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1996-08-07
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Newsgroups: rec.radio.amateur.misc
From: jonathan@nova.decio.nd.edu (Jonathan Bradshaw)
Subject: Kenwood TH28A Mods (here they are)
Message-ID: <1992Oct5.223344.26956@news.nd.edu>
Sender: news@news.nd.edu (USENET News System)
Organization: University of Notre Dame, Notre Dame
Date: Mon, 5 Oct 1992 22:33:44 GMT
Lines: 63
I just got the following. I CANNOT VERIFY THIS. However I do know the
aircraft (hold F down then LOW) toggle does work.
From: LAIRDPG@lub001.lamar.edu
Subject: Re: TH28A mods? Anyone?
Date: Sun, 16 Aug 92 19:59:26 PDT
TH28A Mods:
1) Remove the 4 screws holding the radio together.
2) With your finger in the battery bay, separate the two parts.
3) The inside of the keypad case has a copper RF shield. Move this shield
out of the way by removing the 2 screws and bending it up and away from
the PC board. (There may be double sticky tape holding the shield to
the IC.) Under the shield you will find a large IC surrounded by
an array of diodes, as follows:
+-------+
| |
| IC |
| |
D D D D +-------+
1 1 1 1
5 4 3 2
D D D D
1 1 9 8
1 0
(The diode numbers are read vertically.)
NOTE: Diodes D15 & D14 are NOT present in the American version.
4) Remove diodes D8 and D10.
5) Install one of these diodes in D14.
This enables the following three extended modes:
1) Extended receive from 360 Mhz to 400 Mhz.
2) Extended receive from 400 Mhz to 520 Mhz.
3) Extended transmit/receive from 136 Mhz to 174 Mhz.
in addition to the existing aircraft frequencies of:
4) Receive from 118 Mhz to 136 Mhz. (AM)
(AM and FM are switched automatically according to the frequency range.)
To switch between the modes, press the [F] key for one second, then
press the [LOW] key. This will switch between:
a) Amateur VHF band (136 Mhz to 174 Mhz).
b) 340 Mhz band (340 Mhz to 400 Mhz).
c) Aircraft band (118 Mhz to 136 Mhz).
To get the extended amateur UHF receive, press the [BAND] key while in the
136 Mhz to 174 Mhz mode.
--
Jonathan Bradshaw | jonathan@nova.decio.nd.edu -or- jbradsh2@darwin.cc.nd.edu
Packet: n9oxe@n0ary.#nocal.ca.usa.na | Prodigy: XMSN02B | (Os/2)(DOS)(Linux)
Newsgroups: rec.radio.amateur.misc
From: unbham@jupiter.sun.csd.unb.ca (UNB Amateur Radio)
Subject: Re: Kenwood TH28A Mods (here they are)
Message-ID: <1992Oct7.222626.199@jupiter.sun.csd.unb.ca>
Organization: University of New Brunswick
References: <1992Oct5.223344.26956@news.nd.edu>
Date: Wed, 7 Oct 1992 22:26:26 GMT
Lines: 49
In article <1992Oct5.223344.26956@news.nd.edu> jonathan@nova.decio.nd.edu (Jonathan Bradshaw) writes:
>I just got the following. I CANNOT VERIFY THIS. However I do know the
>aircraft (hold F down then LOW) toggle does work.
>
>
> D D D D
> 1 1 9 8
> 1 0
>
^^
>4) Remove diodes D8 and D10.
>5) Install one of these diodes in D14.
>
By just cutting diode 9, you enable the wide band receive on UHF
(from 400-520) and from 360-400 by hitting F and LOW.
I would be careful when cutting diode D10 out though, I did it
(I've done surface mount mods before) and my row 3 keys stopped working
(MEM, 3, etc) I am positive I didn't clip the wrong diode because I
clipped the connection leading out from the diode (you'll see what I
mean...)
Just don't get carried away, that's all..
>This enables the following three extended modes:
>
> 1) Extended receive from 360 Mhz to 400 Mhz.
> 2) Extended receive from 400 Mhz to 520 Mhz.
The above is available from the diode that I mentioned above. By the way,
the mods presented here hold some validity as they come from a tech sheet
that I got from the dealer.. a certain big mail order company down the states)
> 3) Extended transmit/receive from 136 Mhz to 174 Mhz.
>
>in addition to the existing aircraft frequencies of:
>
> 4) Receive from 118 Mhz to 136 Mhz. (AM)
This mod comes from simply holding down F and hitting LOW. If this is
all you want, don't cut anything.. I shudder at the thought at clipping
out surface mount diodes...
Derek
Newsgroups: rec.radio.amateur.misc
From: iain@vision.rs.ch (Iain Campbell)
Subject: Re: Kenwood TH28A Mods (here they are)
Message-ID: <iain-081092104913@talisker.rs.ch>
Followup-To: rec.radio.amateur.misc
Sender: news@neptune.inf.ethz.ch (Mr News)
Nntp-Posting-Host: talisker.rs.ch
Organization: Radio Schweiz AG.
References: <1992Oct5.223344.26956@news.nd.edu> <1992Oct7.222626.199@jupiter.sun.csd.unb.ca>
Date: Thu, 8 Oct 1992 10:16:28 GMT
Lines: 48
I bought a couple of TH28A's recently in the States and the guy in the shop
did the mods for me on the spot.
The features I have on the radios are those described by the recent
postings..
Rx AM 118.000 - 135.995
Tx/Rx FM 136.000 - 173.995
Rx FM 340.000 - 399.995 (Not 360-.. as in a previous posting)
Rx FM 400.000 - 519.995
Note: The poor thing does not like being tuned much over 500 MHz, it beeps
at you in complaint.
Here are the diode settings that are in my radios:
|
o o o o |
| | | | | I.C.
o o o o |
|_______________
o o o o
|
o o o o
I can therefore confirm that the above freq. ranges and the above diode
settings definitely work !!
Cheers,
Iain.
___________________________________________________________________________
Iain Campbell iain@vision.rs.ch
Radio Schweiz AG iain@dcs.glasgow.ac.uk
Laupenstrasse 18a
3008 Bern Tel: +41 (0)31 509 855
Switzerland Fax: +41 (0)31 509 675
___________________________________________________________________________