ca.
NorCal, ARCI, ScQRPions, E.C.R.A.
Boatanchors
Date: Sat, 12 Jul 1997 03:42:02 -0700 (PDT)
From: Ken Gordon <keng@uidaho.edu>
Subject: Re: BA/GB "net
> > Down, not up.
> >
> > Ken W7EKB
> *******
> Not too low Ken, dummies like me cant go below 25????? I know I know
> upgrade, upgrade.............
Ah! Yes. It was not my intention to exclude anyone. Perhaps I might
remind Sandy and the others that if we get up into the Novice band we will
ALL be required to run Novice power levels in order to be legal. No more
Big Bertha's or pairs of 813's.
Ken W7EKB
Date: Sat, 12 Jul 1997 07:45:16 -0500 (EST)
From: "Roberta J. Barmore" <rbarmore@indy.net>
Subject: Re: BA/GB "net
Hi!
Um, there's one other problem with movin' the BA-freq around: some of
us (well, me) are rockbound! Might be able to squeak the 7120kc job down
to 7117; otherwise I'll be out 'til I can order some new crystals.
...OTOH and especially now that Pheonix is in biz, no less a light than
Fred Sutter, W8QBW remarked that crystals had become cheap enough the one
could accumulate quite a few without huge expense; that was sixty years
ago and he's still right. So it's not too onerous a thing.
Who knows, might even find one at the Indy Hamfest today! To which I
shall be off now, with high hopes and more cash than I otta. :)
73,
--Bobbi
Date: Sat, 12 Jul 1997 09:44:13 -0500 (CDT)
From: Bob Roehrig <broehrig@admin.aurora.edu>
Subject: FRRL Hamfest
Anyone going to the Fox River Radio League hamfest in Sugar Grove, IL
tomorrow? I'll be there in the AM and will monitor 147.54 simplex as
I am wandering around.
E-mail broehrig@admin.aurora.edu 73 de Bob, K9EUI
CIS: Data / Telecom Aurora University, Aurora, IL
630-844-4898 Fax 630-844-5530
Date: Sat, 12 Jul 1997 08:06:19 -0700 (PDT)
From: Ken Gordon <keng@uidaho.edu>
Subject: Re: BA/GB "net
>
> Hi!
>
> Um, there's one other problem with movin' the BA-freq around: some of
> us (well, me)
AND ME!
>are rockbound! Might be able to squeak the 7120kc job down
> to 7117;
I have a 7160...also 7020 and 7015
> otherwise I'll be out 'til I can order some new crystals.
Likewise: this "cross-band" stuff doesn't work: no one listens off their
own frequency...except myself.
> ...OTOH and especially now that Pheonix is in biz, no less a light than
> Fred Sutter, W8QBW remarked that crystals had become cheap enough the one
> could accumulate quite a few without huge expense;
Yes, but still an expense which, at least in our household, is hard to
justify.
> that was sixty years
> ago and he's still right. So it's not too onerous a thing.
> Who knows, might even find one at the Indy Hamfest today! To which I
> shall be off now, with high hopes and more cash than I otta. :)
Good luck. Tell us what you find.
Ken W7EKB
Date: Sat, 12 Jul 1997 08:33:40 -0700
From: Richard Wilkerson <richqrp@cts.com>
Subject: Re: BA/GB "net
Roberta J. Barmore wrote:
>
> Hi!
>
> Um, there's one other problem with movin' the BA-freq around: some of
> us (well, me) are rockbound! Might be able to squeak the 7120kc job down
> to 7117; otherwise I'll be out 'til I can order some new crystals.
> ...OTOH and especially now that Pheonix is in biz, no less a light than
> Fred Sutter, W8QBW remarked that crystals had become cheap enough the one
> could accumulate quite a few without huge expense; that was sixty years
> ago and he's still right. So it's not too onerous a thing.
> Who knows, might even find one at the Indy Hamfest today! To which I
> shall be off now, with high hopes and more cash than I otta. :)
>
> 73,
> --Bobbi
********
Yes Bobbi, I also run crystals here, I was in that last group buy of
the "general" set. If someone is not right on the freq. I have to go
to my very drifty VFO and I know that must drive everyone nuts!!!!!!
HI HI.........
- --
72's........ Rich
Rich Wilkerson, WD6FDD, Santee, Ca.
NorCal, ARCI, ScQRPions, E.C.R.A.
Boatanchors
Date: Sun, 13 Jul 1997 12:52:22 -0500 (EST)
From: "Roberta J. Barmore" <rbarmore@indy.net>
Subject: Indy Hamfest
Hi!
Well, I went to the Indy Hamfest yesterday; didn't meet any list
members as far as I recall, but I did pick up a nice sunburn and still
coping with a *massive* headache from too long in the bright sun. :)
Ahh, but worth it! One regret, I looked at a couple of nice Globe
Scouts ($25 @) and intended to buy one...then got distracted and didn't
get back to 'em in time: seller had packed up and left!
What did I buy? Wellll...a Shure 3-A carbon mic and stand, $70; this
is a spring-suspended job. The cast-metal stand has been broken and
superglued (arrgh) but will get epoxy unless someone here can tell me how
to braze such material. It is reputed to be in working shape!
A Les Logan Speed-X bug with an unusual yoke--it's got a nice big
T-bar, and a round hole through which the arm passes, as if Les had been
getting telepathic influence from Mac & T.A. Co. Plating on the yoke is
flaking *badly* and there are a few cracks in it at the far ends of the
T-bar. (Attn serious key collectors: is it kosher to have this replated?
Is it *safe* to do so with the observed cracks?). Gave $75, which seemed
about right.
Same fellow who had the Logan had a lot of nice Vibroplexes, including
a japanned-base with most of the pinstriping intact for $225 (I passed);
also some nice Signal and Mac & T.A. Co. streamkeys not too horribly
overpriced. Elsewhere, I saw another japanned-base Vibro, with landline
points and *most* of the pintriping in FB shape; but the nitwit had
slapped a huge hunk of tape over one corner and wanted $325 firm!
Mentioned to him that damage to the striping was likely and would reduce
the value, and was told, "I don't care, I just sell 'em." Idiot!
Picked up a '40 ARRL HB, "Radio" mags from April & Aug '34 (very nice)
and June '43--by that date, the entire West Coast gang was g-o-n-e and it
was, well, not really too much of a magazine, alas. The Bernie Ontiveros
draftmanship is conspiious
End of glowbugs V1 #74
**********************
Created by Steve Modena, AB4EL
Comments and suggestions to modena@SunSITE.unc.edu