Thanks, Steve. I'd have thought that putting the tuner in bypass
during receive would be problematic in terms of received signal
strength, but if local coverage is the objective perhaps this isn't
an issue.
A multiband antenna, as I mentioned in a previous post, would be an
alternative. Multiband verticals are inexpensive and omnidirectional;
with a poor ground, they should give you reasonable local coverage
and eliminate the need for a fast tuner as well as the azimuthal
nulls that a low dipole might produce.
73,
Dave, AA6YQ
--- In digitalradio@yahoogroups.com, Steve Hajducek <[EMAIL PROTECTED]>
wrote:
> Hi Dave,
>
> The ALE scan rates are 1, 2, 5 channels/second for NORMAL ALE with
> AQC-ALE being locked at 5 ch/sec. In the latest MIL-STD-118-141B
> standard, they state a future goal is 10 ch/sec.
>
> The only need for any use of ATU tuning is when you go into
transmit.
> The ATU should be in BYPASS on RX. Most of the internal radio ATU
> designs that have been around for a while are tool slow to tune for
> optimum ALE network operation when TX is required, however the
entire
> ALE network can be configured to support the worst case station in
> the network. You see if your station is Scanning and I place an LQA
> Call to it, my station will start transmitting on the best LQA
ranked
> (best SNR/BER channel) and with our settings correct and you
station
> being active and not otherwise engaged, you should here my station
> calling yours and then respond within x amount of time. The
standard
> for that response time is 2 seconds, thus any use of antenna tuning
> (Steppr antenna etc) or ATU tuning tone, amplifier tune up etc.
must
> a be done within 2 seconds so that my station hears your
responding,
> else my station will then call you again on the same channel or
move
> to the next best LQA ranked channel depending on ALE configuration
> options on my end, the basic ALE hardware controller is going to
just
> move to the next LQA channel, which is what the current PC-ALE and
> MARS-ALE do, but that going be changing in both tools.
>
> So your station only needs to activate your ATU if being used
before
> the TX and only needs to tune on the first TX on the new channel
> being TX'ed on, some ham ATU's are going to re-tune on all applied
> RF, that's poor, all ATU need to be in BYPASS until the channel
being
> transmitted on comes into play else you have receiver attenuation
the
> further away you move from the last TX channel, this rules out a
slew
> of ATU designs. I approached LDG about an ATU design geared for ALE
> and the result was the AT-200PC which is based on their earlier
> AT200PRO. With this computer controlled only unit, once trained for
> the channels being used, RF is never needed for a re-tune unless
the
> characteristics of the antenna change and the stored settings in
> memory are invalidated. For Scanning the unit is placed into BYPASS
> and a split second before TX is placed back in line the frequency
to
> be used is sent to the ATU and its instantly tuned to the last used
> settings for that antenna on that antenna port. The AT200PC has two
> antenna ports that are selected on a channel by channel basis by
> MARS-ALE when scanning so that a combination of a NVIS and Skywave
> antenna can be used if the scan group transcends both ranges or
other
> reasons like you use a 160m dipole on that band and a broadband
> antenna 80m and above, you can also pop an LDG DTS-x ANT SW on the
> ANT port 1 of the AT200PC and have 4 or 6 antenna ports if you need
> that or add an ACOM 2002A 10 port switch. Also, on a channel by
> channel basis you select which channels need to use the ATU, for
> example, my 400 foot 12 gauge Random Wire antenna feed off a 2
stage
> 9:1 RF transformer grounded on one side on the output needs no
tuning
> above 4Mhz, so only the channels below 4Mhz have the ATU enabled.
> This is also applied to the CAT radios that support enough internal
> ATU and ANT port control in MARS-ALE. The addition for support for
RF
> amplifiers is pending. The Steppr antenna support is also pending,
> they just handle the 1 ch/sec scan rate and fuzzy logic needs to be
> applied as to when to re-tune on RX based on frequency step from
last
> use etc., I am still not sure so about supporting them.
>
> /s/ Steve, N2CKH
>
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