Thanks to all for the thoughtful comments! A special thanks to Nick for suggesting an antenna problem, because that's exactly what it was.

When I put the 58503Bs in their new location I reconnected the two antenna cables to the 4-port distribution amplifier but inadvertently did not connect either of the two 58503B antenna cables to the antenna power pass-through port. In my defense, the amplifier was tucked behind the 58503Bs so I wasn't able to see the port labels.

After fixing the cabling, both units completed their surveys and are now happily locked.

Tom, thanks for the suggestion about recording the SYST: STAT? data for future reference. Now that everything is back in order, I've done that.

Regards,
Stan

I ended up doing pretty-much exactly this due to running multiple GPS receivers and antennas.

I found a GPS Networks RMALDCBS1X16 for an insanely good deal on eBay (it ended up costing the same as a 3 port Symmetricom/HP splitter, and I had rack space available for it) and I now use that to power my primary antenna. I can plug up to 16 receivers in and not worry about which one is powering the antenna, which is handy since I currently have 4 active receivers attached to my main feed.

It’s overkill for my needs, but given how much space there is inside that 3U case, I’ve been pondering putting some active monitoring in place that would automatically switch between the antennas based on signal strengths and general availability (live failover if the primary antenna goes down). However, I am not an RF engineer, so this seems a bit out of my league atm :D.

Nick

On Feb 3, 2025, at 07:31, Bob Camp via time-nuts time-nuts@lists.febo.com wrote:

Hi

I can’t count how many times I’ve done pretty much the same thing.

I finally gave up on doing a “pass through” bias to the antenna. Disconnecting this device / moving cables created issues pretty much forever.

One solution is a dedicated bias Tee to feed the amp (if you have one) and the antenna. All of the GPS gizmos are DC blocked. This approach also takes care of the gotcha of 3.3V output GPS gizmos feeding amps or antennas that want a 5, 7 or 12V feed.

Bob

On Feb 3, 2025, at 8:25 AM, Stan via time-nuts time-nuts@lists.febo.com wrote:

Thanks to all for the thoughtful comments! A special thanks to Nick for suggesting an antenna problem, because that's exactly what it was.

When I put the 58503Bs in their new location I reconnected the two antenna cables to the 4-port distribution amplifier but inadvertently did not connect either of the two 58503B antenna cables to the antenna power pass-through port. In my defense, the amplifier was tucked behind the 58503Bs so I wasn't able to see the port labels.

After fixing the cabling, both units completed their surveys and are now happily locked.

Tom, thanks for the suggestion about recording the SYST: STAT? data for future reference. Now that everything is back in order, I've done that.

Regards,
Stan

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I would think one could use a cheap module as a "signal strength/quality" monitor, with a suitable power dividers to provide isolation between module and your 58503s.
Some software could monitor the output of the modules to figure out which one is "best" according to some metric. 
 

On Wed, 5 Feb 2025 06:41:46 +0000, Purplxed via time-nuts time-nuts@lists.febo.com wrote:

I ended up doing pretty-much exactly this due to running multiple GPS receivers and antennas.

I found a GPS Networks RMALDCBS1X16 for an insanely good deal on eBay (it ended up costing the same as a 3 port Symmetricom/HP splitter, and I had rack space available for it) and I now use that to power my primary antenna. I can plug up to 16 receivers in and not worry about which one is powering the antenna, which is handy since I currently have 4 active receivers attached to my main feed.

It’s overkill for my needs, but given how much space there is inside that 3U case, I’ve been pondering putting some active monitoring in place that would automatically switch between the antennas based on signal strengths and general availability (live failover if the primary antenna goes down). However, I am not an RF engineer, so this seems a bit out of my league atm :D.

Nick

On Feb 3, 2025, at 07:31, Bob Camp via time-nuts  wrote:

Hi

I can’t count how many times I’ve done pretty much the same thing.

I finally gave up on doing a “pass through” bias to the antenna. Disconnecting this device / moving cables created issues pretty much forever.

One solution is a dedicated bias Tee to feed the amp (if you have one) and the antenna. All of the GPS gizmos are DC blocked. This approach also takes care of the gotcha of 3.3V output GPS gizmos feeding amps or antennas that want a 5, 7 or 12V feed.

Bob

On Feb 3, 2025, at 8:25 AM, Stan via time-nuts  wrote:

Thanks to all for the thoughtful comments! A special thanks to Nick for suggesting an antenna problem, because that's exactly what it was.

When I put the 58503Bs in their new location I reconnected the two antenna cables to the 4-port distribution amplifier but inadvertently did not connect either of the two 58503B antenna cables to the antenna power pass-through port. In my defense, the amplifier was tucked behind the 58503Bs so I wasn't able to see the port labels.

After fixing the cabling, both units completed their surveys and are now happily locked.

Tom, thanks for the suggestion about recording the SYST: STAT? data for future reference. Now that everything is back in order, I've done that.

Regards,
Stan

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