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<div class="moz-cite-prefix">On 11/16/2014 1:34 AM, Doug Crompton
wrote:<br>
</div>
<blockquote cite="mid:BLU172-W471BCDB3417DDBF8D6962FBA8A0@phx.gbl"
type="cite">
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<div dir="ltr"><font style="" color="#000000"
face="Tahoma,sans-serif">I suppose any of those items could be
true in about 5% or less of the situations encountered by the
average Allstar user.</font></div>
</blockquote>
<br>
<br>
Since you said user, and not operator, let's put that into
prospective. Most every transmitter on WAN uses direct FM, the same
goes for the WIN system. These two systems make up a whole lot more
than 5% of the AllStar users. You are generalizing and comparing
apples to oranges. Even if you really meant operators, your math
isn't close to reality.<br>
<br>
<br>
<blockquote cite="mid:BLU172-W471BCDB3417DDBF8D6962FBA8A0@phx.gbl"
type="cite">
<div dir="ltr"><font style="" color="#000000"
face="Tahoma,sans-serif"> For the average user a standard FOB,
whether it be DMK or modified Chinese, works just fine.</font></div>
</blockquote>
<br>
<br>
Again, that depends on what exactly the average user is doing. If
he's using MIC audio only - yes. If he's also using channel B and
dumping PL into the modulator to get good sub-audible, then a
standard FOB job isn't fine.<br>
<br>
<br>
<blockquote cite="mid:BLU172-W471BCDB3417DDBF8D6962FBA8A0@phx.gbl"
type="cite">
<div dir="ltr"><font style="" color="#000000"
face="Tahoma,sans-serif"> I don't want people to get the idea
this is going to do something special for them and they need
to spend the extra money and buy it. </font></div>
</blockquote>
<br>
<br>
And I don't want people to think they can get by with a $2.00 FOB
when they need the additional circuitry of a better device.
Education is what is needed here, not some half-cocked response that
doesn't take into account all of the circumstances of the
situation. <br>
<br>
<br>
<blockquote cite="mid:BLU172-W471BCDB3417DDBF8D6962FBA8A0@phx.gbl"
type="cite">
<div dir="ltr"><font style="" color="#000000"
face="Tahoma,sans-serif">Most all radios have TX timeouts so
that point is taken care of. </font></div>
</blockquote>
<br>
Time out timers in radios? You aren't serious? I don't know of any
situation were I would knowingly enable a TX timer 'on the radio'.
That surely wouldn't fly on our network.<br>
<br>
<br>
<blockquote cite="mid:BLU172-W471BCDB3417DDBF8D6962FBA8A0@phx.gbl"
type="cite">
<div dir="ltr"><font style="" color="#000000"
face="Tahoma,sans-serif">The other issues don't apply to most
radios. </font></div>
</blockquote>
<br>
<br>
Again, you are generalizing. There are plenty of folks that hack
into the radios circuitry to get adequate deviation, especially on
PL tones. <br>
<br>
<br>
<blockquote cite="mid:BLU172-W471BCDB3417DDBF8D6962FBA8A0@phx.gbl"
type="cite">
<div dir="ltr"><font style="" color="#000000"
face="Tahoma,sans-serif">I don't understand the cos/ctcss one
because like PTT this is SW switchable.<br id="FontBreak">
</font></div>
</blockquote>
<br>
<br>
Just because the logic state is switchable in software doesn't
guarantee that it will be properly recognized by the hardware. The
two logic states are logic high and logic low. The FOB requires a
logic low (a pull to near ground potential) because the logic the
device is looking for was supplied by a hardware switch to ground.
The maximum voltage on the GPIO's is 3.3 V, that's why the Schottky
diodes exist. The thing you have to remember is that many radios
supply a positive logic source and they may not have the ability to
source a low. This situation happens where the device in the radio
is a PNP transistor or other active high circuit, and while it has
the ability to pull to a high, but cannot source a ground without a
pull-down resistor. Pull down's can be a problem and is why Mark
Herson commented on why he prefers to have a pull to +5 so when the
system is protected by an incorrect COR condition if the radio is
turned off or otherwise disconnected. <br>
<br>
<br>
<br>
<blockquote cite="mid:BLU172-W471BCDB3417DDBF8D6962FBA8A0@phx.gbl"
type="cite">
<div dir="ltr"><br>
<font style="" face="Tahoma,sans-serif">Most hams are cheap and
building, modifying etc. are a large part of our hobby.</font></div>
</blockquote>
<br>
<br>
You are generalizing again. Many (most?) hams cannot do the
modifications to the FOB's. Out of the 13 core members of the WAN
system, 3 of them have the ability to do FOB modifications. The
others wouldn't even consider it.<br>
<br>
<blockquote cite="mid:BLU172-W471BCDB3417DDBF8D6962FBA8A0@phx.gbl"
type="cite">
<div dir="ltr"><font style="" face="Tahoma,sans-serif"> We usually
don't put dollars and cents on our time. It's the fun of doing
it. Anyone can buy something and throw it on the air. Everyone
has to make the decision what's best for them. <br>
</font></div>
</blockquote>
<br>
<br>
Misinformation destroys a hobby. Education is best, but getting
people to read and understand what it takes to make an educated
decision isn't easy. Believe me, I know. I have authored hundreds
of articles on this hobby.<br>
<br>
<blockquote cite="mid:BLU172-W471BCDB3417DDBF8D6962FBA8A0@phx.gbl"
type="cite">
<div dir="ltr"><font style="" face="Tahoma,sans-serif"><br>
The FOB mod I described in the how-to on the web page is
really a piece of cake. All you need to do is solder some
wires on the FOB and build a minimal amount of external
circuitry. I made it harder (mechanically) because I put it in
a nice box which is not necessary. For $10 or less worth of
parts and a few hours of your time you have an interface.</font><br>
</div>
</blockquote>
<br>
<br>
While I agree that you have an interface, that interface doesn't
take into account every installation. The URI and RIM handle the
extra LPF'ing needed when driving a modulator directly. The RIM has
buffer circuitry on the COS and PL inputs to take whatever the radio
can give it, and convert it to a solid pull to ground, just the the
mechanical switch the CM108/119 was designed for. Your $2 FOB will
not work with all types of radios. You have to know what you need
and source the equipment accordingly. <br>
<br>
The RIM isn't some poorly thought through copy of a URI. It has
additional circuitry for those instances where they are required. I
have nothing against the URI. I have more of them deployed than any
other radio interface. I simply got tired of having to put a
resistor divider in the discriminator line to get the audio in range
of the software, adding amplification beyond the ability of the URI
to sufficiently drive the modulator, and putting transistor
switching in between the radio and URI so the hardware inputs worked
reliably. Nothing more, nothing less.<br>
<br>
Whether a user of this technology needs the special things the
commercial interfaces provide depends on the situation, and making
generalizations doesn't help. I'm sure you are proud of your work
converting a FOB, but understand there are fewer hams than you might
expect with the skills and equipments needed to do a successful FOB
job.<br>
<br>
Kevin<br>
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