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eHam Forums / Elmers / Can I run a Mobile rig from a Cig Lighter ?
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on: January 06, 2008, 05:25:54 AM
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Take a look at the thickness of the wiring in your car then look at the poor contact arrangements in the cigarette lighter connectors. I would not like to pass more than five amps through such an arrangement.
Alan, K0BG has something to say about this on his website but I can't locate it right now.
HA6SST
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eHam Forums / Elmers / Antenna Switches using Industrial Relays.
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on: January 06, 2008, 05:20:30 AM
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They work fine on HF but struggle from 6m upwards. I replaced a damaged relay with a P&B unit in our club linear six months ago and it's still handling 600W of RF without complaining.
HA6SST
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4
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eHam Forums / Elmers / Spiral bound paper logbook
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on: January 01, 2008, 03:00:31 AM
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Half an hour with Open Office then off to the copy shop. They printed fifty double-sided sheets then bound them for me between some card covers.
If you want a copy of the speadsheet I used then email me at edwardalmos(at)gmail(dot)com
HA6SST
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5
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eHam Forums / Company Reviews / Mouser Electronics - Nice People
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on: December 29, 2007, 03:41:11 AM
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Apart from having tens of of thousands of items in their catalog Mouser can also source other items. They managed to find me some 74HCT9046 ICs but because it wasn't a standard part I had to supply a credit card # and submit a manual order. I was therefore quite surprised when Mouser telephoned me here in Hungary to get the information they needed. Not only that, they will only be charging my card at the end of January when the chips ship. Nice people. http://www.mouser.comsales@mouser.com (USA) eusales@mouser.com (European Union) HA6SST |
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8
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eHam Forums / Elmers / Power supplies in series
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on: December 24, 2007, 06:13:17 AM
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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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9
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eHam Forums / Elmers / Power supplies in series
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on: December 24, 2007, 06:12:34 AM
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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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10
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eHam Forums / Elmers / Plasma TV RFI
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on: December 21, 2007, 01:24:25 PM
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A friend of mine has reduced RFI from flat panel sets by completely wrapping them in several layers of aluminum foil and then grounding the foil to multiple earth spikes. The only downside is that picture quality is affected and the remote control may no longer work*.
The original plasma TV sets were horrible RFI sources and some hams have reported S9 plus noise as soon as their neighbor turned on his plasma set. Things MAY have improved with plasma TVs but the good news is that most flat panel TV screens are now LCD which produces much less RFI.
HA6SST
*Don't try this at home!!
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11
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eHam Forums / HomeBrew / AC voltage divider
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on: December 04, 2007, 01:07:30 PM
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Grab an old mains transformer and strip it down. Then you wind a new transformer with 240 turns on the primary and 180 turns on the secondary. Use slightly heavier wire for the secondary.
HA6SST
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12
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eHam Forums / Company Reviews / Modelfixings.co.uk
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on: December 01, 2007, 12:43:48 AM
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I have included this company in the review section because they offer a good range of tools and hardware including bearings, taps and dies. I ordered a 10-32 UNF* tap on the Tuesday and it was with me on the Friday, despite a 1200 mile journey and the delays of the Christmas post. They also answer email queries quickly, I received a reply in two hours to an email sent at 7pm. Web site: http://www.modelfixings.co.uk/index2.htmEmail: info@modelfixings.comHA6SST *When ARE you guys going to go metric? |
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eHam Forums / HomeBrew / Frequency Offset in Homebrew Phasing Transceivers
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on: November 15, 2007, 01:31:36 PM
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There are two options to generate a CW signal when you have a phasing transceiver. Option one is to generate a very clean sinewave at (for example) 700 Hz then feed this into the modulating stages. Option two is to apply a keyed DC bias to the balanced modulators and this will generate a carrier.
Experimental Methods in RF Design has details of this but they do not mention the offset problem.
HA6SST
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14
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eHam Forums / HomeBrew / Frequency Offset in Homebrew Phasing Transceivers
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on: November 13, 2007, 12:54:59 AM
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OK, I need some help here. When using a homebrew transceiver based on a BFO and filter(s) it's easy to work out where you need to tune to work a station. You alter the VFO until the voice sounds about right then you give them a call, the BFO which is offset from the carrier does all the work.
What happens if your rig uses phasing for SSB/CW reception?
Let's use CW as an example. I tune around and find station W1XYZ. With my rig in USB mode (there is no CW mode in a phasing rig) I alter the VFO until I get a pitch which sounds comfortable, in my case about 700 Hz. Looking at the rig I see that the frequency display reads 14.005. Should I then transmit on 140043, 14.005 or 14.0057 so that he can hear me?
HA6SST
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