[Kenwood] Modified VHF/UHF rigs

[Dick]

Jay:

The problem is that the radios sold for ham use don't have the type
acceptance tag on them.  Therefore, they're not considered type accepted
for commercial use, even though they're the same radio.  Yes, they
probably would pass the tests, but the absence of the sticker makes
them illegal for commercial use.

Dick

----- Original Message ----- 
From: "Jay Eimer" <ad5pe at familynet.net>
To: <kenwood at mailman.qth.net>
Sent: 21 August, 2005 06:28
Subject: RE: [Kenwood] Modified VHF/UHF rigs



While that might be true in some cases, it isn't necessarily so.

I've seen HTs that were "repackages" of commercial HTs designed for 150MHz
public service - where they "blocked" tuning above 148 and relabeled them as
2m HTs.  Snipping the diode here (or whatever the mod is) makes them back in
to the public service HT they were designed to be, and they'd probably pass
type acceptance if that was possible.

But I've also seen HTs with band pass filters where what appears to be two
identical radios, with one tuning 144-148 and another for 150-154, that
"could" be changed from one to the other, but it would take changing a dozen
or more discrete components to different values do get the filters to
actually pass the signals.  I have two of these (70's era E.F. Johnson VHF
Public Service base radios) that were originally on 154.xxx.  A simple diode
snip opens them up.  A new ROM chip programs them for any freq from 137 to
174MHz.  But without changing the filter components, the harmonic
suppression goes out the window, and the intermod goes through the roof!  I
tried to mod one for 2m (was planning a repeater project at the time) and in
testing found the signals to be very wide, and very dirty.  I had to
re-engineer a significant portion of the Tx to get the spectral purity
within "good engineering practice" before I'd consider putting it on the
air.

If someone took the "ham" version of these radios and tried to put them on
public service, every department for 50 miles would be screaming about all
the "interference" (if they knew what it was).

On another note - I have a "modified" HF rig - it's pre-WARC, but barely.
It came from the factory with 30m receive but no transmit, and 2 "extra"
positions on the band switch.  All the filters are there.  It was a simple
mod to add 2 crystals for the BFO to get 12 and 17m, and remove one diode to
enable 30m.  So here's a legitimate "excuse" for a modified ham radio - to
enable "new" bands that the radio WAS designed for.  Not "out of band" as in
out of the specs for the radio (like marine band, etc.) but just to get on a
new band we are legal for.  More recently, 60m would be the same.  And look
at how many radios CAN'T be modded for 60m, because they use the "wrong"
bandpass filter and overheat.  My old Kenwood 440 modded for 60m just fine -
except that also made it (theoretically) DC to 30MHz.

73,
Jay


-----Original Message-----
From: kenwood-bounces at mailman.qth.net
[mailto:kenwood-bounces at mailman.qth.net] On Behalf Of Walter Daniels
Sent: Saturday, August 20, 2005 19:14
To: kenwood at mailman.qth.net
Subject: Re: [Kenwood] Modified VHF/UHF rigs

Actually Darrell, you are incorrect in that statement. The radios that are
able to be modified for out of band TX are designed to TX out of band or the
capability would not be in the radio to be brought out with a snip snip of a
diode. Most ham radios are designed for operation in many countries not just
the United States. In these countries they have different laws governing
radio operations . In many countries operating in these bands that are
illegal here are legal there so the radio manufacturers lock out the
functions that are illegal in the countries they are selling the radio in
hence the A and E designations on many radios with A being America and E
being Europe. So to be completely technical and in all honesty the radios we
buy here are already modified from the factory and hams unmodified them back
to original design specifications.

Wally


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