[Johnson] 250-37 directional coupler

[steveac at charter.net]

Thanks Jim and Cal for the explanation.

Jim . . . it would be great to have a copy of the manual for the KW Matchbox. I'd be happy to pay you for postage and copy costs.

Thanks and 73,

Steve K8JQ

---- "James M. Walker" <chejmw at acsu.buffalo.edu> wrote: 
> Some of the meters used were, 0-250uA and 0-1 Ma.
> For better sensitivity at low power, a 0 - 100uA meter is
> recommended. The directional coupler samples the RF
> flowing to and from the antenna circuit, IE into the MB
> and reflected back to the transmitter.
> 
> There is a dropping resistor in the sample circuit on both
> sides, to limit the current to the meter. It uses a matched
> pair of rf diodes to rectify the sampled RF.
> 
> ARRL handbooks from the middle 1950s to middle
> 1960s had similar circuits in them.
> 
> Do you have the manual pages for the Matchbox, or
> would you like them?
> Jim
> WB2FCN
> http://eshop1.chem.buffalo.edu 
> 
> ----- Original Message ----- 
> From: "C E" <catman351 at yahoo.com>
> To: "Steve" <steveac at charter.net>; <johnson at mailman.qth.net>
> Sent: Tuesday, June 13, 2006 9:10 AM
> Subject: Re: [Johnson] 250-37 directional coupler
> 
> 
> > Hi Steve:
> > I think you can go to the ARRL handbook and find a
> > directional coupler that will take the place of the
> > '37. The coupler (if what I think is right) rectifies
> > and turns the sampled rf into a DC level and sends it
> > out to the meter for your SWR or relative power meter
> > reading. Cal. N6KYR/8
> > 
> > --- Steve <steveac at charter.net> wrote:
> > 
> >> What is the output of the 250-37 directional
> >> coupler?
> >> 
> >> Is it a sample of the RF signal?
> >> 
> >> If so, what is the level of the sample as compared
> >> to the main signal?
> >> 
> >> Thanks.
> >> 
> >> Steve K8JQ