Re: [AMRadio] FS: 4CX250B price lowered
New Price $25.00 Shipped ConUS Untested. - Original Message - From: Rev. Robert P. Chrysafis [EMAIL PROTECTED] To: Discussion of AM Radio in the Amateur Service amradio@mailman.qth.net Sent: Friday, December 29, 2006 5:23 PM Subject: [AMRadio] FS: 4CX250B Came in with a lot of stuff from a local AM Station. Unknown condition. pic's available. $50.00 Shipped ConUS Thank You, Rev. Robert P. Chrysafis Universal Life Ministries (ULC) http://www.ulc.org Moderator HunterdonFree http://groups.yahoo.com/groups/hunterdonfree/ __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Toobs for Food
When David/WD5BZO and myself pulled up to Ken's/KA5RHK QTH yesterday morning, this is what we saw. Poor man spent all his money on tubes and had none left for food ;) http://w5ami.net/02180001.JPG Needless to say, we took him to an all you can eat cafe right away and left with a hoard of fine tubes... -- Suburbia is where the developer bulldozes out the trees, then names the streets after them. - Bill Vaughan __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Toobs for Food
What a sad 'sign of the times'. Poor man! ;) Mod-U-Lator, Mike(y) W3SLK - Original Message - From: A.R.S. - W5AMI [EMAIL PROTECTED] To: Discussion of AM Radio in the Amateur Service amradio@mailman.qth.net Sent: Saturday, December 30, 2006 7:50 AM Subject: [AMRadio] Toobs for Food When David/WD5BZO and myself pulled up to Ken's/KA5RHK QTH yesterday morning, this is what we saw. Poor man spent all his money on tubes and had none left for food ;) http://w5ami.net/02180001.JPG Needless to say, we took him to an all you can eat cafe right away and left with a hoard of fine tubes... __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Toobs for Food
holy chit LOL and just WHAT did y'all come away with from ken's place h uh? Ronnie On Sat, 30 Dec 2006 06:50:20 -0600, A.R.S. - W5AMI wrote When David/WD5BZO and myself pulled up to Ken's/KA5RHK QTH yesterday morning, this is what we saw. Poor man spent all his money on tubes and had none left for food ;) http://w5ami.net/02180001.JPG Needless to say, we took him to an all you can eat cafe right away and left with a hoard of fine tubes... -- Suburbia is where the developer bulldozes out the trees, then names the streets after them. - Bill Vaughan __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Caps
Thanks to everyone for your suggestions and advice on the paper versus ceramic capacitors in the SP-600 rf strip. It seems the majority advise the use of ceramic and I'll most likely go that route. I also agree with the thought that anything I put in there will be better than what I have. :-) Thanks guys! Rick __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Huge HV Mica Caps
Thanks Ed. 73, Don M. -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Ed Sieb Sent: Friday, December 29, 2006 9:58 PM To: Discussion of AM Radio in the Amateur Service Subject: RE: [AMRadio] Huge HV Mica Caps They're useful for any high power use. Guys with BC rigs can use them to replce a cap to shift frequencies to the ham bands. Ed, VA3ES --- Don Merz wrote: How much use is there for those huge mica caps made by Sangamo and Aerovox? I'm sure you're familiar with the ones I mean--they are short, white cylinders with metal end caps and have values like .002MFD at 6000V and .00015MFD at 10KV. They also have ratings like 12 Amps at 1000 KCS. Are these in any demand by rig builders? __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Toobs for Food
[EMAIL PROTECTED] writes: Poor man spent all his money on tubes and had none left for food ;) If you give a man a tube, you satisfy him for a day. It you teach a man to fish he can then trade for tubes forever. Steve WD8DAS __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Caps
Rick, I am guessing that you will be fine going ahead with ceramics since most of the SP-600 circuitry won't care. That said, there are differences between capacitor types, and within the ceramic family you have Z5U, Z5V, X7R, COG (NPO), and maybe some others. I listed those from worst to best. It is hard to find the COG (NPO) types in higher values above about .001 uf, and that is where X7R is the next best choice. So what are the differences? In short it is temperature stability, and voltage stability along with the ESR. With high impedance circuits where the bypass capacitor is .01 uf and greater, it might not make a whole lot of difference which type you choose. Then again we see a big difference if the impedance is lowered where we then need to bypass some RF current. Here is a case in point: On the Central Electronics 20A the mixer L-C tank is high Q, and is bypassed with a .005 silver mica on the B+ end. To lower the Q, a 10K resistor is across the coil (L). On later 20A's, the bypass is .005 ceramic Z5V, and for the same L-C tank Q, the parallel tank resistor had to be increased to 22K. If you take the newer version with the 22K, and replace the ceramic .005 uf with a silver mica, the Q increases to the point that instability occurs. I played a lot with that circuit on one of my QRO 20A projects, and tried every type of capacitor I had to see how they behaved where ESR was important due to the high Q of the tank circuit. Interestingly polypropylene had the lowest ESR, and therefore the stage had the highest gain. The difference was easily 6 db between the ceramic and the poly with the mica in-between. Mouser and others carry polypropylene and they are quite inexpensive. I also had RF floating on the unshielded B+ wire to the VFO, and a polypropylene capacitor knocked that down better than any other type I had. It is interesting to bridge existing bypass capacitors to see the effect on stage gain, or circuit Q. Sometimes there is gain stage regeneration from another stage where the B+ is not well filtered. This might be normal and then somebody arbitrarily starts changing the bypass capacitors. The circuit behavior might change, and maybe for the worse. Be careful! Back to the SP-600, you should expect to need a re-alignment after re-capping, and you might re-cap one stage at a time to see if anything bad happened. I got my SP-600 from Ozona Bob, W5PYT. He re-capped this one with Sprague Orange-drops all except two above the RF Turret. Those failed later, and I realized why he skipped them over. Quite a job to get at those dudes. There are several types of Orange Drops, and I believe that some are polypropylene. Regards, Jim JKO - Original Message From: Rick Brashear [EMAIL PROTECTED] To: AMRadio@mailman.qth.net Sent: Saturday, December 30, 2006 9:57:24 AM Subject: [AMRadio] Caps Thanks to everyone for your suggestions and advice on the paper versus ceramic capacitors in the SP-600 rf strip. It seems the majority advise the use of ceramic and I'll most likely go that route. I also agree with the thought that anything I put in there will be better than what I have. :-) Thanks guys! Rick __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Toobs for Food
On Sat, 30 Dec 2006, A.R.S. - W5AMI wrote: http://w5ami.net/02180001.JPG Needless to say, we took him to an all you can eat cafe right away and left with a hoard of fine tubes... If I offered a Cheeseburger with grilled onions and pickles, d'ya think he'd throw in a socket with that 813??? Just Curious Cheers John KB6SCO DM09fg Gathering the Parts to restore and modify for Ham Use, my RCA BTA-1MX __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Thank You and Toroidal transformers
- Original Message - From: Brett gazdzinski [EMAIL PROTECTED] The peak voltages are an issue, but more of a problem is the duty cycle. Running 300 watts carrier with 1200 watts pep has a much higher duty cycle then 2000 watts pep in ssb service. I think even 100 watts of AM has more of a duty cycle then 2000 watts pep ssb. That's exactly why p.e.p. is a bogus measurement for output power. It is useful for determining arc-over, voltage breakdown and flat-topping points, but of limited relevance to the loudness or strength of a signal. Don k4kyv ___ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Heavy Metal Night
- Original Message - From: Ed Sieb [EMAIL PROTECTED] The only other call I ever used on HF was VE2BAQ, my original call (which I still hold). Yet it is possble, I've been licensed for 38 years or so. For the last 16 years, my HF call has been VA3ES. So, in Canada they still let you hold two station licence callsigns. The FCC stopped doing that here sometime in the late 70's. I used to hold a W1 prefix 2-letter call as well as my present one, but I had to choose between the two when renewal time came. I decided to hold onto my original, especially since I was moving back to 4-land (not that the number in the callsign means anything anymore). Don k4kyv ___ This message was typed using the DVORAK keyboard layout. http://www.mwbrooks.com/dvorak/ http://gigliwood.com/abcd/ __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Heavy Metal Night
Up here, we can have as many 3-letter calls as we can afford, but only one 2-letter call per district. I possess 4 callsigns, VE2BAQ, VE2SS, VE3RDZ (used only for data transmissions, APRS, PSK31, etc.) and my main call, VA3ES. My Ontario auto plates are callsign plates, but they say VE2BAQ. Sure turns heaed at hamfests in Quebec! :-) Ed, VA3ES - Don Chester wrote: So, in Canada they still let you hold two station licence callsigns. __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] PEP for AM
Original Message -
From: Gary Schafer [EMAIL PROTECTED]
-Original Message-
Subject: [AMRadio] PEP for AM
Anyway, I ran across this information, and thought I'd share it with the
group here, so that some mis-conceptions about AM PEP could be cleared
up.
(from: http://www.pc-oscilloscopes.com/articles/pc_oscilloscope_rf.html)
P E P (AM)
% Modulation = (( PEP - PC) / PC) *100%
Example:
Carrier Power PC = 100 W, PEP = 400 W.
Determine % Modulation
M% = (( 400 - 100) / 100) *100% = ((20-10) / 10) *100% = 100%
Hmmm, let's see, 400 watts -100 watts = 300 watts. Divided by 100 watts =
3.
Times 100% = 300% modulation..
I think they forgot the square root of the powers in the formula.
Looks like that may add to the misconception. But I'm not sure they left
out the square root symbol. Could that be the reason for the double
parentheses on the left? Since most word processing programs do not have
easy access to mathematical symbols, and e-mail programs may not have them
at all, a special set of symbols has evolved for mathematical expressions.
I am not totally familiar with them, and I sometimes get totally lost when
trying to interpret mathematical expressions posted over the internet.
Isn't this what the formula is supposed to look like? (the problem is that
it may not display correctly if your e-mail reader does not support
Unicode).
______
% Modulation = ( √PEP - √PC ) / (√PC) *100%
Evidently they think that so few people would have a use for mathematical
formulae that maths symbols are not included in the default character set.
Just like the ricebox manufacturers who no longer include monitor scopes in
their appliance product line.
Don k4kyv
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Re: [AMRadio] Capacitors
What type of capacitors I should use to replace the paper Astron and West-Cap capacitors in the rf strip on the sp-600? I have a good stock of new Sprague Orange Drops or I can use ceramic disk. I don't want to have to do this again. Of course, at my age, it's doubtful that will happen! I tend to use orange drops to replace old wax tubular paper caps, and silver micas to replace mica caps. Disc ceramics have always worked for me to replace paper caps, but I prefer orange drops. I use disc ceramics to replace original disc ceramics, but never to permanently replace micas. From my experience, disc ceramics are the most failure-prone of all. The little red micas in older Collins gear tend to go leaky over time. I couldn't count the number of these I have replaced in my two 75A-4's and ones I have repaired for other people. One problem I have run into is that many of the standard values of micas and silver micas are getting hard to find. Like everything else offered on the commercial market, the variety of choice is steadily dwindling. For example, a couple of years ago I needed a 120 pf mica, or some specific value near that (I may not have remembered these figures correctly - and my computer is not out in the shack, but you should get the idea). I could find a 100 pf and a 110pf, or a 140 pf, but the exact value was no longer listed in any of the catalogues, and the local electronics store said they couldn't order that value for me. Someone sent me a couple of the values I needed, that they had on hand. They said they had got them from Mouser Electronics. When repairing a piece of antique gear that I want to look authentic and original, I gut the old wax paper caps, and refill them with orange drops, and re-pour melted wax to seal the modern component inside. I usually keep the original wire leads whenever possible, since modern caps tend to have smaller gauge wire leads than the older caps. I never throw away old wax caps, but keep them on hand in a special box just for that purpose in case I need them. I have done the same with large rectangular paper and electrolytics. But for something like the 75A-4, I just drop in new components to replace failed ones. Don k4kyv __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] PEP for AM
P E P (AM) % Modulation = (( PEP - PC) / PC) *100% Example: Carrier Power PC = 100 W, PEP = 400 W. Determine % Modulation M% = (( 400 - 100) / 100) *100% = ((20-10) / 10) *100% = 100% Hmmm, let's see, 400 watts -100 watts = 300 watts. Divided by 100 watts = 3. Times 100% = 300% modulation.. I think they forgot the square root of the powers in the formula. Looks like that may add to the misconception. But I'm not sure they left out the square root symbol. Could that be the reason for the double parentheses on the left? Since most word processing programs do not have easy access to mathematical symbols, and e-mail programs may not have them at all, a special set of symbols has evolved for mathematical expressions. I am not totally familiar with them, and I sometimes get totally lost when trying to interpret mathematical expressions posted over the internet. Isn't this what the formula is supposed to look like? (the problem is that it may not display correctly if your e-mail reader does not support Unicode). ______ % Modulation = ( vPEP - vPC ) / (vPC) *100% Evidently they think that so few people would have a use for mathematical formulae that maths symbols are not included in the default character set. Just like the ricebox manufacturers who no longer include monitor scopes in their appliance product line. Don k4kyv This is how it should be. % Modulation = (( vPEP - vPC) / vPC) *100% They had the parenthesis correct but didn't have the square root signs. You need the double parenthesis at the front as there are two opposite ones following. They must all balance. You perform the functions within the inner set first then do what is in the next set, then do what is outside last. I cut and pasted your square root symbols for this. Can someone tell me how to do square root symbols on a regular keyboard? 73 Gary K4FMX __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] The Sound Of Capacitors
Hi Group, The link below covers how different capacitors used as audio coupling condensers can 'colorize' or distort the audio signal. At the bottom of the page is verbage describing how the test was run. I found this very interesting. http://members.aol.com/sbench102/caps.html Regards, Jim JKO -- No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.432 / Virus Database: 268.16.0/610 - Release Date: 12/30/2006 2:59 PM __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: RE: [AMRadio] PEP for AM
Can someone tell me how to do square root symbols on a regular keyboard? Gary, You might try (X)^1/2... your raising the number to the 1/2 power, which is the same as taking the square root. ^(1/3) cube root ^ (1/4) fourth, etc.. I can't remember if the extended ascii or whatever its called now supports the 'usual' symbols.klc __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] FS: Large High Voltage Mica TX or Tesla Capacitors
For Sale: Large High Voltage Mica Transmitting Capacitors (Or Tesla Coil or paperweight or...) These are the ones in short white cylinders with metal end caps. 1 Sangamo G1 [EMAIL PROTECTED] $20 1 Sprague MX60 [EMAIL PROTECTED], 4.7A at 3MC, 3.6A at 1MC $20 1 Aerovox 1970-217 [EMAIL PROTECTED]21A at 3MC, 20A at 1MC $70 I also have 9 of the ones that are built in large square porcelain, ceramic, epoxy or micanol housings with terminals on top. Here's the list: 3 Sangamo Micanol or epoxy .006 @ 8KV, 17A at 1MC $20 each 2 Aerovox Type 86 porcelain or ceramic .001 @ 7KV, 8A at 15MC, 9A at 7.5MC, 10A at 3.75MC, 8A at 1.875MC $20 each 2 Acushnet Type 1996 porcelain or ceramic .005 @ 12.5KV, 8A at 15MC, 9A at 75.MC, 8A at 3.75MC, 7A at 1.875MC $15 each 2 Sangamo porcelain or ceramics that are unmarked. The bridge shows both of these to be close to .001MFD. These are probably 6-8KV each judging from their size. $10 each Thanks for looking. 73, Don Merz, N3RHT __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: RE: [AMRadio] PEP for AM
On Sat, 30 Dec 2006, [EMAIL PROTECTED] wrote:
Gary,
You might try (X)^1/2... your raising the number to the 1/2 power,
which is the same as taking the square root. ^(1/3) cube root ^
(1/4) fourth, etc..
The ASCII 'programming' convention is \sqrt{n}.
The labor intensive way to do an approximation of the symbol in an ASCII
monospaced font is to make the bar as an underline on the line *above* the
numbers, like:
V 2 = 1.41421...
using of course a capital 'V' in front,
but it can get messy fast, and if the recipient's mail client doesn't
handle monospacing well, it turns right into a dog's breakfast real
fast...
But, it's the Thought that Counts, at any rate!
Cheers
John
KB6SCO
DM09fg
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RE: [AMRadio] Toobs for Food
Poor man was obviously starting to fade. A hamburger is just an 807. An 813 is a bacon cheeseburger. If you made off with an 833 you should have brought him a little home for later too! :-) Best Regards, Steve White, W5SAW SW Commercial Electronics mailto:[EMAIL PROTECTED] http://w5ami.net/02180001.JPG Needless to say, we took him to an all you can eat cafe right away and left with a hoard of fine tubes... __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
[AMRadio] Collins Audio Console
A non-ham, who is a station engineer, informed me that he has a very nice Collins 212RG audio console for sale. The unit was removed from at local radio station. His phone number is 1-(850) 878-5746. His location is in northern Florida. The price that he quoted me is for serious buyers only! Thank you Dave, W3ST Publisher of the Collins Journal Secretary to the Collins Radio Association www.collinsra.com - the CRA Website Now with PayPal CRA Nets: 3.805 Mhz every Monday at 8 PM EST and 14.253 Mhz every Saturday at 12 Noon EST Collins Chatroom - Daily at 4 PM EST on 14.285 Mhz __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Heavy Metal Survey
Jack asked: wouldn't it be interesting to know how many of the folks with the capability to run illegal power, didn't or never do? I think it would be about as interesting as knowing how many people who own automobiles ever exceeded the speed limit. 73, Ken W2DTC __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Heavy Metal Survey
Jack, given the band conditions I won't venture a guess. I will say that because of both the conditions and the strong signals it managed to stop some of the SSB interference. Should many of the stations get on the air regularly, others who like to get up close with their aflack noise would rethink that strategy. I could not hear stations within 300-400 miles of me, but those beyond that were very good copy over riding the interference. At one time, I found 5 different conversations on different frequencies, so I would say the night has been a success and welcomed. Jim W5JO Don't mean to be a creep again but wouldn't it be interesting to know how many of the folks (big egos with big rigs tromping Rangers) last night, with the capability to run illegal power, didn't or never do? Anyone care to venture an opinion? js __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
Re: [AMRadio] Heavy Metal Survey
kenw2dtc wrote: Jack asked: wouldn't it be interesting to know how many of the folks with the capability to run illegal power, didn't or never do? I think it would be about as interesting as knowing how many people who own automobiles ever exceeded the speed limit. That's one way of looking at it but it seems more like burning nitro in a stock car race or shooting up before an Olympic run. Aren't hams supposed to be gentlemen? We wouldn't belch over the air, would we? js -- PHOTO OF THE WEEK: http://schmidling.com/pow.htm Astronomy, Beer, Cheese, Fiber,Gems, Sausage,Silver http://schmidling.com __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
RE: [AMRadio] Antenna/Coax
You're missimg nothing, Jack. There is no issue, really. Hooking up 50 ohm coax to a 75 ohm anteena only provides an SWR of 1.5:1, which is not excessive. That's for a flat-top dipole. (An inverted V Is indeed 50 ohms, or close to it.) Any pi-network can handle that and match it. If running a rice-box, any tuner can match it too. So Jack, there never has been a problem with 75 ohm dipoles, since the mismatch is not a big deal. Ed, VA3ES Jack Schmidling wrote: If a half wave dipole has a center feedpoint impedance of 73 ohms, why am I using 50 ohm coax. snip In the process of hunting up a source for coax I stumbled into this quandary. Every source I look at says 73 ohms for a dipole. What am I missing? __ AMRadio mailing list List Home: http://mailman.qth.net/mailman/listinfo/amradio Partner Website: http://www.amfone.net Help: http://mailman.qth.net/mmfaq.html Post: mailto:AMRadio@mailman.qth.net
