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- Date: Thu, 31 Mar 94 12:43:24 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 #354
- To: Info-Hams
-
-
- Info-Hams Digest Thu, 31 Mar 94 Volume 94 : Issue 354
-
- Today's Topics:
- But Seriously (was Re: New Award Announcement
- CALLBOOK ON INTERNET
- Hams, FCC, Delays, BS walks
- Hot Water 100
- How phasing SSB Exciters Work (Was: RF and AF speech processors)
- Kill that intermod!
- Multimode Controllers
- Rec.Radio.Amateur.Antennas activity??
- STOP SENDING HAMS ON USENET CRAP !!!
- Talking to seismic packages over a radio link
- The word HAM
- Voice mail on a repeater?
- WANTED: List of Cellular Freqs, Channels, etc.
-
- 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: Wed, 30 Mar 1994 16:18:46 GMT
- From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!pipex!sunic!psinntp!psinntp!arrl.org!ehare@network.ucsd.edu
- Subject: But Seriously (was Re: New Award Announcement
- To: info-hams@ucsd.edu
-
- Robert Carpenter (rc@cmr.ncsl.NIst.GOV) wrote:
-
- : Deignan and Hare lament the lack of "awards" available to no-code techs.
- : Where have they been?
-
- : Two that I can think of are:
-
- : 1) RCC Rag Chewers Club
-
- Well, although I applaud the encouragement of real contacts with real
- conversations, this just seems too easy on VHF simplex or through
- a repeater. Keep it around, but we need something more challenging.
-
- : 2) VUCC VHF UHF Century Club 100 grid squares on 6, or 100 on 2 ,
- : less on the higher bands. Yes it does require SOME effort, and more
- : than a handitalkie, but do we want to dumb-down even the operating awards.
-
- Actually, it requires a LOT of effort with a modest station. The analogy
- on HF is that with a 100-watt class station and a dipole, one can
- attain DXCC in a year or so of casual operating. Some have even done
- it in a single contest weekend, or come real close, at any rate. Perhaps
- a 100-watt/dipole combination is a "typical" HF modest station. On VHF,
- a 10-watt station with a ground plane might be more typical. How easy
- is it to work 100 grids on 2 meters with that combination? Those
- who want to pursue the award, including Technicians, can do so,
- but it seems that it is really tailored toward the effective weak-signal
- station. I don;t propose that we make a no-work award, just one that
- has enough meaning to make it worthwhile, yet can still be done
- by the typical VHF station/operator. Do remember that my proposing
- an idea carries no more weight than anyone else; when it comes to
- awards, I do NOT represent ARRL other than as a member.
-
- : 3) Various satellite operating awards.
-
- : So, there are a number of operating awards available to the no-code ham
- : ... and I might point out that DXCC CAN be achieved by a no-coder on six
- : meters, given another good solar cycle.
-
- And for that reason, I propose we keep it. But it is probably an order
- of magnitude harder than DXCC on 20 meters. I just wonder if we want more
- operating awards for other types of operation. All in all, it is not an easy
- task -- striking a balance between achievement and attainability.
-
- BTW -- I changed the subject to be the same as the change chosen by Greg
- Bullough, just to keep the thread intact. (I liked Greg's idea a lot,
- BTW BTW.)
-
- 73 from ARRL HQ, Ed
- --
- Ed Hare, KA1CV, ARRL Laboratory, 225 Main, Newington, CT 06111
- 203-666-1541 ehare@arrl.org
- My electronic posts and email do not necessarily represent the policy
- of the ARRL, but I can probably get in trouble for them anyway!
-
- ------------------------------
-
- Date: Wed, 30 Mar 1994 20:54:45 GMT
- From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!math.ohio-state.edu!magnus.acs.ohio-state.edu!csn!cherokee!walter!dancer.cc.bellcore.com!not-for-mail@network.ucsd.edu
- Subject: CALLBOOK ON INTERNET
- To: info-hams@ucsd.edu
-
- In article <CnErML.41F@eskimo.com>, Bill Turner <wrt@eskimo.com> wrote:
- >In article <1994Mar28.133651.340@pacs.sunbelt.net>,
- >DORR DEPEW <ddepew@CHM.TEC.SC.US> wrote:
- >>I have heard that there are several Callbook databases available
- >>through the net, but have been unable to locate any. If you have
- >>one that you like to use, please let me know by E-Mail. Thanks.
- >>N4QIX
- >
- >I know of one: telnet to callsign.cs.buffalo.edu 2000 and do the usual
- >readmes, etc. This is FCC data only, so no furriner info available. If
- >anyone knows of others, I'd like to know about 'em too.
- >Bill, W7LZP
-
- I've used the buffalo.edu callsign server to also obtain Canadian
- ham data.
-
- 73s
- Bill K2UNK
-
- ------------------------------
-
- Date: 31 Mar 94 17:20:12 GMT
- From: agate!howland.reston.ans.net!news.cac.psu.edu!news.pop.psu.edu!ctc.com!news.mic.ucla.edu!nntp.club.cc.cmu.edu!cantaloupe.srv.cs.cmu.edu!dolphin!ed@ucbvax.berkeley.edu
- Subject: Hams, FCC, Delays, BS walks
- To: info-hams@ucsd.edu
-
- I am in the same waiting game as others waiting for my 1st call sign.
-
- The FCC (GOV'T as whole) seems to cater to the big groups & big $$$.
- ( Yeah ok Ed, nothing we already dident know. )
-
- I am surprised as to how few STRONG electronic techs & engineers there
- are anymore. Yes the trade schools are turning grads out in droves, but
- I bet that my wife could do more to trouble shoot a digital dashboard
- in a GM car than could the majority of Graduated Electronic techs!
- And she has only learned from watching me.
-
- I recently looked for some Ham Radio Magazines, but only found 1 after
- a long drive to a large magazines only shop.
-
- I remember years back, you could go to just about any convience store
- or food store and get Popular Electronics, Radio Electronics, Elementary
- Electronics, CQ, 73, and on some occasions QST.
-
- Those days are gone. I counted no less than 12 different Wrestling
- mags, 6 music magazines, 5 bridal mags, 6 off road mags, 3 hot rod mags,
- 4 different bathing suit mags (sim to sports illustrated swimsuit)
-
- Not to pick on you fella, but 1 ham, who dident know how to hook up
- a commercial antenna tuner to a long wire! Perhaps this was a
- problem from how he studyed electronics or got his license.
- Who still goes out and buys something and takes it home, uses it for
- about a day to get to know it, and then takes it apart?
- At least a looksee as to how it looks inside, how the cables & connectors
- go together, what type of components are on the board.
-
- At my job, we have entry level data entry people who make higher salarys
- than the Trained & Experienced Technicians who do the final test &
- debugging of the products.
-
- It seems that Technicans & Engineers are a dying/ignored group,
- bean counters & paper pushers are the cream of the crop.
-
- I heard on the pgh repeater "09" last night the local Red Cross
- liason (sp?) conducting a net & asking for 50+ more volunteers for
- the upcoming Pittsburgh Marathon for communications.
-
- I am able bodied, have a 12 speed mountain bike, an older used but
- fully functional 2m HT, and a desire to serve the community...
- but until the N3??? comes in, I am just another spectator.
-
- Does anybody care?
-
- Are hams considered a benefit to the community or just a bunch of
- ragchewers to keep the fcc busy doing telephone interference tests.
-
- This is my own personal opinion and may not to reflect
- my employers or radio amateurs feelings as a group.
-
- Ed
-
- ------------------------------
-
- Date: 31 Mar 94 16:16:13 GMT
- From: dog.ee.lbl.gov!agate!blanket.mitre.org!linus.mitre.org!mwvm.mitre.org!M14494@ucbvax.berkeley.edu
- Subject: Hot Water 100
- To: info-hams@ucsd.edu
-
- >I bought an old heath kit HW100 for $150.00 I guess it doesn't matter
- >much now, but is this average going price or did I get ripped off.
-
- If the radio is reasonably clean, works ok, and came with the power
- supply, that's not a bad price. It's not exactly the deal of the
- century, but you didn't get ripped off, either. If you like HF operation,
- you will want to upgrade to a more capable radio soon. The good news
- is that the HW-100 has pretty much bottomed out in value, and with luck,
- you can use for a year and then sell it for most or all of what you
- paid for it.
-
- Mike, N4PDY
-
- ------------------------------
-
- Date: Wed, 30 Mar 1994 19:47:45 GMT
- From: ihnp4.ucsd.edu!swrinde!emory!wa4mei!ke4zv!gary@network.ucsd.edu
- Subject: How phasing SSB Exciters Work (Was: RF and AF speech processors)
- To: info-hams@ucsd.edu
-
- Well at worst I've stirred up an interesting discussion. :-)
-
- In article <CnG3Jt.Htw@srgenprp.sr.hp.com> alanb@sr.hp.com (Alan Bloom) writes:
-
- >The audio phase shift network is the interesting (read difficult) part
- >of the system. It must maintain a 90 degree phase difference and
- >excellent amplitude matching between the two outputs over something like
- >a 10:1 frequency range (300 Hz - 3000 Hz). It generally does that by
- >causing each of the two outputs to have a constantly-rising phase shift
- >versus frequency characteristic, like thus:
- > / /
- >Phase Shift / /
- > / /
- > 720 deg / /
- > / /
- > / /
- > 540 deg / /
- > / /
- > / /
- > 360 deg / /
- > I / /
- > / / Q
- > 180 deg / /
- > / /
- > / /
- > 0 deg ___/_/
- > | | | | |
- > 300 600 1200 2400 4800 Hz
- > Frequency
- >
-
- Now this chart illustrates the problem I've been talking about. As
- we can see, the difference in delay with frequency is quite marked.
- Sure the phase delay increases *smoothly* with frequency delta, but
- the magnitude of the error rapidly climbs with increasing frequency
- delta. This is our old friend click-boom. From 600 Hz to 2400 Hz delay
- decreases by almost 20%, or about 0.2 ms. That much delay difference
- is clearly audible.
-
- If we look at Tom Bruhns' chart for a more complex matrix network:
-
- phase filtered
- >freq phase error mag mag
- >Hz degrees degrees dB dB
- >200 -193.5 54.6 2.2 -8.4
- >400 -245.6 15.8 0.7 -.5
- >527 -267.6 2.3 .3 0
- >606 -278.8 -3.8 .2 0
- >696 -290.2 -9.2 .1 0
- >800 -301.6 -13.8 0 0
- >1056 -324.5 -19.9 0 -.1
- >1213 -335.9 -20.9 0 0
- >1600 -358.4 -17.8 .2 0
- >2111 -380.4 -6.1 .6 -.1
- >2425 -391.1 3.9 .8 -.5
- >2786 -401.7 17.2 1.1 -1.2
- >3676 -421.5 56.1 1.6 -4.1
-
-
- Now this is much better. The ends are horrible of course, but in the
- region 600-2400 Hz there is only a delay delta of 0.014 ms. That's
- hardly audible at all to someone with *good* ears. I'd note that this
- matrix phase shift network is considerably more complex than typical
- networks found in older phasing type equipment. And as Richard Karlquist
- noted, that's all for naught anyway unless the IF filtering of the
- receiver has correspondingly flat phase delay. Good RF filters can be
- as flat away from their edges as the matrix above, and RF filters work
- both ways.
-
- 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: Wed, 30 Mar 1994 18:33:18 GMT
- From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!EU.net!sunic!psinntp!psinntp!arrl.org!ehare@network.ucsd.edu
- Subject: Kill that intermod!
- To: info-hams@ucsd.edu
-
- The ARRL Laboratory wants to start testing the out-of-band intermod
- performance of VHF FM rigs and publishing the results in our
- QST Product Reviews. We are already measuring in-band third-order
- IMD, so the test methods are established. What I would like is
- some reports on specific out-of-band IMD problems that are being
- experienced in metro areas, frequencies, locations, etc. Please send
- the reports to ehare@arrl.org.
-
- Some of the "IMD" problems being reported are probably receiver
- image problems, so we are also going to measure and report the
- image rejection. If anyone has reports of image-response interference,
- I would like to know about that, too.
-
- Thanks,
- 73 from ARRL HQ, Ed
-
- --
- Ed Hare, KA1CV, ARRL Laboratory, 225 Main, Newington, CT 06111
- 203-666-1541 ehare@arrl.org
- My electronic posts and email do not necessarily represent the policy
- of the ARRL, but I can probably get in trouble for them anyway!
-
- ------------------------------
-
- Date: 31 Mar 94 18:07:10 GMT
- From: news-mail-gateway@ucsd.edu
- Subject: Multimode Controllers
- To: info-hams@ucsd.edu
-
- I'm in the market for a multimode controller. The AEA PK-900 looks the
- best, but it's too expensive for me (I'm looking to spend approx
- $300). Right now I'm leaning toward the Kantronics KAM Plus. Does
- anybody have any experience w/ the Kam Plus? Do you like it? How well
- does the Hostmaster software work for you (I'd be running the Mac
- version, but I'd be interested in feedback on any version--if the windows
- version is good, the Mac version probably is too). Of course, if anyone
- thinks I should be looking at a different unit all together, pse let me know.
-
- TNX es 73 de KB2PWM
-
- ------------------------------
-
- Date: Wed, 30 Mar 1994 22:14:46 GMT
- From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!wupost!gumby!newsxfer.itd.umich.edu!ncar!csn!col.hp.com!news.dtc.hp.com!hplextra!hpscit.sc.hp.com!icon!greg@network.ucsd.edu
- Subject: Rec.Radio.Amateur.Antennas activity??
- To: info-hams@ucsd.edu
-
- Teacherjh (teacherjh@aol.com) wrote:
- : >>> I have posted two items to a newsgroup, rec.radio.amateur.antennas,
- : >>> but have never ever seen any other activity on that newsgroup. I have
- :
- : > Perhaps if you changed it to rec.radio.amateur.antenna (singular)
- :
- : Where would posts posted to the plural go? The bit bucket?
- :
- : Jose KD1SB
- :
-
- No, actually. comp.* plurals go to the bit bucket, but rec.radio.* plurals
- get bled off to ground. An interesting reaction occurs when someone dumps
- the a full bit bucket onto the ground, where the comp.* and rec.radio.*
- plurals mix. I think they call it "packet".
-
- :-)
-
- Greg KD6KGW
-
- :-)
-
- Greg KD6KGW
-
- ------------------------------
-
- Date: Wed, 30 Mar 1994 14:44:37
- From: ihnp4.ucsd.edu!usc!yeshua.marcam.com!news.kei.com!ssd.intel.com!chnews!ornews.intel.com!ccm.hf.intel.com!brett_miller@network.ucsd.edu
- Subject: STOP SENDING HAMS ON USENET CRAP !!!
- To: info-hams@ucsd.edu
-
- In article <764973671snx@bsdihi.atr.bso.nl> dihi@bsdihi.atr.bso.nl (Dick Hissink) writes:
-
- >It happens again and again. Every couple of weeks six tremendous large
- >files with AMATEURS ON USENET. This times each part from the six even
- >three times. I think al the FCC's and PTT's like it, because it keeps
- >my modem so busy....
-
- >AMATEURS ON USENET: Those interested can download the latest updated
- >version by ftp form server....
-
- >This saves a lot of unnecessary downloadtimes, my phonebill and I must
- >say some irritation.
- >What do Y'all think of my idea??
-
- I'm fairly sure it is also posted to rec.radio.info There is no need to post
- it here - That's what rec.radio.info. is for.
-
- Brett Miller N7OLQ brett_miller@ccm.hf.intel.com
- Intel Corp.
- American Fork, UT
-
- ------------------------------
-
- Date: Wed, 30 Mar 1994 22:17:47 GMT
- From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!news.cac.psu.edu!ems.psu.edu!pangaea.ems.psu.edu!sak@network.ucsd.edu
- Subject: Talking to seismic packages over a radio link
- To: info-hams@ucsd.edu
-
- Hi all, a novice question on radios and radio-modem links.
-
- I have an experiment where a bunch of seismic packages (refteks) are
- scattered over the Antarctic ice sheet. They are all within about 40
- km of a central site. I would like to interrogate them about their
- state-of-health from this central site. I don't need a high-speed
- link (I am not downloading seismic data over the radio, just some
- relatively small strings of data).
-
- The refteks usually are interrogated by walking up to them, hooking up
- a little hand-terminal with an rs-232c connection and sending queries
- and getting back answers. This is a full-duplex connection.
-
- I would like to use VHF radios at approx 10W and a good antenna/tower
- to get the distance, and get the same functionality, but from the
- comfort and luxury of my central hut.
-
- My questions:
-
- 1. Are there radio transceivers out there that will operate in
- full-duplex. i.e. transmit *and* receive at the same time, over two
- different frequencies?
-
- 2. Are there modems out there that will work seamlessly with above
- radios?
-
- 3. Are the modems "intelligent". i.e., I want to be able to say
- "station 6, tell me foo", and only the modem at station 6 passes on
- the request to the seismic package, and replies with the response. I
- can't program the refteks to "know their name" --- the refteks are
- off-the-shelf.
-
- 4. I also need to be able to say "all stations, start recording NOW",
- without having to cycle through "station 1, start", "station 2,
- start", and on down the list. This is a timing matter. I want to
- have all the stations turn on at the same time to record an event.
-
- 5. And finally, how much approx for each radio/modem? And any
- pointers on who sells these things would be much appreciated.
-
- 6. Some people have said that I can't expect to just walk into Bob's
- Radios and walk out with a radio. That there are all sorts of FCC
- this-n-that before anybody will sell me anything. Is that the case?
- Please note that this is a *solely* Antarctic project, and will not be
- used in the US.
-
- I appreciate any and all help you can give me. I am not
- radio-literate, or modem-litereate, for that matter, so excuse the
- ignorance of my questions.
-
- Any and all help gratefully accepted.
-
- Cheers, Sridhar.
-
- --
-
- *******************************************************************
- Sridhar Anandakrishnan TEL: (814) 865-7042
- Earth System Science Center (814) 863-1700
- Penn State University FAX: (814) 865-3191
- University Park, PA 16802 email: sak@essc.psu.edu
- *******************************************************************
-
- ------------------------------
-
- Date: Wed, 30 Mar 94 17:27:01 -0500
- From: ihnp4.ucsd.edu!swrinde!cs.utexas.edu!howland.reston.ans.net!noc.near.net!news.delphi.com!usenet@network.ucsd.edu
- Subject: The word HAM
- To: info-hams@ucsd.edu
-
- We have a number of British-born hams here at Intel. They all agree that
- "ham" is an ancient English idiom for any kind of amateur in any field. That
- fits perfectly with what I was told by my Elmer in the early '50s. The
- application of "ham" to actors was for the same reason... amateur actors
- tend to overact. The origin of the pronounciation is the first syllable
- of the old-English pronounciation of amateur.
-
- 73, KG7BK, CecilMoore@Delphi.Com
-
- ------------------------------
-
- Date: 30 Mar 1994 21:21:30 GMT
- From: ihnp4.ucsd.edu!usc!nic-nac.CSU.net!charnel.net.csuchico.edu!charnel!olivea!news.bbn.com!news!levin@network.ucsd.edu
- Subject: Voice mail on a repeater?
- To: info-hams@ucsd.edu
-
- In article <bote.764956634@access1> bote@access1.digex.net (John Boteler) writes:
- jherman@uhunix3.uhcc.Hawaii.Edu (Jeffrey Herman) writes:
- >Are there any repeaters left in this country that just repeat, including
- >no musical tones or beeps when you drop your carrier? I miss the old
-
- Try the 147.180 repeater in Silver Spring, Maryland.
-
- Or 147.045 in Nashua, NH. Or 145.23 in Boston. There are lots around
- here that don't beep.
-
- In fact that is some sort of religious issue; the people on the home
- machine (147.045) are beep haters; but there's one in the next town
- (at 146.73) for those who really like it (plus it has an autopatch)
-
- /JBL
- =
- Nets: levin@bbn.com | "GO TO JAIL. Go directly to jail. Do not pass
- POTS: (617)873-3463 | Go. Do not collect $200."
- KD1ON (@KB4N.NH.USA) | -- Parker Brothers
-
- ------------------------------
-
- Date: 30 Mar 1994 22:04:14 GMT
- From: ihnp4.ucsd.edu!swrinde!cs.utexas.edu!howland.reston.ans.net!vixen.cso.uiuc.edu!newsrelay.iastate.edu!hobbes.physics.uiowa.edu!news.uiowa.edu!panda@network.ucsd.edu
- Subject: WANTED: List of Cellular Freqs, Channels, etc.
- To: info-hams@ucsd.edu
-
- Mike I will be glad to help. First, I am assuming you require the
- channelization for the US standard analog system (EAMPS). Secondly that you
- can use a spreadsheet to generate the complete list from my formula.
- EAMPS has 832 channels the reverse channel (Mobile TX) is from 824.04 to 848.
- 97 MHz and the Forward channel (Mobile RX) is 869.04 to 893.97 MHz. It should
- be obvious that this indicates a 45 MHz duplex spacing. The formulas to
- generate the list are as follows
-
- For Channels 1 to 799:
-
- Reverse Frequency = 825.00 MHz - (.03 * Chan. Number)
- Forward Frequency = 870.00 MHz - (.03 * Chan. Number)
-
- For Channels 991 to 1023
-
- Reverse Frequency = 825.00 MHz - (.03 * (1023 - Chan. Number))
- Forward Frequency = 870.00 MHz - (.03 * (1023 - Chan. Number))
-
- I know what you are thinking, He said 832 channels yet he has channel 991 to
- 1023 which are lower in frequency than chan 1 to 799. The reason is because
- the expansion of cellular has been so great that new frequencies became
- available a new channel plan was created and well you know the FCC they have
- trouble counting so we have a screwing channel to frequency assignment. As for
- the frequency assignment for each cell in your area. Well I do not have access
- to that type of information and if I did I could not give it you. You can try
- to contact the cellular carriers in your area but they probably will not givit
- to you. Good luck
- ---
- _________________________________________
- The opinions in this post are mine and my cat's, not my employer's.
- scottm@csg.mot.com (Scott F. Migaldi)
-
- ------------------------------
-
- Date: Wed, 30 Mar 1994 15:08:33 GMT
- From: ihnp4.ucsd.edu!usc!howland.reston.ans.net!pipex!sunic!psinntp!psinntp!arrl.org!zlau@network.ucsd.edu
- To: info-hams@ucsd.edu
-
- References <1994Mar25.155240.899@ke4zv.atl.ga.us>, <1994Mar26.201156.9246@arrl.org>, <1994Mar29.160241.20722@ke4zv.atl.ga.us>
- Subject : Re: RF and AF speech processors. Was: FT-990 vs TS-850
-
- Gary Coffman (gary@ke4zv.atl.ga.us) wrote:
- : In article <1994Mar26.201156.9246@arrl.org> zlau@arrl.org (Zack Lau (KH6CP)) writes:
-
- : >SSB crystal filters are designed for steep skirts for good
- : >shape factors. This means that without any equalizing networks
- : >(which normally double the complexity and send the cost through
- : >the roof), the phase response at the passband edges are *terrible*
- : >The fact that the center frequency of the crystal filter is much
- : >higher just means that the Q of the parts has to be that much
- : >better. The mathematics of the phase and amplitude response
- : >tradeoffs are unchanged-- the tradeoffs are identical for a
- : >3 kHz audio filter and a 3 kHz SSB filter (assuming ideal
- : >parts--with real parts its easier at audio...)
-
- : Apples and oranges. The phasing SSB exciter is using an audio
- : *phase shift network*, the filter exciter is using a RF filter.
- : Now the AF phasing network may be considered a sort of filter,
- : but that's not it's designed purpose, and for sure it's not a
- : 3 kHz bandpass response. Instead it has to maintain a constant
- : 90 degree phase shift across multiple octaves. That's tougher.
-
- Actually, what I was writing about was Gary's misconception that
- phase distortion is somehow much easier to deal with if you
- move the center frequency higher. Its actually tougher--just try
- and build a crystal frequency with good phase characteristics
- and a good shape factor. (Or, try and buy one...) Of course, it
- is true that you need an audio filter for a phasing exciter, as
- there are limits to how broad you can make the phase shift network.
- Fortunately, there is no requirement to transmit 60 Hz hum with
- perfect fidelity.
-
- I would agree that it isn't necessary for a phasing rig to have low
- phase and amplitude distortion--I'm sure that someone could work
- *really* hard and come up with one that sounded awful and still
- managed to reject the opposite sideband.
- The dark side of DSP? :-)
- But, in practice, the easiest way to make one to work well is
- to just go ahead and design for low distortion.
-
- FWIW, one of the fanatical AM types showed off his phasing
- receiver at Deerfield NH a few years ago... Guess he didn't
- notice the distortion Gary is worried about. Come to think
- of it, I don't recall hearing complaints about the Sony
- 2010's audio quality, which also uses audio phase shift
- networks. (go through the archives of the shortwave newsgroup?)
-
- --
- Zack Lau KH6CP/1 2 way QRP WAS
- 8 States on 10 GHz
- Internet: zlau@arrl.org 10 grids on 2304 MHz
-
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- End of Info-Hams Digest V94 #354
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