Now suddenly an IARU band PLAN has become an FCC requirement?

    Did I miss a ruling somewhere?  When do the new FCC regulations take effect?  I can't believe I mussed the (usually) lengthy discussion and comment period.  Guess the ARRL snuck one in under our noses?  Or has the IARU taken over regulatory duties from the FCC?  (After all, "outsourcing" is very popular these days.)

HA6SST on December 24, 2007       Mail this to a friend!
One thing which may help, wire a 500 ohm resistor across each supply. I found that this improved regulation when I tried this using PC Supplies.

HA6SST
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    Almost ALL "PC" switching supplies REQUIRE a minimum load to operate at all, not just for "better regulation."  Without a load, most will simply shut down.
    But each case is different.  And some can be "floated," while other supplies have the negative sude connected to the case in multiple places through mounting  hardware, making their use in series impossible without considerable re-work.

Agreed; ask Kenwood.  There may be a reason for some capability in JA-land or other parts of the world.  Interestingly enough, there's a receive mod for their TS-790A (UHF/VHF multimode) that expands receive slightly (don't know if there's a corresponding xmit mod, and don't care...) but the mod lets the receiver go down to 136 MHz (for WxSAT reception) but also implements receive on 340-377 MHz.  Nothing of much interest there, unless they have accessories that aren't available in the U.S.
    Since it uses the 70 cm antenna input, it's not very useful, as few antennas are going to be very useful from 340-450 MHz.

QUOTE: K3AN on December 18, 2007
   "I would be very surprised to see Kenwood come out with a new HF rig. Not to worry, though. We still have four HF radio manufacturers. And two of them are American."
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    Which is even more unfortunate, because in the past the Kenwood transceivers have had (arguably) the best sounding radios on the air.  (Such as the TS940, TS-850, TS-850.)  Not sure what route "Yaesurola" will take, either.

Aaron Brothers, if you have a store near you.  Best bet is to photocopy the original, cut it apart as directed, and put the larger original part away in your fireproof box, safe deposit box, buried in the backyard, or somewhere else safe.  Then laminate the original wallet size and put it in your wallet.  (Even if not absolutely required by law.)  Laminate the copy of the larger part, and mount in the frame of your choice.
    unless placed in DIRECT sunlight, a framed copy will not fade in ten years and lamination will preserve it from air pollutants.  Many office supply storee (as well as the big Staples, OfficeMax and Office Depot) will laminate a full page for around a dollar.

    The current licenses are printed on a laser printer and no special "archival" paper is used, so they are just as susceptible to print "migration" or transfer to other substances (especially vinyl plastic) as any regular laser print or photocopy.  Lamination prevents the print from being transferred, and is recommended by the FCC.  It will not affect the validity or legality of the license.  And it's a good idea to always carry a copy in your wallet; if you visit a club station and want to operate, the first thing most will ask is to see a copy of your license to verify it's valid.  With visitors at our club, it's "no license, no operating."

A major consideration isn't just price, but EFFICIENCY.  For the same DC power input, the UHF (higher frequency) circuits are not as efficient.  many of the mobile dual band radios use hybrid modules in the output circuit, (different modules for the different bands) and the modules do not operate at the same efficiency.  Even with discrete devices in the output stage, for a given DC power input, the higher frequency circuits will not have the same power output, but will be lower.

You probably should ask Kenwood first; or get the Service manuals and compare part numbers.
    Kenwood Tech Service is usually very good (24-49 hours) at replying to e-mails, but hurry before they take time off before the holidays.

    you can get some of the manuals here:

http://www.radioamateur.eu/KENWOOD.html


    Good luck.

I'm with CJS.  IF you actually know the material (rather than just memorizing answers) it won't matter which "study guide" you use.  Even if a technical question is changed with (e.g.) a value of 800 Ohms instead of 1200 Ohms, you should be able to figure it out, if you understand the concepts.

    The place to study NEW material (and take CURRENT on-line tests) is in the area of the rulse and regulations, which have dramatically changed in the last year (give or take a few days.)  There were changes that went into effect last December, and again, BIG changes that went into effect this past February.
    those changes won't be covered by older study guides.

Good luck.

The TS-570D(G) was actually discontinued several months before the TS-570S.  It WAS pretty silly to have two models so similar in a tight market, and apparently, the TS-570S was selling better than the HF only model, particularly when competing models from YaeCom often had 6 Meters already included as a standard feature.

Yes, as of about August; supplies are limited to stock on hand.

    Supposedly, Kenwood was retooling to comply with European Environmental Regulations (including "getting the lead out") and the '570 series was old enough not to warrant retooling.  Even their accessory line is being narrowed; the optional filters that fit the '570, 450, and a few other radios have also been discontinued.  For the present, their HF line is limited to the TS-480 series, and the TS2000.

OOPS!  In the above, make that 500 Watts DC inoput PER TUBE, not 1000 Watts.  1000 Watts input would be for TWO tubes, (although some people push the tubes a bit past that value.)
    600 Watts output for two tubes, whether in parallel or push-pull, is not an unreasonable value for linear operation.

Last things first:

    A capacitor "across" the SCR probably won't help false triggering.  Depending upon the actual circuit used by Astron to trigger the over-voltage condition, a bypass capacitor placed between the SCR gate and ground may help, but might also disrupt operation by increasing the time required to trigger; if the surge or stray RF is getting into a different part of the circuit, that might not help at all.  (A value of about 100 pf might not do any harm, but might not help.)
    You might have an intermittent or loose connection in your antenna or antenna system that may change the RF radiation pattern and cause occasional RF in the shack.  Or, it was just a fluke.  If the problem doesn't return, just chalk it up the the "ghost in the machine."

Your spray treatment may not have been as "harmless" as you thought.  But to apply the spray, you probably had to "open up" the case of the radio.  Recheck for loose connectors

Good luck.

As Steve said, there should be no difference in output power for parallel, or push-pull arrangements with the same power input for the same number of tubes; as long as  the output circuitry does not introduce significant loss, which can occur in either parallel or push-pull arrangements.  So (staying within the manufacturer's ratings) if each tube can take 1000 Watts DC input, you can expect 300 watts (+/-) for each tube, with 60% efficiency, whether the tubes are connected in parallel or push-pull.  Claims to the contrary, are pretty much "snake oil."  (Of course, inefficient, high loss output circuitry CAN be designed for both parallel and push-pull configurations.)  Push-pull designs CAN be more desirable at higher frequencies, since parallel configurations can lead to (additive) input and output capacitances that are almost impossible to accomodate.

The 4CX250 series are rated for 2000 Volts @ 250 mA power input, (500 Watts) EACH, so with 1000 Watts DC power input to two tubes, it's hardly unreasonable to expect 600 Watts PEP output in Class AB2.  (Class C would probably yield 700-750 Watts)
    60% efficiency is hardly an unreasonable value for a linear amp with the 4CX250 series of tubes.