I have been recommending the dummy loads and power attenuators from Ridge Equipment for years. They usually have a good selection, excellent quality and great prices. They will also provide a VNA plot for 10 bucks more as I recall. Remember that these loads usually have N connectors, so you may need an adapter.
73, Larry N8LP On 12/23/2011 6:48 AM, [email protected] wrote: > Date: Thu, 22 Dec 2011 14:29:14 -0800 (PST) > From: ab2tc<[email protected]> > Subject: Re: [Elecraft] K3 + LP100A + Dummy Load > To:[email protected] > Message-ID:<[email protected]> > Content-Type: text/plain; charset=us-ascii > > Hi, > > I highly recommend the 75W dummy load from Ridge Equipment. I have one > permanently connected in my system. I believe it is a military surplus piece > of equipment with absolutely superior characteristics like an SWR at 500MHz > of 1.05 or less. It has no problem with 100W for a minute or less for sure. > > AB2TC - Knut > > > Phil, > > All dummy loads are not created equal. Connect yours directly (no coax) > to the LP-100 or an antenna analyzer to determine its characteristics > with frequency (I assume Larry calibrated your LP-100 to NIST > standards). A common ham dummy load is something to tune your amplifier > into and use for general purposes. If you are going to do measurements, > you will need something more like lab quality dummy loads. > > Both your dummy load and the 6 feet of RG8X will show a frequency > dependency since you do not have a precision 50 ohm dummy load. A > transmission line that is not terminated in its characteristic impedance > acts like an impedance transformer, and that transformation ratio is > frequency dependent. > > If you want a dummy load that is flat WRT frequency and suitable for > instrumentation use, take a look at the Caddock 50 ohm Thick Film > Resistors - they are available up to 100 watt rating. You must use them > on a heat sink, and keep the leads as short as possible, and you will > have a precision dummy load. Caution - even with the heat sink, do not > exceed their power ratings, they will go open circuit in an instant. > I use several of those as instrumentation precision loads. > > Other sources of precision dummy loads is Ridge Equipment - > https://www.ridgeequipment.com/store/dummyloads.html. They have one > rated at 75 watts for $12 and one rated at 15 watts for $7.50 - those > are quite good for instrumentation purposes. > > 73, > Don W3FPR > > <snip > </quote> ______________________________________________________________ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:[email protected] This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
