Singal get lost frequently when HRM was enable, when he closed, it run normally.
Hope everyone can help to double confirm. It will be a great hint to resolve the problem.
I did a 3-hours-run this morning with GH625, GH505 old GPS-FW, GH505 new GPS-FW.
Distance of GH625 was 32,48 km,
GH505 with old GPS-FW was 33,08 km (0,6km longer),
GH505 with new GPS-FW lost GPS-signal at 21 km, did get it back a few times until it showed 24,41 km. Then it didn´t refix anymore.
Resume: The distance of GH625 is nearest to the real distance.
GH505 with old GPS-FW has bad accuracy. But this is different during the run. Most times distance of GH505 is longer than distance of GH625, but sometimes it is getting nearer to to distance shown at GH-625 again. If GH625 measures with the littlest error, this means, GH505 measures to long mostly but sometimes shorter distance than it is in real. This can be also watched at straight tracks!
GH505 with new GPS-FW failed but it is possible it has an other defect and not depends on HR disable / enable.
HR was set to "No" in accessories-menue at both GH505.
I did have runs with GH-505 with HR enabled without loosing GPS-fix.
I´ll continue testing this. But I think HR is not the cause of the problems, but this is only a feeling.