Actually, gain will be MORE dependent upon boom length (usually expressed in wavelengths or fractions of a wavelength) than element number.  Increasing element number usually affects the radiation pattern and bandwidth more than gain.  Thus, for a 12 foot boom length, a 4 el. Yagi may have the same or similar gain as a 5 element Yagi on the same boom; a 5 el. Yagi may NOT have more gain that a 4 element Yagi.  
    For typical gain values, you can find the old "NBS" designs in some of the ARRL Handbooks.  A better estimation will be achieved with EZ-NEC or similar modeling software; the more accurately you input data and dimensions, the more accurate will be the gain estimate.
    But without exact information on YOUR design, it's almost impossible to give other than "ballpark" figure estimates, and that's assuming an efficient and properly matched dirven element and feed system.

Software was originally provided with the TS-570 when it was first released.  It was (I believe) designed for Windoze95, and apparently worked with Win 98.
    At some point, (probably with the release of the "G" version) the software was dropped.

    Contact Kenwood Amateur Technical Service, and they will send a copy on request.

Was just wondering what frequencies and type of antennas are used by NASA to communicate with the new Robot that just landed on Mars ?? Wow, talking about DX...lol


Aww, geez.  Doesn't everybody have a 70 Meter dish in their backyard?

I'll vote for Texas Towers also.  TT has prices lower than local dealers (shipping included!) and the 6' lengths of tubing can be shipped by UPS.  10' or 12' lengths have to be shipped by freight; the cost of which is a fright!

If you get a copy of the RSGB VHF/UHF manual, they give instructions and diagrams to set up a CP antenna for CP rightl left, vertical, and horizontal polarization.  But it will take a couple of relays (or switches) and some phasing lines.

W0GSQ on April 10, 2008       
Yes, they fit very tight. If you tried disconnecting it from the radio by pulling on the coaxial cable you would more than likely be holding a cable that needs a new end!

    OR, picking up pieces of radio from the floor...
    It's NEVER a good prac tice to try to remove a connection by pulling on the cable, whether it's a push-on coax connector, or a simplt line cord.  if the connectors are tighter than the wire connections, you can pull the wires out of a connector (nad if it's a coax connector; worse if it's a live AC power cord.)  Just as bad, the connectors and cable may NOT release, and you can pull a piece of equipment on to the floor, with equally as disastrous results.

It's also true that many (many, meaning more than a handful, but not meaning most, and certainly not all) Amateurs do not have the tenacity, interest, ability, expertise, or patience to "bother" with such a modification.  they would most likely want to "put it on the air," as-is.

 WA2JHS on April 9, 2008       Mail this to a friend!
....But I wonder why they put a bandswitch on them with 40,20,15 and 10 meters??? guaranteed to use sweep tubes, but if its cheap enough, why not use it to get more than 100 watts??? interesting.....
Bill
 

=====================

    Why not?    Let us count the ways:

1.  If it's cheap, the sweep tubes are probably bad; and replacements will cost more than the amp's original price.
2.  It will be dirty and splatter, because amps targeted at the "CB" operators are only designed for max power, not a clean signal.
3.  the "band switch" is just a poor excuse to try to claim it's not merely a "CB" amp.
4.  There's precious little, if any filtering so harmonic suppression is virtual non-existent.
5.  Making it "legal" and in compliance with even the less stringent Amateur Technic Standards for signal quality and harmoniuc suppression will be more costly than it's worth in terms of time and components; is it REALLY worth a letter from the FCC about a less than Amateur quality signal, not to mention the people you will alienate on the bands by having a dirty signal with splatter and othe r interference?
6.. Are you technically qualified and experienced enough to add the circuitry necessary to ensure the amp DOES comply with the Technical standards set out in §Part 97?
7.  How much power will the amp REALLY produce, realistically, not relying on super-inflated "CB" style claims?

While it may be against code to replace wired detectors, it is probably unwise to rely solely on AC powered ones.  In the event of a power failure (earthquake, fire in a different part of an apartment building, etc.) you are without protection.  At least ADD some battery powered units.  Many AC powered units (particularly those that are OEM in a new house) don't have a battery back-up, or the battery never gets replaced.  And remember to test the detectors every month.

According to the specs for the SM-230, it can handle 2 kW between 1.8 and 80 MHz... for 5 Minutes max.  It doesn't specify what mode, if that's CW, RTTY, AM, or whatever.

    I'd hesitate to keep it in-line with a legal limit amp without providing additional attenuation.  It was originally designed to bre used with the TS-850 and TS-950, which have 100 and 150 Watt outpus, respectively.

    It's also rated only 100 Watts PEP from 30-150 MHz.  (Yes there is some discrepancy, between the 80 MHz max and the 30-150 MHz rating.)

A power supply is indeed a good learning experience, and perhaps one of the simplest circuits an Amateur can attempt (except, perhaps a simple CPO.)

    But there are power supplies, and there are POWER SUPPLIES.
    A unit capable of 20-30 Amperes in not the same as building a 2 Amp supply for an H-T.
    You DO have to take careful consideration of thermal (heat sink) requirements for the rectifiers as well as the pass transistors, and properly allow for high current wiring inside the supply.

    From that standpoint, it might be less "expensive" to buy a supply than build one, particularly if all parts have to be purchased new.
    While I am all for "homebrew" when possible, there does have to be a balance between checkbook, experience level and other considerations of buy vs. build.  Often, it's easier (despite the learning experience) to buy a simple device as a power supply, and apply the effort to other accessory projects or antenna building.

    BTW, the ASTRON nomenclature is hardly "deceitful."  ASTRON clearly states up front the continuous current rating of their supplies, and it's clear from any of their documentation that an RS-35 supply can provide a maximum or peak of 35 Amperes, but the continuous rating IS 25 Amperes.
    The same "rating system" is common in the industry; Icom and Kenwood both rate their supplies similarly.
    The real problem would be trying to use a supply rated "20 or 25 Amps peak" which would only allow 15-17 Amperes continuous, with a modern transceiver that requires 20-22 Amperes, particularly in a high duty cycle mode, such as AFSK or RTTY.
   

There are quite a few sites that have the wiring diagrams for the various Bell System (Western Electric) telephones, including the "pulse dial" types.  Does anyone know of a similar site or sites that give the wiring diagrams for "GTE" telephones?

 by K9KJM on February 28, 2008       Mail this to a friend!
The Best coax for your application is Times LMR-400.
At only .69 cents a foot from Texas Towers, WHY take a chance on some "clone" or "just as good as" product?
http://texastowers.com/lmr.htm

Note that many early versions of Belden 9913 had MAJOR problems! Therefore is best to avoid.

Belden RG-213, While great coax for HF, Is NOT a good choice for VHF or UHF. Much too lossy.

IF money is a problem, You could get by with some surplus RG-11 from a friendly cable TV installer.....

RG-11 is 75 ohm, Just like your RG 59, But much lower loss, And also about free if you ask for a "spool end" from a local cable guy.........
(Common PL-259 connectors will work with it)

The "loss charts" that some people rely on are only a basic calculation plot, Out in the real world when you add connectors and some age, The loss is always MUCH MORE than those neat charts show. And once that signal is lost in the coax, It is gone forever.
Poor coax (And antennas) are why some people say "there just is not much on VHF or UHF"...........

They just have NO IDEA what they are missing by using crummy feedline.
 
-------------------------------------

    I'll agree LMR-400 (or similar) is the best choice for two meters.  (There ARE good to excellent cables that are similar to LMR-400, including a Belden foam-insulated version of 9913.)

    If you have to buy cable, get GOOD cable, and you won't regret it.  And good, low loss cable will be usable if you ever want to upgrade to a better antenna system, or want to try your hand at "weak signal" work.  (Antenna polarity would still be a concern, however.)


    While the "loss charts," and such ARE only guidelines, and should not be used for real world values , they ARE still valid for comparison.  Even given loss due to weather, connectors, etc, all things being equal, a cable with lower loss in the tables will have lower loss when exposed to weather for ten years, and will have lower loss if the number and type of coax connections are the same.  the loss may be greater than expected or predicted from the "tables," but the comparison will still be valid.

Isn't 1200 Volts just a BIT high for the plate voltage of sweep tubes?  If the tubes were pushed that much, they probably didn't, don't, and won't have a very long life.  Replacements may co$t more than tha amp is worth...

Direct Quote:  (As revised 1 October, 2007.)

"...Sec. 97.313  Transmitter power standards.

    (a) An amateur station must use the minimum transmitter power
necessary to carry out the desired communications.
    (b) No station may transmit with a transmitter power exceeding 1.5
kW PEP.
    (c) No station may transmit with a transmitter power exceeding 200 W
PEP:
    (1) On the 10.10-10.15 MHz segment;
    (2) When the control operator is a Novice Class operator or a
Technician Class operator who has received credit for proficiency in
telegraphy in accordance with the international requirements;"


    So what the rule ACTUALLY says, is that Techs who have code proficiency are limited to 200 Watts, but "Plain ol' Techs" have full legal limit???

    Then again, since there's no such thing as a Tech who has "received code proficiency in accordance with International 'Requirements,'" because the requirements no longer exist,  the portion of that rule is moot and can be argued that it no longer applies to Techs.

    Also remember the FCC reserves the right to issue "errata" to the Rules and Regs when they find unintentional errors in wording of rules.