My ICOM IC-7300
In this sections I will describe my Tips, Mods,
and Experience with my new IC-7300.
First Page: 7300 AMP INTERFACING
Second Page: Bandpass Filters (BPFs)
This Page: WARNING about 3rd Party Mods (below)
This Page: Circuit diagram for using a RX-Only Antenna (below)
W A R N I N G :
There are/has-been two 3rd Party Modification Kits on the market which enable connecting an External RX Antenna to the IC-7300. These MUST NOT be used without external protection.
DOWNLOAD this PDF for more info:
Both of these kits may safely be used for connecting an external pre-selector, or external pre-amplifier to the 7300, but in order to safely use them for connecting an external RX-Antenna, you must provide a means of disconnecting the antenna during transmissions . . .
- otherwise you will likely damage the radio.
It is my understand that the INRAD kit has been discontinued. Do your own due dilligence.
NOTE: Installing either of these kits in your 7300 may void your warranty.
SAFELY USING A RX-ONLY ANTENNA with the 7300
There are a few mods available on the internet that suggest you can use them for connecting an external RX antenna.
DANGER: Unless you provide a means of disconnecting the antenna from the mod/receiver during transmit, you may very well destroy the downstream circuitry in the 7300.
The circuit below describes how to home-brew a safe circuit that inserts between the main antenna and the 7300 standard antenna jack.
- It uses a relay to switch between antennas when transmitting and receiving.
- It also has a manual switch to enable/disable use of the RX-only Antenna.
- It is shown with an optional pre-amplifier for the RX-Antenna, but you can leave it out if not needed.
- We are looking into identifying relays that are available and inexpensive. Stay tuned...
Drawing: G0IYQ & DJ0IP
DISCLAIMER: To the best of our judgement, this drawing is accurate. We have only designed it.
We have not built and tested it. BUILD IT AT YOUR OWN RISK. DO YOUR OWN DUE DILIGENCE.
ANT: The main station antenna
RX ANT: The RX-Only antenna
TCVR: Coax jumper to the 7300's antenna jack
T/R: This connects to the 7300's Amp-keying line.
Note: You MUST set TX-Delay in the software menu (page 12-1 in the basic instructions) to be longer than the switching time of the relay you use. If you are not sure, use 25 mS.
- The LED and R3 are optional, but provide an indication of when the RX antenna is activated.
- The Relay must be capable of switching 100 Watts of RF power. The Panasonic SDS DR-12V is a good choice. (Manufacturer DR-SDS-12). I you can't find one, use an equivilent (in switching voltage and power handling).
- The "Flyback" diodes D1 and D2 should preferably should preferably be a 1N4148. Diodes of the popular 1N400x series may also be used, but they have a longer release time delay than the 1N4148.