[time-nuts] Re: Re: Allan Deviation of Z3801A

John Ackermann N8UR jra at febo.com
Thu Jul 28 13:03:26 EDT 2005

Tom Van Baak wrote:
> Hi Lymex,
> A DBM is a standard RF component, so I
> don't think it's something you would build.
> HP made them years ago (HP 10514A) and
> companies like Mini-Circuits still do; in great
> variety and quantity. See, for example:
> http://www.minicircuits.com/dg03-102.pdf
> http://www.minicircuits.com/mixer.shtml
> This will tell you how they work:
> http://www.minicircuits.com/appnote/mxr1-25.pdf
> I assume you have a good local source for
> new or used electronic components. A DBM,
> old or new, should not cost very much.
> For a photo of the old HP 10514A DBM see:
> http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=7534160664
> /tvb

Actually, a DBM is just a small handful of components and it's not too 
difficult to build one (lots of ham projects use them, and those are 
often built from discrete components), but building a *good* one can be 
a bit tougher -- you need closely matched diodes of the right type and 
careful construction techniques.

Limex, if you can find one, a copy of the ARRL Handbook should give you 
examples of homebrew DBM circuits.

The bottom line is that it's usually easier, and if your time is worth 
anything, much cheaper, to buy one from Minicircuits (who, by the way, 
are pretty good about selling single-unit quantities to hams and I 
presume other experimenters).


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