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- Date: Mon, 7 Mar 94 19:13:10 PST
- From: Info-Hams Mailing List and Newsgroup <info-hams@ucsd.edu>
- Errors-To: Info-Hams-Errors@UCSD.Edu
- Reply-To: Info-Hams@UCSD.Edu
- Precedence: Bulk
- Subject: Info-Hams Digest V94 #260
- To: Info-Hams
-
-
- Info-Hams Digest Mon, 7 Mar 94 Volume 94 : Issue 260
-
- Today's Topics:
- 4-1000A Chimney
- 400 Hz xtal ladder filter, help. (2 msgs)
- ANARTS RTTY NEWS BULLETIN 799 06/03/94
- copying cw on typewriters
- IPS Daily Report 06 03 94
-
- Send Replies or notes for publication to: <Info-Hams@UCSD.Edu>
- Send subscription requests to: <Info-Hams-REQUEST@UCSD.Edu>
- Problems you can't solve otherwise to brian@ucsd.edu.
-
- 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: Mon, 7 Mar 1994 20:22:32 GMT
- From: ihnp4.ucsd.edu!sdd.hp.com!col.hp.com!srgenprp!alanb@network.ucsd.edu
- Subject: 4-1000A Chimney
- To: info-hams@ucsd.edu
-
- Don Turner (don.turner@eabbs.com) wrote:
- : Hi Guys: I need a chimney for my 4-1000A tube. The Eimac part number
- : is SK-506. If any of you are will to let go of one of these, leave a
- : message. .....Don Turner WA6WRX
-
- I know that a Coleman lantern globes work perfectly for 3-1000's. Not sure
- if they work with 4-1000's. They are much cheaper than Eimac chimneys.
-
- AL N1AL
-
- ------------------------------
-
- Date: Mon, 7 Mar 1994 20:33:56 GMT
- From: ihnp4.ucsd.edu!sdd.hp.com!col.hp.com!srgenprp!alanb@network.ucsd.edu
- Subject: 400 Hz xtal ladder filter, help.
- To: info-hams@ucsd.edu
-
- asirene@ntuvax.ntu.ac.sg (asirene@ntuvax.ntu.ac.sg) wrote:
- : Hi,
-
- : My homemade QRP xcvr has a 600 Hz BW xtal ladder filter
- : consisting of 4 12.0000 MHz xtals. However I still find it hard to
- : work pile-ups due to insufficient selectivity. I am planning to
- : change it to 400 Hz. Does anyone know how much improvement I can
- : expect to see? Also, how can this be done in the easiest way? Do
- : I need to add xtal stages or just change to capacitor values?
-
- : 72 es 73,
- : Daniel
-
- ------------------------------
-
- Date: Mon, 7 Mar 1994 20:56:18 GMT
- From: ihnp4.ucsd.edu!sdd.hp.com!col.hp.com!srgenprp!alanb@network.ucsd.edu
- Subject: 400 Hz xtal ladder filter, help.
- To: info-hams@ucsd.edu
-
- : asirene@ntuvax.ntu.ac.sg wrote:
-
- : : My homemade QRP xcvr has a 600 Hz BW xtal ladder filter
- : : consisting of 4 12.0000 MHz xtals. However I still find it hard to
- : : work pile-ups due to insufficient selectivity. I am planning to
- : : change it to 400 Hz. Does anyone know how much improvement I can
- : : expect to see? Also, how can this be done in the easiest way? Do
- : : I need to add xtal stages or just change to capacitor values?
-
- Going from 600 Hz to 400 Hz may not be enough of a change to make
- a significant difference. You might want to shoot for a bit narrower.
-
- I'm assuming the circuit has the capacitors in series between input
- and output with shunt capacitors at input/output and the junctions
- of each pair of crystals. Increasing the capacitance should narrow
- the bandwidth. It will also lower the resonant frequency a bit
- and increase the insertion loss slightly.
-
- Zack Lau (KH6CP) (zlau@arrl.org) wrote:
-
- : ... Increasing the capacitor values will
- : decrease the bandwidth, but will also decrease the impedance.
- : Impedance matching is important to maintain the proper filter
- : shape. ...
-
- To clarify, the load impedance is not really matched to the crystals,
- it is matched to the source. Consider a single-section series crystal
- with no matching capacitors. So long as the crystal series resistance
- is small compared to the load resistance, the crystal has no effect
- on source/load match at resonance.
-
- When you add the shunt capacitors on input/output, you basically have
- added L-networks at both ends, with the crystal providing the required
- series inductance to effect the proper match. (The crystal looks
- inductive above resonance.) The "L-network" transforms the 50 ohm
- source/load impedance down to a lower value, which increases the
- loaded Q of the crystal, narrowing the bandwidth. That also increases
- the insertion loss, which is proportional to (loaded Q) / (unloaded Q).
- The bigger the capacitor, the greater the impedance transformation and
- the narrower the bandwidth.
-
- In the following "schematic", L is the net inductance of the off-resonant
- crystal, and R is the crystal's effective series resistance:
-
- L-network L-network
- |<---------->| |<---------->|
- _______________________
- | |
- Input ------+--|-- L/2 --- R --- L/2 --|--+------ Output
- | |_______________________| |
- | Crystal |
- Input Cap Output Cap
- | |
- Gnd Gnd
-
- AL N1AL
-
- ------------------------------
-
- Date: 7 Mar 94 12:12:44 GMT
- From: nprdc!ihnp4.ucsd.edu!munnari.oz.au!newshost.anu.edu.au!sserve!usage!metro!news.ci.com.au!eram!dave@network.ucsd.edu
- Subject: ANARTS RTTY NEWS BULLETIN 799 06/03/94
- To: info-hams@ucsd.edu
-
- [ ANARTS - Australian National Amateur Radio Teletype Society ]
-
- ANARTS NEWS BULLETIN 799 06/03/94
-
- SUNDAY TRANSMISSION DETAILS.
- 3.545 MHz 0930 UTC This relay is in
- recess until 3rd April.
- 7.045 MHz -3 0030 UTC VK2CTD (Col)
- 14.070 MHz (amtor/fec) 0030 UTC VK2DPM (Alan)
- 14.091 MHz 0030 UTC VK2BQS (JIM)
- 146.675 MHz 0030/0930 UTC VK2JPA (PAT)
- 144.850 MHz (ax25 bbs) VK2JPA AT VK2RWI
- 146.675 MHz (rtty mmbbs/repeater) VK2RTY
-
-
- Views expressed in this news bulletin are not necessarily
- those of the Broadcast Officer, the Relay Officers, or of the
- Society.
-
- Well, did you see us at the Central Coast Field Day? We were
- on the top floor of the stand if you could not find us. I
- believe this happened to other clubs whose displays were on a
- lower floor last year. Shall suggest to the host club that a
- location board be displayed outside the stand main entrance so
- that all club stands can be found more easily next year. It is
- a great location, spacious outlook, but I suppose it is a bit
- hard to get past the refreshment floor, hi hi.
-
- The winner of the Morse Contest held on the ANARTS Stand at
- Wyong last Sunday was VK2IC (he sounds more like a computer
- specialist than a practitioner of the Ancient Art of Morse
- Code). He had two errors in sending and one in receiving. He
- was the proud and pleased recipient of the prizes : the
- President's Bottle(s).
-
- All in all, the day appeared to be a great success -- did you
- meet the IPS team ? There were four on deck during the day. I
- am looking forward to seeing the attendance figures for the
- day. With this new venue, the attendance seems to be spread
- out more, or is it just because there are more places to look
- for people and stands.
-
- We look forward to next year and seeing you all again.
-
- ----------------------------------------
- BARTG Contest
- -------------
- Date: March 19-21 1994, sponsored by the British Amateur Radio
- Teledata Group.
-
- Exchange: Send: RST + QSO number + time in UTC.
-
- Multipliers: Each DXCC country, including first QSO with W, VE
- and VK, counts as a multiplier on each band. Each call
- district in W, VE and VK will count as an additional on each
- band. Also, each continent (6) will count once, not once per
- band.
-
- QSO Points: Count 1 (one) point per QSO.
-
- Final score: Total QSOs x total multipliers x number of
- continents (max 6).
-
- Logs: Use separate logsheets for each band. Logs must show:
- BAND, DATE and TIME (UTC), CALLSIGN, MESSAGE Sent and
- Received, COUNTRIES and POINTS claimed.
-
- Summary sheet must show full scoring, times of operation, and
- address for correspondence.
-
- Logsheets, summary sheets and multiplier and dupesheets are
- all available for copying from the RTTY Contester's Guide,
- published by RTTY Journal.
-
- Deadline: Logs must be received by May 25 to qualify.
-
- Mail logs to:
- BARTG c/o John Barber, G4SKA
- 32 Wellbrook Street
- Tiverton, Devon
- EX165JW, England
-
- Have fun!
-
- ----------------------------------------
-
- IPS weekly report
- -----------------
-
- 24 FEBRUARY - 3 MARCH 1994
- Issue No 09
- Date of issue: 4 March, 1994
-
- INDICES:
- Date 25 26 27 28 01 02 03
- 10cm 097 094 095 093 094 098 101
- A 12 06 06 09 10 17 ( 17 estimated)
- T 71 27 55 57 47 73 64
-
- SUMMARY OF ACTIVITY
-
- Solar activity was very low 25th-26th and 28th February-1st
- March, moderate on 27th, and low on 2nd-3rd March. There was
- an M2 flare on 27th february.
-
- The geomagnetic field at Learmonth (WA) was quiet on 27th,
- quiet to unsettled 26th, 28th-3rd March, apart for a period of
- minor storm activity on 3rd.
-
- Ionospheric F2 critical frequencies at Sydney were uo to 20
- per cent above predicted monthly values on 25th, near
- predicted levels on 26th, near predicted with enhancement
- periods of up to 30 per cent on 27th-1st, and enhanced 10 t0
- 15 per cent on 2nd-3rd March. Sporadic E may have degraded F
- layer communications at times on 1st March.
-
-
- FORECAST FOR THE NEXT WEEK (4 -10 MARCH)
-
- SOLAR: low
-
- GEOMAGNETIC: active-minor storm periods expected March 4-9, due
- to a solar coronal hole.
-
- IONOSPHERIC: degraded HF comms expected March 4-9. Depressions
- of up to 20% may be experienced at times during
- this interval.
-
- Updated IPS Monthly Predicted Smoothed T-indices
- Prepared on Mon Feb 28 12:58:20 1994
- YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC
- ==============================================================
- 1993 42
- 1994 39 37 36 35 34 31 29 27 24 22 21 19
- 1995 19 18 17 16 15 14 14 13 12 11 11 10
- 1996 10 9 9 8 8 7 8 8 9 10 11 12
- 1997 13 14 16 18 20 22 25 28 32 35 40 46
-
- Courtesy of IPS Radio and Space Services
- ----------------------------------------
-
- VK2SG RTTY DX NOTES 25 FEB 94
-
- VK2SG RTTY DXNOTES WEEKENDING 25 FEBRUARY 1994 (BID RTDX0225)
-
- OUR INFORMATION THIS WEEK CAME FROM: 9X5LJ, DJ3IW AND THE
- CENTRAL-EUROPE DX CLUSTER NODE DB0SPC, I5FLN, IK5AAX AND THE
- IK5PWJ PACKET CLUSTER, W2JGR AND THE NJ0M NODE THE TWIN-CITIES
- DX PACKET CLUSTER, W5KSI AND ZS5S. THANK YOU ALL FOR YOUR
- ASSISTANCE.
-
- BANDPASS
-
- FRIDAY 18
- DX NOT SLEEPIN, JUST RESTIN
-
- SATURDAY 19
- 0114-14088 S92ZM 0707-14082 UN7LR
- 1110-21073 5Z4FO FEC 1516-14085 ZS9A
- 1520-21083 8ZD7DP 1527-14088 ER3ED
- 1529-21088 V50CM 1537-14085 5R8DG
- 1542-14087 EX2U 1706-14087 5B4VX
-
- SUNDAY 20
- 0843-21086 9N1AA 0843-21089 9M1AA
- 1045-21086 FR5ZU 1052-21083 TZ6FIC
- 1129-21085 ZD8M 1253-21083 ZD7DP
- 1355-21086 9H1ET 1358-21091 HJ4SAN
- 1401-14086 UT5DX 1407-14084 5B4VX
- 1421-14084 XU7VK 1448-14088 UN7LR
- 1450-14089 YL3FW 1455-21086 5R8DS
- 1627-14084 S59F 1633-14090 5B4ABU
- 1835-14087 ZS1CU 2230-14064 TY1PS CLOVER
-
- MONDAY 21
- 1317-14086 EA8/ON8RI 1720-14083 V31WW
- 2044-14085 V31DV 2044-14090 J88BS
- 2052-14083 ZD7DP 2135-14086 V31EN
- 2209-14085 S92ZM 2156-14085 CO2JJ
- 2330-14085 V31DV
-
- TUESDAY 22
- 0113-14086 V31II 1634-14086 V31WW
- 1814-14087 V31EO QSL KF8NN 1954-14083 J88BS
- 2012-14085 V32GM 2017-14086 CO2KG
- 2019-14082 V31GM 2139-14085 V31MV
- 2339-14083 V31JU
-
- WEDNESDAY 23
- 1620-14088 HK1LAQ
-
- THURSDAY 24
- 0021-14086 CX7BF 2006-14084 ZS0X QSL DJ6JC
-
- NOTES OF INTEREST.
-
- PENGUIN ISLANDS, ZS0 AND WALVIS BAY, ZS9. THE GOVERNMENT OF
- SOUTH AFRICA, AGREED TO HAND OVER THE THIRTEEN PENGUIN ISLANDS
- AND WALVIS BAY, TO THE REPUBLIC OF NAMIBIA ON 28 FEBRUARY.
- DJ6JC, DJ6SI AND V51BI, USING THE CALL ZS0X, SHOULD HAVE BEEN
- ACTIVE ON 23-28 FEBRUARY FROM PENGUIN ISLANDS AND ZS6EZ AND
- G3XTT WITH THE CALL, ZS9Z, FROM WALVIS BAY. THEY BOTH BECAME
- PART OF NAMIBIA BEGINNING 1 MARCH AND MORE THAN LIKELY WILL BE
- DELETED AS DXCC COUNTRIES.
-
- DESECHEO, KP5. THE PLANNED DXPEDITION BY A GROUP OF OPERATORS
- FOR 1-7 MARCH, HAS BEEN CANCELLED. PERMISSION TO LAND HAS BEEN
- DENIED BECAUSE A GROUP OF HAITIAN SQUATTERS. UNTIL THIS CAN BE
- RESOLVED, NO LANDING PERMISSION CAN BE GIVEN.
-
- REVILLA GIGEDO, XF4. THIS OPERATION WAS ON UNTIL 4 MARCH.
- QSL HECTOR, XE1BEF.
-
- MAYOTTE, FH. HERMANN, DJ2BW SHOULD BE SIGNING FH/DJ2BW FOR A
- MUCH NEEDED ONE IN RTTY FROM 1-9 MARCH. KYFC
-
- FOR NEXT WEEK'S BULLETIN, SEND YOUR BANDPASS AND NOTES OF
- INTEREST TO JULES, W2JGR AT W2TKU.#SRQ.FL.USA.NA
-
- REMEMBER, DX DON'T SLEEP.
- GL DE BOB, WB2CJL AT W5KSI.NOLA.LA.USA.NA
- ---------------------------------------
-
- Coming events
- -------------
- 1994
- March 19th-20th BARTG WW RTTY Contest
-
- April 16th-17th SARTG WW AMTOR Contest
- ------------------------------------
-
- Society information
-
- The Society may be contacted at : PO Box 860, Crows Nest 2065
- Australia, for such matters as membership and general
- enquiries. Enquiries can also be made by packet to the
- President (Col) VK2CTD, or the Secretary (Pat) VK2JPA @ VK2OP.
-
- News items may be sent to Broadcast Officer PO Box 60
- Blacktown 2148 Australia, or by packet to VK2JPA @ VK2OP.
-
- Email addresses for the Broadcast Officer are :
-
- patl@extro.ucc.su.oz.au or VK2JPA@VK2OP nsw.aus.oc
-
- The Society welcomes news items on any digital subjects from
- anywhere in the broadcast footprint. We know we reach ZL and many
- South Pacific islands. We are looking forward to news from your
- areas to let other amateurs know what you are doing in the hobby.
- Hope to hear from you.
- 73s de Pat VK2JPA Broadcast Officer
- That concludes ANARTS NEWS BULLETIN 799 06/03/94.
- INSERTED BY VK2BQS (Jim) Vice-President ANARTS.
-
- --
- Dave Horsfall (VK2KFU) VK2KFU @ VK2OP.NSW.AUS.OC PGP 2.3
- dave@esi.COM.AU ...munnari!esi.COM.AU!dave available
-
- ------------------------------
-
- Date: 7 Mar 94 21:47:00 GMT
- From: nprdc!ihnp4.ucsd.edu!usc!howland.reston.ans.net!gatech!swrinde!cs.utexas.edu!geraldo.cc.utexas.edu!astro.as.utexas.edu!oo7@network.ucsd.edu
- Subject: copying cw on typewriters
- To: info-hams@ucsd.edu
-
- MAHJMAC@DELPHI.COM asks:
-
- >>If the only goal [of CW testing sessions] is to make
- >>certain people are proficient in code, no matter what the means, then why
- >>couldn't a decoding device that takes audible morse and converts it into
- >>text be allowed. In under a week I could develop a program for the Sound
- >>Blaster or other audio cards that could do exactly that.
-
- Because when you are shipwrecked and have built your CW radio transmitter
- out of coconuts and paper clips, you won't be able to decode any messages
- received in response to your distress call. You have to know whether
- someone is saying "Ship will be there in 2 days", "pse QSY have been on
- this freq for last 10 hrs", or "599 TX qsl via buro, QRZ?"
-
- Derek "May Day" Wills (AA5BT, G3NMX)
- Department of Astronomy, University of Texas,
- Austin TX 78712. (512-471-1392)
- oo7@astro.as.utexas.edu
-
- ------------------------------
-
- Date: 6 Mar 94 23:08:35 GMT
- From: nprdc!ihnp4.ucsd.edu!munnari.oz.au!newshost.anu.edu.au!sserve!usage!metro!ipso!rwc@network.ucsd.edu
- Subject: IPS Daily Report 06 03 94
- To: info-hams@ucsd.edu
-
- IPS RADIO AND SPACE SERVICES AUSTRALIA
- Daily Solar And Geophysical Report
- Issued at 2330 UT 6 March 1994
- Summary for 6 March and Forecast up to 9 March
- IPS Warning 7 was issued on 02 March and is still current.
- -----------------------------------------------------------
-
- 1A. SOLAR SUMMARY
- Activity: low
-
- Flares: none.
-
- Observed 10.7 cm flux/Equivalent Sunspot Number : 096/043
-
- 1B. SOLAR FORECAST
- 07 March 08 March 09 March
- Activity Low Low Low
- Fadeouts None expected None expected None expected
-
- Forecast 10.7 cm flux/Equivalent Sunspot Number : 098/045
-
- 1C. SOLAR COMMENT
- None.
- -----------------------------------------------------------
-
- 2A. MAGNETIC SUMMARY
- Geomagnetic field at Learmonth : quiet to unsettled
-
- Estimated Indices : A K Observed A Index 5 March
- Learmonth 08 2222 1233
- Fredericksburg 12 06
- Planetary 10 05
-
-
- 2B. MAGNETIC FORECAST
- DATE Ap CONDITIONS
- 07 Mar 20 Unsettled to active.
- 08 Mar 20 Unsettled to active.
- 09 Mar 20 Unsettled to active.
-
- 2C. MAGNETIC COMMENT
- It appears that the expected coronal hole disturbance is
- not going to eventuate, or if it does it will be significantly
- milder than originally expected.
-
- 3A. GLOBAL HF PROPAGATION SUMMARY
- LATITUDE BAND
- DATE LOW MIDDLE HIGH
- 06 Mar normal normal normal
- PCA Event : None.
- 3B. GLOBAL HF PROPAGATION FORECAST
- LATITUDE BAND
- DATE LOW MIDDLE HIGH
- 07 Mar normal fair poor
- 08 Mar normal fair poor
- 09 Mar normal fair poor
- 3C. GLOBAL HF PROPAGATION COMMENT
- Degraded HF comms did not eventuate.
-
- -----------------------------------------------------------
-
- 4A. AUSTRALIAN REGION IONOSPHERIC SUMMARY
- MUFs at Sydney were 10 to 20% above predicted monthly values
-
- T index: 89
-
- 4B. AUSTRALIAN REGION IONOSPHERIC FORECAST
- DATE T-index MUFs
- 07 Mar 70 10 to 20% above predicted monthly values.
- 08 Mar 60 About 15% above predicted monthly values.
- 09 Mar 60 About 15% above predicted monthly values.
-
- Predicted Monthly T Index for March is 40.
-
- 4C. AUSTRALIAN REGION COMMENT
- It appears that the expected HF degradations are not going to
- eventuate.
- --
- IPS Regional Warning Centre, Sydney |IPS Radio and Space Services
- email: rwc@ips.oz.au |PO Box 5606
- tel: +61 2 4148329 |West Chatswood NSW 2057
- fax: +61 2 4148331 |AUSTRALIA
-
- ------------------------------
-
- Date: 7 Mar 1994 12:47:35 -0800
- From: usc!math.ohio-state.edu!howland.reston.ans.net!europa.eng.gtefsd.com!news.umbc.edu!eff!news.kei.com!yeshua.marcam.com!insosf1.infonet.net!usenet.ee.pdx.edu!news.reed.edu@ihnp4.ucsd.edu
- To: info-hams@ucsd.edu
-
- References <1994Mar2.175938.12119@alw.nih.gov>, <1994Mar3.144159.3607@ke4zv.atl.ga.us>, <1994Mar3.185052.18759@oracle.us.oracle.com>com
- Subject : Re: Further criminalization of scanning
-
- Douglas Marsh (dmarsh@erpyr.us.oracle.com) wrote:
- : In article <1994Mar3.144159.3607@ke4zv.atl.ga.us> gary@ke4zv.atl.ga.us (Gary Coffman) writes:
-
- : -- Other Quote Deleted --
-
- : >
- : >I agree, both with the idea that government is too quick to say "there
- : >ought to be a law" and that scanner hobbiests are at heart voyeurs. That's
- : >where the basic difficulty arises. Laws against Peeping Toms have existed
- : >for centuries. Congress is trying to extend that principle into the wireless
- : >age, but they're making the same mistake here as they are with the problem
- : >of violence in society. Banning scanners will be no more effective than
- : >banning guns, and has the undesirable side effect of causing unnecessary
- : >harm to legitimate users of these tools. The real problem in both cases
- : >is sick and twisted individuals with no sense of morals or ethics, not
- : >the hardware that enables them to pursue their voyeurism or violence.
- : >
- : >Gary
- : >--
- : >Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary
- : >Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary
- : >534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary
- : >Lawrenceville, GA 30244 | |
-
- : How many people were killed by scanner last year?
- : Doug :~}
-
- Private citizens stopped appoximately 1,000,000 crimes last year with
- handguns. (Prof. Gary Kleck)
-
- If only ONE life is saved, mustn't we maintain the right to own handguns?
- ^^^
-
- How many crimes were stopped/lives were saved with a scanner radio?
- (Better sharpen up the antennas on those "Assault Radios")
-
- 73's
- Gene
- KB7WIP
-
- ------------------------------
-
- Date: Mon, 7 Mar 1994 18:46:44 GMT
- From: ihnp4.ucsd.edu!swrinde!gatech!wa4mei!ke4zv!gary@network.ucsd.edu
- To: info-hams@ucsd.edu
-
- References <1994Mar3.153014.6322@arrl.org>, <1994Mar4.132650.9466@ke4zv.atl.ga.us>, <1994Mar6.173414.5886@arrl.org>
- Reply-To : gary@ke4zv.UUCP (Gary Coffman)
- Subject : Re: Medium range point-to-point digital links
-
- In article <1994Mar6.173414.5886@arrl.org> zlau@arrl.org (Zack Lau (KH6CP)) writes:
- >Gary Coffman (gary@ke4zv.atl.ga.us) wrote:
- >: In article <1994Mar3.153014.6322@arrl.org> zlau@arrl.org (Zack Lau (KH6CP)) writes:
- >: >BTW--how else does one improve a point to point link,
- >: >besides using bigger antennas and more power?
- >
- >: Ah, the DXer mentality at work. That's what those guys
- >: thought too. The only problem was, that wasn't why the
- >: link was flakey. The real problem was that they had
- >: established the world's worst exposed terminal in their
- >: single frequency network, and the link was being killed
- >: by all the DXer's with 160 watt amps and beams trying to
- >: make it to their hubs and capturing the link node's receiver.
- >: It would be held off for minutes at a time by the continous
- >: collisions.
- >
- >Actually, if you are forced to do it all on a single
- >frequency, bigger antennas and more power *is*
- >just about the only solution (to improve the link).
- >The more directive antennas would reduce chance of
- >collisions, while more power would reduce the effect
- >of a collision. Admittedly, an *ugly* situation. But,
- >politics makes it difficult to find other frequencies
- >that are those compatible with radios already in use.
-
- No, the better solution is to convince people to use
- *lower* power, and *lower* sites to reduce the exposed
- terminal problem. 40 db over S9 signals are not required,
- S2 is fine. The best solution is to use a separate non-
- contending link frequency, of course.
-
- >Yes, I know you could modify all the TNCs for some sort
- >of optimized slotted Aloha protocol, but I doubt this
- >is really practical.
-
- Right, it isn't practical, and all it takes is one joker
- who doesn't want to play to screw it up for everybody.
-
- >Getting links on clear frequencies is where microwaves
- >show their superiority. Not only is it more difficult
- >to fill the wider bands with wall to wall signals, but
- >highly directive antennas make frequency reuse more of a
- >possibility. All that money spent on VHF bricks
- >might be put to better use on microwave transverters.
-
- The price of a VHF brick might make a down payment on
- a stable microwave transverter, but you still are faced
- with the LOS problems. Cheap, narrow, stable, pick one.
- As far as I know, the cheapest suitable microwave
- *appliance* is the SSB Electronics system. It costs
- about what a VHF kilowatt does. Gunnplexers are neither
- narrow nor stable. (not to say they won't *work* for
- some unimpeded paths, but you can't co-locate a lot of
- them in one of our bands).
-
- >I'm pretty sure an analysis of the phone calls I've
- >recorded would show that its not just DXers who run
- >beams and amplifiers into their local BBS. I usually
- >end up spending an extra few minutes explaining that
- >while a beam results in stronger signals, this advantage
- >is often eliminated by the extra collisions that result.
-
- Yeah, there are others besides DXers who think power is
- the answer to every problem. And it's true that too little
- power, or too low an antenna can create hidden terminal
- problems as well. The overall MAN system has to *balance*
- to work well.
-
- >I've found that an open wire fed *HF* dipole, even
- >though it is cross polarized, works a lot better than
- >an indoor yagi for packet work, because it hears more
- >stations than the yagi.
-
- A nice outdoor vertical that hears nearly as well as
- your BBS or node is even better. Especially when coupled
- with the minimum necessary transmit power. (Phil Karn's
- pseudo-cellular approach would be best *if* the average
- ham density was high enough. Unfortunately, it's not.)
-
- Gary
- --
- Gary Coffman KE4ZV | You make it, | gatech!wa4mei!ke4zv!gary
- Destructive Testing Systems | we break it. | uunet!rsiatl!ke4zv!gary
- 534 Shannon Way | Guaranteed! | emory!kd4nc!ke4zv!gary
- Lawrenceville, GA 30244 | |
-
- ------------------------------
-
- Date: 7 Mar 94 04:16:42 GMT
- From: nprdc!ihnp4.ucsd.edu!munnari.oz.au!newshost.anu.edu.au!sserve!usage!metro!news.ci.com.au!eram!dave@network.ucsd.edu
- To: info-hams@ucsd.edu
-
- References <gradyCLxxqM.IID@netcom.com>, <5220@eram.esi.com.au>, <alh-050394143621@twilight1h160.its.utas.edu.au>
- Subject : Re: personal communication Australia <-> USA
-
- In article <alh-050394143621@twilight1h160.its.utas.edu.au>,
- alh@postoffice.utas.edu.au (Alan Hughes) writes:
-
- | But you dont *have* to leave the header there, it can be deleted and then
- | added back again later.
-
- True. I guess you could always leave the file un-armoured, and 7PLUS it
- fot transport; all of which makes the anti-encryption laws silly, since
- they're so easily circumvented. Not that I've ever done it, of course :-)
-
- --
- Dave Horsfall (VK2KFU) VK2KFU @ VK2OP.NSW.AUS.OC PGP 2.3
- dave@esi.COM.AU ...munnari!esi.COM.AU!dave available
-
- ------------------------------
-
- Date: 7 Mar 1994 16:23:04 -0500
- From: yale.edu!noc.near.net!news.delphi.com!news.delphi.com!not-for-mail@yale.arpa
- To: info-hams@ucsd.edu
-
- References <1994Feb17.144029.3459@ke4zv.atl.ga.us>, <rohvm1.mah48d-280294100619@136.141.220.39>, <2MAR199408091550@nssdca.gsfc.nasa.gov>
- Subject : Re: Keyboards at testing sessions
-
- >Just couldn't resist adding to his thread. Copying by typewriter has been
- >around for as long as their have been typewriters. Even the FCC when it
- >gave the test would let you bring a typewriter. The computer is just the
- >late 20th century typewriter. The object really is to demonstrate the
- >ability to receive code at the required level. The mechanism by which you
- >(as distinct from some computer program) write down the code is immaterial
- >and not germane to the testing of code proficiency. Not even the FCC is
- >requiring a handwriting proficiency test at a particular speed.
-
- >Erich
- >N3OXM
-
- As I was learning the code, I developed an application that would sound random
- letters, numbers, or pro-signs, and I would then press the proper key on the
- keyboard. As a high speed touch typist (> 120 wpm) I found that after a
- while, my fingers were conditioned to pressing a certain key in response to
- a certain audible pattern. When I then began attempting to write down
- what I heard, instead of hitting a key, I discovered that I was not nearly
- as proficient as I was on the keyboard.
-
- But, you bring up an even different point. If the only goal is to make
- certain people are proficient in code, no matter what the means, then why
- couldn't a decoding device that takes audible morse and converts it into
- text be allowed. In under a week I could develop a program for the Sound
- Blaster or other audio cards that could do exactly that.
-
- It would be no different than a person who can only decode morse if they have
- a typewriter or other keyboard device available. It seems to me that in this
- day and age, it is so easy to develop inexpensive devices that could decode
- morse, that the only reason to keep the test is to be certain people are
- proficient in reading and writing without devices to assist them.
-
- ------------------------------
-
- End of Info-Hams Digest V94 #260
- ******************************
-