[MRCA] Field Day Ops and G-76 Generator

[Ray Fantini]

LM-2576T-12 will give +12 at 3A or so with a couple capacitors, a 100 uH coil and a 1N5822 Schottky diode and will work with anything from 10 to 40 VDC input. Way better than an inefficient series LM-317 where you are wasting power in generating heat. Coming from 24 VDC down to 12 VDC with series regulation you will be dissipating an equal amount of energy as heat in a series regulator, don’t think you need the heat in the summer. The switching regulator generates very little heat and will require less work on the cranking end.
Also Midwest Surplus has these switching supplies that I bought for under ten bucks that are 24 VDC input and rated at 15 VDC output but appear to be adjustable and if I get the time will try seeing what they can do in term of different DC inputs and a 13.5 VDC output. They are rated at 5 Amps service. My idea was to throw one into a green box and use it on the jeep for a twelve volt source for the computer and modem.

Ray F/KA3EKH

From: MRCA [mailto:mrca-bounces at mailman.qth.net] On Behalf Of B. Smith
Sent: Thursday, June 23, 2016 10:30 AM
To: mrca at mailman.qth.net
Subject: [MRCA] Field Day Ops and G-76 Generator


      This week end  has an excellent wx forecast and temps in the low 80's so I will again deploy for the annual ARRL Field Day Operations mainly on 80 and 40 CW. Call sign used will be K4CHE/3   -     I have to use slant 3 because no one can figure out what DE means when I send the ARRL section.   :-(   The plan is to go all "natural power" but without batteries. So it will be strictly solar and "cranked" generator power.

     The plan is to evaluate  several items one of which  is using 300 ohm twin lead for feeding my antenna instead of the larger open wire line. Al N3FRQ made me a gift of a reel of this wire several years ago but I have experienced  matching problems in the past but will try a different balun this year.  I also will evaluate the   "hand cranked" G-76 generator which I have converted  to "foot pedal" operation.    Photo attached.  The problem that now presents its self is  pedaling and keying CW at the same time but I used to fly jets so I should be able to figure it out.   :-)      But I have to keep in mind that my  ops with a straight key is marginal anyway as anyone on the Sunday night MRCA CW net can attest but we hope to make several contacts. During receive  if I get tired of pedaling I will use a smaller British Clansman set.

     The G-76 was designed for 24-30 volt ops and mainly to power equipment such as a PRC-70 or charge a ni-cad battery. By slow cranking  we can generate  an output in the 20 volt range but I still have to drop the voltages for my 12-14 volt low power equipment such as the SGC-715 and TRC-77. I hate to waste the power with a low voltage regulator but have not come up with a better idea. Perhaps someone has a suggestion. I all ready have the regulator LM317 chassis built  as I utilized  the same assembly  for the solar panels in the past. In front of the regulator I have a couple of very large capacitors to smooth things out.
Any suggestions?
             Z

[cid:image001.jpg at 01D1CD3E.20F3F3A0]
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.qth.net/pipermail/mrca/attachments/20160623/92d69ac4/attachment-0001.html>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.jpg
Type: image/jpeg
Size: 114543 bytes
Desc: image001.jpg
URL: <http://mailman.qth.net/pipermail/mrca/attachments/20160623/92d69ac4/attachment-0001.jpg>
-------------- next part --------------
A non-text attachment was scrubbed...
Name: IMG_0175.JPG
Type: image/jpeg
Size: 2135525 bytes
Desc: IMG_0175.JPG
URL: <http://mailman.qth.net/pipermail/mrca/attachments/20160623/92d69ac4/attachment-0001.jpe>