Daily GLOWBUGS
Digest: V1 #11
via AB4EL Web Digests @ SunSITE
Purpose: building and operating vacuum tube-based QRP rigs
Subject: glowbugs V1 #11
glowbugs Saturday, April 19 1997 Volume 01 : Number 011
Date: Fri, 18 Apr 1997 14:24:00 -0600
From: Alex Mendelsohn <alexm@pennwell.com>
Subject: FW: 8874's
Glenn:
Depending on what he pays for the amp, it might be worth buying it for
the components, power suplply, enclosure, etc! Then again, at the PAWA
hamfair here in Portland, Maine last week, there was a beautiful commercial
RF deck for sale in an unbelievably environmentally hardended case, for a
pair of 4-400s or 3-500Zs, or what have you. The asking price there was $70,
sans power supply parts.
Vy 73, Alex, AI2Q in Kennebunk, Maine .-.-.
----------
From: Glenn Finerman
To: ALEXM; Multiple recipients of list
Subject: 8874's
Date: Friday, April 18, 1997 8:48AM
A good friend of mine is looking at a used Alpha 76 which uses 8874's.
He had a few questions which he asked me to post to the group of
tube experts (woops! I used the "E" word!!!). I told him this group is as
close as you're gonna get!
After he checked the AES catalog (Amateur Electronic Supply) and saw
that a replacement pair of these tubes will run almost $1000, he has
some reservations about buying the amp. I noticed those prices are
for Eimac tubes. Are 8874's available from Svetlana for less $$ ???
Are they available from ANYBODY for less than Eimac's??
I know you folks in the broadcast industry are used to such high cost
tubes, but $1000 for 2 tubes? WHEW!!. I thought a read a recent post
about an article in QST outlining a mod to amps that use these tubes
to use 3CX400's ?? Not sure about that.........
What should he do? I know Alpha makes a great amp and I don't want
to advise him to buy an Ameritron. He will be mainly using the amp to
amplify a low power plate modulated AM transmitter and some SSB.
HELP??
73.........Glenn N2BJG gfiner@nms.com
Date: Fri, 18 Apr 1997 14:24:00 -0600
From: Alex Mendelsohn <alexm@pennwell.com>
Subject: 30 Amps needed
Hello all:
Is there anyoine out there that has a 30 A at 5 V filament
transformer they'd like to part with? I just finished building a pair of
4-400As in a dedicated 160 meter amplifier, and the transformer I've got in
there now is running warm; it's a tad overloaded.
Any help would be appreciated.
Many thanks es vy 73, Alex, AI2Q in Kennebunk, Maine .-.-.
Date: Fri, 18 Apr 1997 16:02:05 -0400
From: "Ornitz, Barry" <ornitz@eastman.com>
Subject: RE: XFMR CORE SATURATION
Everybody's answering their own questions lately. :-)
Transformers are designed to have a coefficient of coupling of close to
unity for audio and power transformers. Air wound coils at RF can be
used as autotransformers, but are generally used for just their
inductance. Shorting a few turns lowers the inductance of the remaining
coil but since the coefficient of coupling of air wound coils is much
less than unity, the effect is not as great as it would be in a power
transformer. [Most folks are not used to thinking that a tapped coil
can be viewed as two independent coils with a mutual inductance.]
When we think of a "slug-tuned" coil today, we generally think of a
ferrite rod being moved in and out of the coil. The ferrite has a
permeability much greater than air so sliding it into the coil increases
the inductance. However, solid or silver-plated brass slugs were often
used in the past. Inserted into a coil, they acted as a shorted turn
and they reduced the inductance of the coil. The percentage decrease in
inductance was usually far less than the percentage increase in
inductance with ferrite slugs, thus leading to a decline in their
popularity.
>From: bill@skeeter.frco.com [SMTP:bill@skeeter.frco.com]
>
>Now that's interesting. I know you can't short turns on an audio xfmr ...
>
>But I've seen some RF amps where there appears to be a tap that shorts
>out part of the coil to change bands. Can you do that at RF? Maybe
>because it's air core?
>
Date: Fri, 18 Apr 1997 17:23:00 -0600
From: Alex Mendelsohn <alexm@pennwell.com>
Subject: FW: 30 Amps needed
Thanks Spencer. Appreciate your response. Well, like so many of the gang, we
have to use what we have! I thought about using a setup like what you
describe, but didn't have the right transformer for that either! :-)
Vy 73, Alex, AI2Q in Kennebunk, Maine
PS - Tks fer the nice comments too. The amp turned out well. It uses a pair
of 8188s, which are pulse rated 4-400As. Also put a Jennings vacuum relay in
the changeover circuit. No proble with arc-ing there. HI HI.
----------
From: Spencer Petri
To: Alex Mendelsohn
Subject: Re: 30 Amps needed
Date: Friday, April 18, 1997 4:15PM
Alex,
Although I don't have a transformer, I do have a suggestion. Use a 6.3 volt
transformer with a power resistor in the primary to drop the secondary
voltage to 5VAC. In this one fell swoop you get a more common transformer
and inrush protection at the same time.
In my 6 mtr 4-1000A amp I use a 12 VAC output transformer, 240VAC secondary,
with a resistor in each side of the primary and a 120VAC variac on one side
wired in series with the transformer primary. This gives adjustment and
current protection.
Sounds like a nice amp.
Just a thought.
At 02:24 PM 4/18/97 -0600, you wrote:
>
>Hello all:
>
> Is there anyoine out there that has a 30 A at 5 V filament
>transformer they'd like to part with? I just finished building a pair of
>4-400As in a dedicated 160 meter amplifier, and the transformer I've got in
>there now is running warm; it's a tad overloaded.
>
>Any help would be appreciated.
>
>Many thanks es vy 73, Alex, AI2Q in Kennebunk, Maine .-.-.
>
73 de Pete WA5JCI
*******************************************************************
EM-21--6 Mtr -- WAS #490, WAC CW, DXCC/91 Countries, VUCC/618 Grids
*******************************************************************
2 Mtr -- 36 States -- VUCC/183 Grids
*************************************
Date: Fri, 18 Apr 1997 17:23:00 -0600
From: Alex Mendelsohn <alexm@pennwell.com>
Subject: FW: HQ-120
Hi Eric and nice to meetcha!
I use a 6L6 colpitts oscillator on 80 and 40. It usesa Type 80 rectifier for
some semblence of authenticity and a VR-150 on the screen. No chirp, but I
can "pull" the freq. with my hand on the plug-in coil. That's great fun when
signing off.
I also built a 42-47 two toober regen, which works best on 80 meters.
C'mon over sometime and take a looksee. I've worked the west coast and the
caribbean many times with the little 8 watter!
BTW: the schematics for my rigs are available as OrCAD files, and are posted
on one of the glowbug web sites; I forget which one.
Vy 73, Alex, AI2Q in Kennebunk, Maine .-.-.
----------
From: 'EWOODMAN@SMTP <EWoodman@aol.com>'
To: Alex Mendelsohn
Subject: HQ-120
Date: Friday, April 18, 1997 4:12PM
Hi Alex,
Just noticed your comment on the Glowbug List:
>I have a 1938 Hammarlund HQ-120 here that I use quite a bit, and use it
>competitively in the Antique Wireless Association's annual Old Timer Radio
>tests. It's a great receiver.
That's what I have for my "tube station" receiver. It's definitely a good
rig. Mine is in really good electrical shape. Cosmetically it's so-so. Had
to
put in a new bandspread dial and the front panel needs some help. The paint
was really worn so someone decided to try to color it with a black magic
marker. Can't imagine doing that to a nice old radio. I can put up with a
worn panel but this is UGLY. I'd like to repaint it but don't see any way to
do it and keep the lettering. Too bad it isn't engraved. At least then maybe
the letters could be filled in with paint. Oh well, guess I'll have to put
up
with the ugliness.
By the way, what do you use for old transmitters? Just curious. I've got an
old homebrew, vfo-controlled 80M rig, a homebrew replica of a 1930's Hartley
for 160 and an old Knight T-150 for AM. I'm over in New Hampshire. Maybe
we'll work each other someday.
73 Eric KA1YRV
Date: Fri, 18 Apr 1997 17:23:00 -0600
From: Alex Mendelsohn <alexm@pennwell.com>
Subject: FW: 30 Amps needed
Thanks for your speedy reply Bill. I too, use variacs here quite a bit, but
there's no "secondary" on an autotransformer. Can you kindly give me a few
more details about your variac modifications?
vY 73, Alex, AI2Q in Kennebunk, Maine .-.-.
----------
From: William L. Fuqua III
To: Alex Mendelsohn
Subject: Re: 30 Amps needed
Date: Friday, April 18, 1997 3:33PM
I usually never have a shortage of filiment transformers.
I pick up old variacs and wind my own secondary using the old
variac core and winding (primary). On the larger variacs it
takes about 2 to 3 turns per volt. If I decide to change
amplifer tube types I just rewind the secondary I put on the variac.
73
Bill
At 02:24 PM 4/18/97 -0600, you wrote:
>
>Hello all:
>
> Is there anyoine out there that has a 30 A at 5 V filament
>transformer they'd like to part with? I just finished building a pair of
>4-400As in a dedicated 160 meter amplifier, and the transformer I've got in
>there now is running warm; it's a tad overloaded.
>
>Any help would be appreciated.
>
>Many thanks es vy 73, Alex, AI2Q in Kennebunk, Maine .-.-.
>
>
William L. Fuqua III P.E. E-mail WLFUQU00@POP.UKY.EDU Phone (606)
257-4155
Department of Physics and Astronomy CP-177 Chem. Phys. Bldg.
University of Kentucky , Lexington, Ky 40506-0055
Date: Fri, 18 Apr 1997 23:33:02 +0000
From: Sandy W5TVW <ebjr@worldnet.att.net>
Subject: Trouble!
Sorry for this. Anybody had anything directed my way today, try it
again!
My hard drive barfed on me!
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**
**Butternut HF2V antenna, G-R test gear.....................***
Date: Sat, 19 Apr 1997 07:07:52 +0000
From: "Brian Carling (Radio G3XLQ / AF4K)" <bry@mnsinc.com>
Subject: 300 watts out on 40m
Did anyone else see the design for a 300-500 watt CLASS-E
amplifier shown in QST this month?
Seems like it would be just what we are looking for to clear the
ether when the SSB boys show up and jam the frequencies below 7060
kc.
OK, I know it is solid stats, but with such a small parts count and
low cost, it might be a reasonable quick & easy alternative for a few
of us out here!
73 - de AF4K, Bry
********************************************************
*** 73 from Radio AF4K / G3XLQ in Gaithersburg, MD USA *
** E-mail to: bry@mnsinc.com *
*** See the great ham radio resources at: *
** http://www.mnsinc.com/bry/ *
********************************************************
Date: Sat, 19 Apr 1997 07:07:58 +0000
From: "Brian Carling (Radio G3XLQ / AF4K)" <bry@mnsinc.com>
Subject: Re: FW: HQ-120
On 18 Apr 97 at 17:23, Alex Mendelsohn spoke about FW: HQ-120 and
said:
>
> Hi Eric and nice to meetcha!
>
> I use a 6L6 colpitts oscillator on 80 and 40. It usesa Type 80
> rectifier for some semblence of authenticity and a VR-150 on the
> screen. No chirp, but I can "pull" the freq. with my hand on the
> plug-in coil. That's great fun when signing off.
He he - I will have to try that here!
I can do the same pulling, while putting my hand near the crystal on
some of my open-chassis QRP tube xmtrs, he he!
> BTW: the schematics for my rigs are available as OrCAD files, and
> are posted on one of the glowbug web sites; I forget which one.
>
> Vy 73, Alex, AI2Q in Kennebunk, Maine .-.-.
What web sites????
They weren't in the message & I would like to see them!!
Thanks - Bry, AF4K
********************************************************
*** 73 from Radio AF4K / G3XLQ in Gaithersburg, MD USA *
** E-mail to: bry@mnsinc.com *
*** See the great ham radio resources at: *
** http://www.mnsinc.com/bry/ *
********************************************************
Date: Sat, 19 Apr 1997 07:13:30 +0000
From: "Brian Carling (Radio G3XLQ / AF4K)" <bry@mnsinc.com>
Subject: Re: Fast xtal delivery!
Nothing wrong with a dipole Tom!! I look forward to hearing that 6T9
rig!
Am planning to eventually build up this 6GW8 rig here myself!
Also have some 6BM8 so I am well fixed for triode-pentode power QRP
chirpers!
I am sending in my crystal order this week to John, so will look for
you on the now-standard xtal frequencies he is producing for us!
72.5 - Bry, AF4K
p.s. NOTE: Please post your messages to the new GB list at:
glowbugs@www.atl.org
and not just theporch. Thanks!
On 18 Apr 97 at 17:57, Tom R. Rice spoke about Fast xtal delivery!
and said:
> Surprise! In the mailbox this morning was found
> a package from Phoenix Crystals with my 40-meter
> set. Pretty durned good service, I'd say, as I mailed
> the order on April 4th.
>
> Gimme a few more days to get the 6T9 rig finished
> and there'll be some gb activity from out here in
> CA land, even if with just a li'l ole dipole.
>
>
> --
> "It's lots of fun having fun, even if you don't enjoy it!"
> -- Gracie Allen
> Tom R. Rice
> tomrice@netcom.com
> CIS: 71160,1122
>
********************************************************
*** 73 from Radio AF4K / G3XLQ in Gaithersburg, MD USA *
** E-mail to: bry@mnsinc.com *
*** See the great ham radio resources at: *
** http://www.mnsinc.com/bry/ *
********************************************************
Date: Sat, 19 Apr 1997 07:56:16 -0400
From: Adam Liette <kb8ydx@geocities.com>
Subject: XTAL Probs
Before I order some crystals, I want to try to find out what size or number
or what ever the can is.
Across the top is abt 1 in. and abt maybe an inch and 1/4 tall.
Looks just like the xtals commonly used in 11m sets. Just about
5 times larger. I'm wanting to try and pull a gov't rig (39.58)
to 6m (52.525 call).
It's a big tube GE rig. Think a label inside says it was last serviced in
'67. I couldn't find a model number. It was used by the Ohio DOT i THINK.
Not sure. Somethng on 39.58. Might be a good reason for me to get on 6m FM
if possible. I'd barely have any cash invested. I bought the thing fer $7
at an auction.
I LOVE AUCTIONS! I lucked out. The woman having the auction was the wife of
our one-time Police Cheif. Oh well.
Any Help Appreciated. TNX!
Adam Liette
URL:kb8ydx.base.org
E-Mail:kb8ydx@geocities.com
- --------- --------
/ |
/ ----| / ___
/ | |___
/ -------- ___|
Date: Sat, 19 Apr 1997 18:58:32 +0000
From: Sandy W5TVW <ebjr@worldnet.att.net>
Subject: Sell/Swap: Odds-N-Ends
**************** More "Odds-N-Ends"for sale (AGAIN)(REVISED)*************
Following items for sale or trade. Most items are "vintage radio/
boat anchor" items from the vacuum tube era!! Some prices readjusted
from previous post. I need to move it all out! (To make room for
newer "old" stuff, of course!)
BRITISH "AVO 8" Mk III Multimeter. Very accurate! Works very
well, with resistance range extension unit and instruction/
service manual (copies). Cosmetically VERY nice except for
one hairline crack in meter glass window. (Does not affect
operation!) This is the British "Roll-Royce" version of the
Simpson 260! With additional "Resistance range extension unit"
(Originally cost $95 alone!) BEST OFFER over $125! or TRADE?
EICO 377 Sine/square wave generator. Covers 20 to 200,000 Hz in
4 ranges continously. (Not 'step' tuning) working OK. Case needs paint.
With photocopy of manual. $15 plus shipping/packing.
SIDEBAND ASSOCIATES SBA-312 Commercial Xtal controlled SSB trannsceiver.
With crystals for 2,4,6,8,12, and 16 Mhz channels (Some old simplex marine
frequencies) It runs 100 watts out and is semi-solid state. (Transmitter
uses a pair of 6KD6 tubes) 115 VAC power supply built in. Photocopy of
book, no mike. Cosmetically good, a few scuffs, needs to be
cleaned up. Worked OK last time used. (was an 'antenna tuner'
test RF source in the shop I used to work in.) $75 plus shipping/packing.
HEWLETT PACKARD 614A and 616A RF Generators. The 614 covers 780-2200
Mhz and the 616A covers 1750-4400 Mhz. The 614A works fine last time
I tried it! The 616A has a bad power transformer (I think) and needs
some tubes (Tubes still in the RF cavities though!) I must get these
out from underfoot! $10 for BOTH to the first person to show up and
pick them up! New Orleans area. I must move these out.
LAMPKIN model 105B Frequency Meter. No documents. Works. Cosmetically
good. $15 plus shipping.
The following tubes: All are NOS except as marked. (Prices negotiable)
34 ea. 25Z5G, 19 ea 14A7, 2 ea. 14B6, 6 ea. 14C5, 3 ea 14F7, 10 ea. 14H7,
10 ea. 14R7, 1 ea. 14AF7, 1 ea. 7A8, 1 ea. 7B6, 1 ea. 7B7, 1 ea 7B8, 15 ea.
7C5, 1 ea. 7Q7, 1 ea (pull-out) 8122, 8 ea. 8156, 6 ea. 4657, 2 ea 8560, 6
ea 7984,
5 ea. 5894, 13 ea. 1625 (some new, some pull-outs), 5 ea 12GE5, 9 ea. 6080,
6 ea. ECH35, 2 ea 6528, 1 ea. 4-125(pull-out), 2 ea 4E27.
I am open to trades. WHAT HAVE YOU?
Looking for General Radio test equipment,
Hallicrafters:SX-71 receiver, S-76 receiver, SX-100 receiver.
B&W "TVL" or "HDVL" coils for 160, 80, 40 meters
+ Jackbar and swinging link assy. to match.
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**
**Butternut HF2V antenna, G-R test gear.....................***
Date: Sat, 19 Apr 1997 19:10:03 -0500 (GMT-0500)
From: Mike Toneri <toneri@ils.net>
Subject: Re: 300 watts out on 40m
At 07:07 AM 4/19/97 +0000, Brian Carling (Radio G3XLQ / AF4K) wrote:
>Did anyone else see the design for a 300-500 watt CLASS-E
>amplifier shown in QST this month?
>
>Seems like it would be just what we are looking for to clear the
>ether when the SSB boys show up and jam the frequencies below 7060
>kc.
>
>OK, I know it is solid stats, but with such a small parts count and
>low cost, it might be a reasonable quick & easy alternative for a few
>of us out here!
>
>73 - de AF4K, Bry
How about if I just switch the Viking 500 to 7050 or better still, use the
Thunderbolt?
73...Mike VE3FGU
***************************************************
Mike & Lynda Toneri E-mail: toneri@ils.net
***************************************************
End of glowbugs V1 #11
**********************
Created by Steve Modena, AB4EL
Comments and suggestions to modena@SunSITE.unc.edu