[amsat-bb] lindenblad observations

[francesco messineo]

Good morning all,

even if this setup probably won't be used by anyone I thought I'd
share my findings.

I've built a couple of lindenblads following the AA2TX articles. The
EZ-lindenblad for 2m and the parasitic lindenblad for 70cm. This is
for a 2 week temporary location in IS0 (JM49MG).
Both antennas have been made with locally available hardware, not very
far from original design anyway. The biggest difference is perhaps the
parasitic elements for the 70 cm one which have a 4mm diameter instead
of approximately the 3mm of original design.
Both antennas are on the same pole, 1.5 meters apart and not very far
from the roof (< 1m the 2m one), they have however a clear sky view.
Cable runs are quite long, 20m of rg-213 on both bands and no preamps.
Only RHCP versions made.
Rig is ft-847 with internal preamps on.
In 4 days I have tried almost all LEOs (but AO-16 and AO-27 which are
non operational afaik).

DO-64: never heard anything (is it operational?)

AO-51: 435.300 output can be heard at times, some callsing can be
undestood, never quieting the receiver. FM uplink in europe is too
crowded to attempt any try at txing. 435.150 output is much lower than
the 435.300 one, only rarely it can be heard but when it's heard I can
hear myself briefly from the USB uplink. Obviously no contact is
possible.

SO-50: usually can't be heard, sometimes during a pass on positive
QSBs the downlink can be heard very noisy and for a short time (so far
only copied a full callsign).

AO-07: downlink on mode B can be heard quite easily down to 3 degrees,
uplink is next to impossible (50W out of the rig, CW only of course)
but probably depends on the high level of power used in europe as
during a pass over the atlantic and part of brazil I could hear my own
signal down to 3 degrees and I couldn't hear any other signal. No
contacts have been made, so far only heard my own signal a few times
and very low (maybe the 432 MHz uplink is too far out of the optimal
passband of the 435 MHz lindy?)

FO-29: downlink can be heard, not very strong but workable, uplink is
sometimes difficult but a lot easier than AO-07. No contacts made so
far, have been calling CQ in CW for a few passes.

VO-52: downlink easy to copy as on AO-07, quite easy to hear my own CW
peaking at S3 during all passes over 5 degrees, no contacts made,
heard only a lot of SSB stations, this is the easier sat with this
setup.

ISS: never heard any signal so far.

I think I'll go back to the homemade V/U yagi "arrow" like on next
travels, that's a real performer on LEOs.

PS: the NB on FT-847 (first time using this rig) is quite uneffective,
motors on the street still make an audible signal when passing by,
it's attenuated but not like on all other rigs I know. Is there any
fix for it?

73
Frank IS0/IZ8DWF