[time-nuts] GPDSO Distribution amp that does not radiate ?

[Bob kb8tq]

Hi

Running and shielding a 10 MHz standard signal is never easy. Ground loops
here or there are highly likely to exist and create all sorts of issues. In some 
setups, -10 to -20 dbm is not an uncommon result ( = fix the termination on 
your Spectracom system …). Getting below -90 is actually doing pretty well.

Bob

> On Jul 13, 2019, at 12:53 PM, Jerry O. Stern <jsternmd at att.net> wrote:
> 
> I have been using a Tbolt and TAPR TADD-1 for a few years, mainly as an
> external reference source for my workbench equipment.  Just got a SDR radio
> kit (Ubitx) and trying to calibrate the local oscillators found this
> annoying substantial 10MHz signal heterodyning with the LO's (45MHz and
> 12MHz).   Taking a look on my SA with just a broad band telescopic antenna
> in the SA input, I see a 10MHZ at about -55 dBm and no other signals > -120
> dBm.  The Tbolt is about 4-5' away from the workbench BUT I disconnected
> everything and it is only connected to the TADD-1 distribution amplifier
> The TADD has no distribution coaxes attached, it is in the TAPR metal
> cabinet which I always thought was well shielded and every port has been
> terminated with 50 Ohm  dummy load plugs.  When I take the TADD-1 out of the
> equation and just run the Tbolt into a 50 ohm termination plug, the 10MHz
> signal on my SA drops down to  > -90 dBM.     I duplicated this with a
> Lucent RFTGm-Xo/Rb pair and the TADD-1 with similar results.    Has anyone
> else seen this with their distribution amp?
> 
> 
> 
> Jerry 
> 
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