A new impedance calculator for RF inductors on ferrite cores

Some time ago I published a calculator for estimating the impedance of RF inductors on toroidal ferrite cores (Calculate ferrite cored inductor). The calculator (input form above) use the core dimensions and complex permeability as the basis for calculation. There are some popular cores that are not simple toroids and so not suitable for direct … Continue reading A new impedance calculator for RF inductors on ferrite cores

Accuracy of AIMuhf system – AIM865A vs AIM882 on a ferrite cored inductor

In other posts, I have commented on the apparent inconsistency of AIMuhf measurements. One of the devices I often wish to measure is a ferrite cored choke such as those used for a Guanella 1:1 balun. A small test inductor was made to provide a common device for measurement across instruments, and versions of software, … Continue reading Accuracy of AIMuhf system – AIM865A vs AIM882 on a ferrite cored inductor

Sevick’s comments on selection of ferrite mix

(Sevick 2001) discusses efficiency of transmission line transformers that use nickel-zinc ferrites in Chapter 11 “Materials and power ratings” applied to broad band baluns. In Chapter 11 he reports a range of measurements of two different basic configurations, a 4:1 Ruthroff balun and a 4:1 autotransformer and uses nickel zinc ferrite cores of types that … Continue reading Sevick’s comments on selection of ferrite mix

Attempting to reconcile W5DXP & G3TXQ’s comparison of K and 52 mix ferrites

Steve (G3TXQ) posted a graph comparing Cecil’s (W5DXP) measurements of two turns on FT240-52 and FT240-K. It is interesting to reconcile the #52 curves with Fairrite’s datasheets. A simple reconciliation is to compare results at the frequency where µ’ and µ” curves cross over. Last update: 12th October, 2015, 8:50 AM

Ferrite K mix

Among forum experts, there are ready recommendations for the ideal ferrite material (or mix) for a balun, often without knowing any detail of the application. The ‘magic’ mixes include K. Perhaps they are devotees of Sevick. Over some years I have searched for manufacturer’s data on K mix, and found only two references: Amidon who … Continue reading Ferrite K mix

N6THN’s novel balun – flux leakage

N6THN’s novel balun presented measurement of the Insertion VSWR of the subject balun, and N6THN’s novel balun – an explanation gave explanation that included mention of flux leakage as a contributor to the quite high inductance per unit length of the transmission line formed by the two windings. A correspondent suggested that with a ferrite … Continue reading N6THN’s novel balun – flux leakage

Comment on KN5L on balun CMRR – coax example

One of the ham fashions of proposed solutions to characterising a balun is to find the Common Mode Rejection Ratio (a term carried over from other applications, eg voltage driven operational amplifiers). (Anaren 2005) explains a method of finding balun CMRR. Anaren gives a definition of CMRR: Common Mode Rejection Ratio is defined and the ratio … Continue reading Comment on KN5L on balun CMRR – coax example

Low power Guanella 1:1 balun with low Insertion VSWR using a Fair-rite 2×2631540002 – measurement of Zcm

Low power Guanella 1:1 balun with low Insertion VSWR using a pair of Fair-rite 2631540002 suppression sleeves – design workup presented a desk design of a low power balun. This article presents measurement of common mode impedance Zcm of a prototype using a nanoVNA. Above is the prototype 2631540002×2 wound with 3.5t of RG316. Last … Continue reading Low power Guanella 1:1 balun with low Insertion VSWR using a Fair-rite 2×2631540002 – measurement of Zcm