Ham Radio/Ham Radio CD-ROM (Emerald Software) (1995).ISO/news/ih91250a/ih91251.txt

Internet Message Format | 1991-03-29 | 29KB

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Subject: Info-Hams Digest V91 #251
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Info-Hams Digest            Fri, 29 Mar 91       Volume 91 : Issue 251

Today's Topics:
                       "Business use" and MARS
             a few fundamental questions about RF signals
                 Antenna matching problem for novice
                        ATV: AM or FM (2 msgs)
            Can you really learn code from tapes? (2 msgs)
                           mods for HR2600
                       Re: First No-code Tech?
                        STS-37 SAREX Timeline
                the Freeband below 10 meters (2 msgs)
     Vacuum tube question/quest (Attn: OOTs & gov't surplus fans)
                     WRISTWATCH 2m TRANSCEIVER ?

Send Replies or notes for publication to: <[e-mail]>
Send subscription requests to: <[e-mail]>
Problems you can't solve otherwise to [e-mail].

Archives of past issues of the Info-Hams Digest are available
(by FTP only) from UCSD.Edu in directory "mailarchives/info-hams".

We trust that readers are intelligent enough to realize that all text
herein consists of personal comments and does not represent the official
policies or positions of any party.  Your mileage may vary.  So there.
----------------------------------------------------------------------

Date: 29 Mar 91 16:51:44 GMT
From: [e-mail]
Subject: "Business use" and MARS
To: [e-mail]

[e-mail] (Will Martin) writes:

> Is MARS traffic subject to less restrictions regarding content than
> ordinary or regular ham radio? For example, postulate a husband-and-wife
>
> Am I wrong in these impressions (either one or both)? If so, please post
> corrections...

Although rules and practices may have changed recently (doubtful), when I was
active in USAF MARS, the rules regarding permissable message content were AT
LEAST as strict as those in ham radio.

The major difference that I liked and which is what the rule for amateur
automatic packet traffic SHOULD be, but isn't, is that message content was
not reviewed for propriety at each relay point in the path from station of
origin to destination. With the single exception of death notifications, any
improper message was delivered anyway BUT THE OPERATOR WHO PERMITTED IT TO
ENTER INTO THE SYSTEM IN THE FIRST PLACE WAS SEVERELY DISCIPLINED.

It should not be lost sight of that MARS is NOT a funny kind of ham radio
named after a candy bar. MARS is a military system in which amateurs are
permitted a secondary role. Hence, the 'handle' HQ has on rule enforcement
would probably make the FCC drool with envy.

------------------------------

Date: 28 Mar 91 20:50:34 GMT
From: hpl-opus!hpnmdla![e-mail]
Subject: a few fundamental questions about RF signals
To: [e-mail]

In rec.radio.amateur.misc, [e-mail] (Chuck Harris - WA3UQV) writes:

>In article <[e-mail]> [e-mail] (Perry G Ramsey) writes:
>>In article <[e-mail]>, [e-mail] (kyongsok kim) writes:
>>> I wonder if the
>>> same RF signal can travel either through copper wire or through air.  In
>>> other words, is there no difference between RF signal (say, for channel
>>> 4) that my TV receives from the air and RF signal (say, for channel 4)
>>> coming from CATV company through cable?

>>
>>None at all, except that one is an electromagnetic wave traveling through
>>the air and the other is an alternating current traveling through a
>>wire.

>I'm sorry Perry, but you are wrong.  The "signal" travelling thru the coax
>is an electro-magnetic wave.

The signal traveling from your flashlight battery to the bulb is also
technically an electro-magnetic wave.  When the switch closes, the lamp
doesn't get its voltage for about 1/4 nanosecond.

AL N1AL

------------------------------

Date: 29 Mar 91 14:18:40 GMT
From: swrinde!elroy.jpl.nasa.gov!usc!wuarchive!uwm.edu!linac!att!att!tsdiag![e-mail]
Subject: Antenna matching problem for novice
To: [e-mail]

In article <[e-mail]> [e-mail] (Paul Landolt) writes:
-I am having trouble with matching an antenna and would like a bit of help.
-I am studying for my amateur license, and so I am just trying to get a handle
-on these things.
-
-I had bought an antenna that was 'percisly matched at the factory".  So, this
-is a fibreglass, top-load antenna with a 10ft cable (the whole mess is set for
-an impedence of 50 ohms).  I remember in my readings that the antenna cable
-becomes part of the antenna (for the sake of matching/tuning), and that
-changing the cable length with change the match.

Most of the time, this is _not_ true.

-My question is:  How would I match the impedance if I changed the cable length?
The cable length generally has little to do with the SWR of the antenna. The
type and quality of the cable can make a difference, though. Note that coax
exhibits the same characteristic impedance regardless of length/frequency.

-...Do I need to get a SWR meter and a matching box? Add
-some Impedence matching resistors to the line? (Radio Shack sold an 8hm, 20W
-one).  Is there a set formula for calculating the resitance needed to re-match
-the line?

Adding resistors to the line can help the apparent impedance I suppose, but
it would just waste power that could be radiating signal otherwise.  By
using an SWR meter you can adjust the length of the antenna to get a near
perfect match without resorting to resistors. Find an SWR meter and give
it a try.  I hope this information is helpful.
--
David E. Tiller         [e-mail]  | Concurrent Computer Corp.
FAX:  [phone]      Ph: [phone] (w) | 2 Crescent Place, M/S 117
UUCP: ucbvax!rutgers!petsd!tsdiag!davet        | Oceanport NJ, 07757
ICBM: 40 16' 52" N      73 59' 00" W           | N2KAU @ NN2Z

------------------------------

Date: 29 Mar 91 15:10:52 GMT
From: usc!zaphod.mps.ohio-state.edu!wuarchive!udel!haven!wam.umd.edu![e-mail]
Subject: ATV: AM or FM
To: [e-mail]

In article <[e-mail]> [e-mail] (Phil Howard KA9WGN) writes:
>Some of the ATV equipment on the market for 23cm uses FM instead of AM or
>VSB as its modulation.
>
>I'd like to know what the merits in doing this are.  I note that the ARRL
>bandplan for 23cm includes 5 "channels" for ATV that are only 6 MHz wide.
>
>One maker of FM equipment tells me that the picture is a lot less noisy
>and the bandwidth is the same as AM.  I don't see how the picture can be
>a lot less noisy.  FM gets its advantages when the deviation is high enough
>that noise will not (at a detectable level) modulate the phase of the
>carrier since the amplitude is constant after limiting.
>
etc...etc....
>
>FM audio as we typically use it on VHF and UHF now days involves a
>deviation of only (peak) 5 kHz, a bandpass of 3 kHz, and an interstation
>spacing of perhaps 60 kHz (based on close repeaters in a "dense" area).
>This gives us audio that, if strong enough, is relatively free of noise,
>but is readily interferred with by cochannel signals, and has the sound
>of "frying" when weak.
>

>Translating this to video results in 7 MHz of deviation and an interstation
>spacing of about 84 MHz!
>

Television point to point links and ENG (Electronic News Gathering) uses
a P-P deviation of 8 MHz for a 1 V RMS sine wave (Video is 1 V sync tip
to peak) with CCIR rec 405 pre-emphasis (which in NTSC cuts 10dB at the
low end and adds 2 dB at the high end (crossover at 761 kHz)).
My guess is that FM gives an advantage at the low frequency end (which incude
of course the sync signals) (where the modulation index is high).
The eye is less sensitive to high frequency noise and the pre-emphasis
helps there.

Satellite TV transmission uses FM also (Full transponder is 30 MHz BW &
I think the deviation is about 17 MHz + dispersion)

>Yet I am told by the maker of the FM equipment that the signal takes no
>more room than an AM signal.
ENG channels are 17 MHz apart (But there are split channels)
>
etc... etc....
>
>Another aspect of FM that bothers me a lot is the fact that, as the signal
>gets weaker and weaker, the quality of the resultant signal drops even
>faster.  The point at which AM and FM equal out will probably be a noisy
>picture, but below that, FM declines very rapidly.

S/N for an 8 MHz p-p deviated signal and CCIR pre-emp (NTSC)
is equal to Pr - n + 128.6

where Pr is the receivecd level in dBm, n is the noise figure in dBs
& the 128.6 is the fudge factor which accounts for the conversion units,
pre-emphasis, FM improvement factor etc...

I've not looked into VSB or AM much so I can't give the figures for that
but perhaps someone else out there has the formula.

--
Michael Katzmann  (VK2BEA/G4NYV/NV3Z)   Please email to this address |
Broadcast Sports Technology                                          |
2135 Espey Ct. #4                                                   \|/
Crofton MD 21114-2442    [phone]      ...uunet!opel!vk2bea!michael

------------------------------

Date: 29 Mar 91 15:19:15 GMT
From: pa.dec.com!shlump.nac.dec.com!sousa.enet.dec.com!sndpit.enet.dec.com![e-mail]
Subject: ATV: AM or FM
To: [e-mail]

In article <[e-mail]>, [e-mail] (Phil Howard KA9WGN) writes...
>Some of the ATV equipment on the market for 23cm uses FM instead of AM or
>VSB as its modulation.
>
>I'd like to know what the merits in doing this are.  I note that the ARRL
>bandplan for 23cm includes 5 "channels" for ATV that are only 6 MHz wide.

I saw (was it here on the net?) a wider channel (12 MHz?) in one of the
higher bands for FMTV, so I suspect it takes more bandwidth.  I'm told that
the standard for FM ATV deviation is some 16(?) MHz, giving something like
50 MHz bandwidths [using BW=2(dev+Fmax)].  This gives _really_ nice
pictures, or so I'm told, but it really chews up bandwidth.

On the other tentacle, satellite TV bandwidths are something like 10 MHz,
including a couple of sound carriers and a digital link, and those are FM,
so it must work in narrower bandwidths.

>Yet I am told by the maker of the FM equipment that the signal takes no
>more room than an AM signal.

I think I've talked to the same vendor.  His message seems to be "Set the
deviation so the main carrier takes up the full 6 MHz of allocated
bandwidth and don't worry about (or let others worry about) the sidebands."
I might be getting some FMTV gear in the next couple of months, (anything
has to be better than the AMTV gear I've seen advertized), and I'll be
trying different deviations, bandwidths, and powers, so hopefully I'll have
some real numbers to talk about.  But it does sound like when I cut the
deviation way down like that I'll be getting lower (than optimum) picture
quality and losing the 'capture effect' (which apparently depends on the
deviation being larger than the highest-modulating-frequency).  The quick
answer seems to be that nobody knows....

>Filtering these sidebands off will be the next trick.

I'm not sure you _can_ filter them off, they aren't just unwanted spurs,
they are sidebands of your signal, and if you filter them off your main
carrier will be distorted in some way.  I don't know, and I can't find
anyone who knows, so I'm going to go ahead and try it out and determine
what's the minimum usable abndwidth and deviation for FMTV.

Willie Smith
[e-mail]
[e-mail]
{Usenet!Backbone}!decwrl!sndpit.enet.dec.com!smith

------------------------------

Date: 28 Mar 91 18:48:10 GMT
From: hpl-opus!hpspdra![e-mail]
Subject: Can you really learn code from tapes?
To: [e-mail]

> Re. learning Morse.
> Has anyone found teaching tapes that useful?

The big advantage of tapes of course is that many of us can listen to
them during a drive to work (I suppose this is un-quality time in the
modern vernacular).
Anyway I like my good old DATONG morse tutor.
DATONGs are very common in G-land but rare stateside (probably because
they don't teach the pro-signs).   DATONGs do however have the advantage
of being small, self contained and the battery lasts for ages so they
are a lot more convenient than a PC.   I suppose some people use a
laptop for Morse practice?
---------------------------------------------------------------------------
Henry Black (G4NOC,KK6JR)  [phone]  [e-mail]  KK6JR @ W6PW-3

------------------------------

Date: 28 Mar 91 21:06:08 GMT
From: hpfcso!hpfcdc![e-mail]
Subject: Can you really learn code from tapes?
To: [e-mail]

>I have found that I am almost 100% efficient at copying the random groups
>from Morse Tutor at 13 wpm, but I am terrible at copying QSO.  I think it comes
>from the fact that random groups aren't interesting to listen to, so
>the brain takes them one character at a time.  OTOH, QSO's have content
>which is absorbed and interpreted.  It's a slightly different mental
>process.
>
>Perry G. Ramsey           Department of Earth and Atmospheric Sciences


Well, there you go again.  Letting your brain get in the way of
copying CW.  Take your brain out of your head, and set it on the
table before listening to code.

This works much better for me, although I occasionally forget to
put my brain back in.


:-)

Perry / KF0CA

------------------------------

Date: 28 Mar 91 20:43:36 GMT
From: hpl-opus!hpnmdla![e-mail]
Subject: mods for HR2600
To: [e-mail]

In rec.radio.amateur.misc, [e-mail] (Alan Larson) writes:

>In article <[e-mail]> [e-mail] (Doug Faunt N6TQS 415-688-8269) writes:
>>Look in the April 1991 issue of 73, page 59, middle of right hand
>>side.  ChipSwitch, 4773 Sonoma Hwy., Suite 132, Santa Rosa CA
>>95409-4269, is selling a replacement CPU for 2510's and 2600's for
>>$60.  I don't know if they're real or not.

>  Did I miss something?  Why replace the CPU for a 2510 or 2600?  I
>would think replacing the ~15 kHz wide IF filter would be a better
>thing to do.

The CPU has the personality of the radio burned into its internal PROM.
By replacing the CPU, you can add features.

They are selling like the proverbial hotcakes.  I hear they sold 5,000
units by "word of mouth" even before the first 73 ad.

AL N1AL

------------------------------

Date: 28 Mar 91 17:19:09 GMT
From: hpfcso!hpfcdc![e-mail]
Subject: Re: First No-code Tech?
To: [e-mail]

> She was getting licensed so that she could talk to her husband -- not
> because she loves radio.

You are framing it negatively when it you be positive.  Instead of:

    "the new rule will bring in people whose interest is trivial"

try:

    "the new rule will attract people who would not otherwise have been
    interested enough to be exposed to the experience"

------------------------------

Date: 29 Mar 91 16:43:37 GMT
From: [e-mail]
Subject: STS-37 SAREX Timeline
To: [e-mail]

Now that STS-37 is only a week before lift off, its time to think seriously
again about working or at least monitoring SAREX activity from the space craft.
Therefore, I've converted the previously published operating schedule into a
form that can be easily updated with accurate time of launch and then converted
into real UTC dates and times. The table below is an example of the posting I
will make right after lift off. It uses a lift off time of April 5 at 14:18 UTC.
The table that will be posted after lift off will, of course, contain the real
lift off time, and all other times will be adjusted accordingly. Reading left
to right, Mission Elapsed Time in Days, Hours, and Minutes, UTC date and time
in Day of the Month, hours, and minutes, and then Event. Note that the entry in
the UTC D column is Day of the Month; so, for example, the first entry under
UTC, 5 14 18, should be read as April 5 at 14:18 UTC. Also, be aware that
Daylight Savings Time will begin during this mission. Don't let that confuse
you. All times shown here are UTC which does not shift back and forth with the
passing of the seasons. Time line information for this table comes from
"STS-37 SAREX Information Summary" posted by Gary Morris (N5QWC) on 21 March,
1991.
Good luck to all.

-------------------------------------------------------------------------------
| Anything can occur                             | Joseph M. Fedock           |
| Anything is possible and likely                | N3IE                       |
| Duration and space do not exist                | Unisys DS,Inc/EISG/VFL     |
| On the tenuous ground of reality               | Paoli, PA 19301            |
| Imagination spins out and weaves new patterns  | [phone]             |
|   -  "Fanni and Alexander" - Ingmar Bergman.   | [e-mail]    |
-------------------------------------------------------------------------------


 MET           UTC
  D  Hr  Mn     D  Hr  Mn   Event
  -  --  --     -  --  --   ------------------------------------
  0   0   0     5  14  18   Launch
  0   6  55     5  21  13   Start_SAREX_Setup
  0   7   0     5  21  18   Begin_Pre-Sleep_Activity
  0   7  20     5  21  38   Finish_SAREX_Setup
  0  10   0     6   0  18   Begin_Sleep_Period
  0  18   0     6   8  18   Begin_Post-Sleep_Activity
  0  21   0     6  11  18   End_Post-Sleep_Activity
  0  21  50     6  12   8   Cabin_depress_to_10.2_PSI
  0  23  12     6  13  30   AOS_FSTV_w/N9AB,_US_Bridge
  0  23  30     6  13  48   LOS_FSTV_w/N9AB,_US_Bridge
  1   0  51     6  15   9   AOS_School_#1_via_US_Bridge
  1   1   9     6  15  27   LOS_School_#1_via_US_Bridge
  1   2  29     6  16  47   AOS_School_#2_via_US_Bridge
  1   2  47     6  17   5   LOS_School_#2_via_US_Bridge
  1   4   9     6  18  27   AOS_School_#3_via_US_Bridge
  1   4  25     6  18  43   LOS_School_#3_via_US_Bridge
  1   6   0     6  20  18   Begin_Pre-Sleep_Activity
  1   6   0     6  20  18   AOS_School_#4_via_SA_Bridge
  1   6  21     6  20  39   LOS_School_#4_via_SA_Bridge
  1   9   0     6  23  18   Begin_Sleep_Period
  1  17   0     7   7  18   Begin_Post-Sleep_Activity
  1  20   0     7  10  18   End_Post-Sleep_Activity
  1  21   0     7  11  18   GRO_Grapple
  1  21  10     7  11  28   GRO_Unberth
  1  22  10     7  12  28   GRO_Solar_Array_Deploy
  1  23  30     7  13  48   GRO_High_Gain_Antenna_Deploy
  2   0  11     7  14  29   AOS_FSTV_w/W5RRR,_KE4PT_w/US_Bridge
  2   0  31     7  14  49   LOS_FSTV_w/W5RRR,_KE4PT_w/US_Bridge
  2   3  10     7  17  28   GRO_Release
  2   6   0     7  20  18   Begin_Pre-Sleep_Activity
  2   9   0     7  23  18   Begin_Sleep_Period
  2  17   0     8   7  18   Begin_Post-Sleep_Activity
  2  20   0     8  10  18   End_Post-Sleep_Activity
  2  20   0     8  10  18   Begin_EVA_Prep
  2  21  50     8  12   8   Unscheduled_SSTV/Packet
  2  22  15     8  12  33   Airlock_Depress/Egress
  2  23  20     8  13  38   Unscheduled_SSTV/Packet
  3   0  50     8  15   8   Unscheduled_SSTV/Packet
  3   2  20     8  16  38   Unscheduled_SSTV/Packet
  3   4  30     8  18  48   Airlock_Ingress/Repress
  3   5  15     8  19  33   Begin_Pre-Sleep_Activity
  3   8  15     8  22  33   Begin_Sleep_Period
  3  15  15     9   5  33   Begin_Post-Sleep_Activity
  3  18  15     9   8  33   End_Post-Sleep_Activity
  3  18  15     9   8  33   Cabin_repress_to_14.7_PSI
  3  22  54     9  13  12   AOS_School_#5_US_Bridge
  3  23  13     9  13  31   LOS_School_#5_US_Bridge
  4   0  32     9  14  50   AOS_Backup_FSTV_or_w/W5RRR_US_Bridge
  4   0  52     9  15  10   LOS_Backup_FSTV_or_w/W5RRR_US_Bridge
  4   5   5     9  19  23   Begin_Pre-Sleep_Activity
  4   5  10     9  19  28   Start_SAREX_Stow
  4   5  40     9  19  58   Finish_SAREX_Stow
  4   8   5     9  22  23   Begin_Sleep_Period
  4  16   5    10   6  23   Begin_Post-Sleep_Activity
  4  19   5    10   9  23   End_Post-Sleep_Activity
  4  23   5    10  13  23   Deorbit_Burn
  5   0  10    10  14  28   EDW_Landing

------------------------------

Date: 27 Mar 91 21:46:29 GMT
From: hpfcso!hpfcdc![e-mail]
Subject: the Freeband below 10 meters
To: [e-mail]

>I think that what is happening between 28.000 and 28.100 is truly
>disgusting, but what can we do about it??


I'm glad someone else is unintentionally QRMing the freebanders on
our frequencies.  It's funny how 10 meters works.  A completely quiet
frequency one minute, then the next minute the conditions change and
bring in a freebander at S9.

I was calling CQ on an otherwise quiet frequency.  These freebanders pop
in (QSK is nice, ain't it ?), and then suddenly QRT.  Well, not wanting
to interfere, I moved up 10 KHz, and sonofagun if it didn't happen
again.  Yup, 10 meters is really a strange band.

Maybe we need to put beacons and packet in 28.005 - 28.95, every 5 KHz.
It's time to get militant and take our bands back.

Perry / KF0CA

------------------------------

Date: 28 Mar 91 21:14:32 GMT
From: hpfcso!hpfcdc![e-mail]
Subject: the Freeband below 10 meters
To: [e-mail]

>If I had my dream come true, the FCC would hire engineers on a commision basis.
>A team of monitoring stations could sweep into a small city and collect
>measurements and video tape the whole deal for a few days, they could send
>evidence in to a judge with the proper authority to give them whatever
>warrant they need, raid them and collect a percentage of the $1000 fines
>
>Luigi Giasi KA1UTU


Better yet, CQ magazine could sponsor a DF contest for the freeband.
The ensuing turkey shoot would be most entertaining.

Or, maybe the FCC should turn the freeband into a free-for-all band.
Jungle rules.  No power limit.  Consider it a place for linear amplifier
and antenna melting-point experimentation beyond the 1500 watt level.

:-)

Perry / KF0CA

------------------------------

Date: 29 Mar 91 03:38:29 GMT
From: bloom-beacon!snorkelwacker.mit.edu!spool.mu.edu!uwm.edu!cs.utexas.edu!oakhill!nddsun1![e-mail]
Subject: Vacuum tube question/quest (Attn: OOTs & gov't surplus fans)
To: [e-mail]

In article <[e-mail]> [e-mail] (Geoffrey S. Mendelson) writes:

>I believe tube numbers were standardized in the 30's with us numbers being

>nTTxxm

>n being the number of elements (including the filament) therefore:
>diodes were 3, triodes were 4, etc, dual triodes were 7.

Not quite, n is the filament voltage. There existed for example a 5L6,
6L6, 12L6 and I even HAD a 7L6GTB! (A "locktal" socket no less :-) )

THe standard was followed pretty well for common radio/TV recieving
tubes, but as you point out got hairy with "industrial/transmitting
types. For example the 807 was a 6L6 with a top anode connector and 5
pin "jumbo" socket rather than an eight pin "octal" socket. The 1625 was
the 12 volt filament version of the 807.

The 6l6 was fine for audio work, but the anode capacitance was too high
for RF which is the reason for the 807/1625.

--
           *Mike Waters    AA4MW/7  [e-mail] *
Endless Loop: n., see Loop, Endless.
Loop, Endless: n., see Endless Loop.
        -- Random Shack Data Processing Dictionary
--
           *Mike Waters    AA4MW/7  [e-mail] *
Endless Loop: n., see Loop, Endless.
Loop, Endless: n., see Endless Loop.
        -- Random Shack Data Processing Dictionary

------------------------------

Date: 29 Mar 91 07:41:15 GMT
From: fernwood!portal!apple!xanadu![e-mail]
Subject: WRISTWATCH 2m TRANSCEIVER ?
To: [e-mail]

In article <[e-mail]> [e-mail] (Jeff Later) writes:
>
>How close are we?!  I presently own an Icom 2sa, which does an incredible
>amount of stuff for it's petite size!  In fact, with the battery removed
[stuff deleted..]
>Is ANY manufacturer of Ham equip.
>thinking along similar lines, or have I just been watching too many 007
>re-runs??

Sony *already* has a 6-meter FM wrist transceiver.....well actually forty
nine mhz; single frequency.  And yes the power/range is limited.  To bad
there aren't any repeaters for that band....

[lots of smileys here]

Incidently, the TH27 is also very small with the battery out --mostly
air in there without the battery.

I don't really want a wrist transciever; I want a glasses frame transceiver!
With frequency readout in the upper right hand corner of one of the lenses!
But the power radiated would have to be real low (like I'm sure I'll already
get headaches just listening, let alone transmitting).

Jeff

------------------------------

Date: 29 Mar 91 17:44:19 GMT
From: swrinde!zaphod.mps.ohio-state.edu!think.com!paperboy!hsdndev!dartvax!eleazar.dartmouth.edu![e-mail]
To: [e-mail]

References <[e-mail]>, <[e-mail]>, <[e-mail]>
Subject : Info on new Ten Tec HF Rigs (Esp. QRP Model)


(First time posting, please be patient...)

I'm interested in trying QRP on HF.  A while ago I heard that Ten Tec was
introducing a 5W max power rig.  Has this radio been introduced yet, has
anyone had experience with it and are there any good sources for QRP
information?

Thanks in advance.

73 de N1EMF  (Bill W.)

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Date: 29 Mar 91 17:21:03 GMT
From: agate!stanford.edu!neon.Stanford.EDU![e-mail]
To: [e-mail]

References <[e-mail]>, <[e-mail]>, <[e-mail]>
Subject : Re: Vacuum tube question/quest (Attn: OOTs & gov't surplus fans)

In article <[e-mail]> [e-mail] (Mike Waters) writes:
>In article <[e-mail]> [e-mail] (Geoffrey S. Mendelson) writes:

->I believe tube numbers were standardized in the 30's with us numbers being

->nTTxxm

->n being the number of elements (including the filament) therefore:
->diodes were 3, triodes were 4, etc, dual triodes were 7.

>Not quite, n is the filament voltage. There existed for example a 5L6,
>6L6, 12L6 and I even HAD a 7L6GTB! (A "locktal" socket no less :-) )

The 'n' value was approximate, and there were exceptions.  The 7.. series
in particular were really 6 (6.3) volt tubes, but with loctal sockets.
Likewise, the 14.. series was 12 (12.6) volt loctal tubes.  A typical AM
radio of the day contained a 12BE6 mixer, 12BA6 IF amp, 12AV6 detector and
audio amp, 50C5 audio power amp, and a 35W4 rectifier.  12+12+12+50+35 = 121.
The filaments were connected in series across the AC line (no transformer).
[schematic from my RCA receiving tube manual].

Marc Kaufman ([e-mail])

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