My 1208 transverter blew pin diodes D5 and D6 when I accidentally
transmitted 100 wats from my old Paragon. I replaced the diodes with 1N4148
which are standard diodes. I have accidentally done this again a few times
over the years and no further problem has ever occurred with the 1N4148's in
there.
My N4PY software using its full transverter features, prevent this from ever
happening accidentally.
Carl Moreschi N4PY
121 Little Bell Drive
Bell Mountain
Hays, NC 28635
----- Original Message -----
From: "Dr. Gerald N. Johnson" <geraldj@storm.weather.net>
To: <tentec@contesting.com>
Sent: Tuesday, January 13, 2009 11:54 AM
Subject: Re: [TenTec] 1208 Transverter
> On Mon, 2009-01-12 at 22:42 -0600, Bob McGraw - K4TAX wrote:
>> Easy solution, build a 50 ohm 10 dB pad or attenuator and use it between
>> the
>> transmitter output and the transverter TX input. For the input resistor
>> use
>> 10 pieces of 2W carbon 1000 ohm resistors connected parallel, the output
>> R
>> should be 100 ohms 2 watt and the series resistor of about 75 ohms. This
>> will make a pi pad design.
>
> With 2 watt carbon resistors being hard to buy, and having a pronounced
> tendency to drift in value from heat, I'd prefer the 3 watt tin oxide
> film type resistor. I've tested them to ten times rated power without
> permanent damage or shift in resistance. Though they did tend to ignite
> their environment from the radiated heat. True the resistive film has a
> spiral cut in it. I've been unable to detect (measuring at 144 MHz) more
> inductance than that of a rod the size of the resistor.
>>
>> You will need to bring the IF output separate from the transverter to the
>> AUX RX input on the Corsair.
>>
>> As to the input of the transverter hit with excessive power, yep, you get
>> one shot to blow the input mixer.
>
> The mixer is fairly tough and since it needs less than a milliwatt of RF
> drive there is a lot more attenuation on the transverter board, at least
> 30 dB, maybe as much as 37 dB, which knocks 100 watts down to 20
> milliwatts at the mixer.
>>
>> 73
>> Bob, K4TAX
>>
> 73, Jerry, K0CQ
>
>
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