Possible mistake in TRX2 Main Board voltage table

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Possible mistake in TRX2 Main Board voltage table

Postby WI3CK » 23 Mar 2012 22:57

Hello,

after many months not being able to work on it, I finally finished my TRX2A. This is my first HF radio. A little trouble with the forum sign up (thanks for fixing that Matti) actually gave me time to double check all the Filter and Main Board voltages and (of course) find the two OP-AMPs that I had soldered in wrong as well as a bad contact at another IC.

All of the voltages now check out. A few are within +/- 10%. Considering that I was picking up CW and SSB stations in Florida, Texas and Tennessee (and a radio station in Beijing) from Pennsylvania last night with a 10m long wire strung across the living and dining rooms, I think the receiver part is doing OK. A pair of 2.5m long wires used as a crude dipole hammered a signal into my Handheld on the 10m band, so it seems the transmitter works as well.

The only voltage, that doesn't agree with the Main Board voltage table, is pin 15 of IC2 in CW transmit mode. It reads 0V instead of 5V. However, if I read the schematics correct, the pin is connected pin 6 of IC4, which should and does read 0V in CW transmit mode. Am I correct or do I have a problem?


Regards,
Jan WI3CK
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Re: Possible mistake in TRX2 Main Board voltage table

Postby OH7SV » 24 Mar 2012 15:50

Jan,

You are right, IC2 pin 15 should be zero in CW during transmit state. This is not a mistake because all the voltages in the "Main Board DC voltage table" are in Receive state, Mode LSB. The IC2 pin 15 selects the TX muxer to CW during transmit.

Main Board DC voltage table www.jumaradio.com/juma-trx2/rev-b/main- ... -table.pdf

So no problem with that Jan.
Enjoy QSOs with your JUMA TRX2.

73 Matti OH7SV
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Re: Possible mistake in TRX2 Main Board voltage table

Postby WI3CK » 24 Mar 2012 22:35

Thanks for confirming that.

IC2 is actually listed 3 times in that table. I was referring to the second to last line under

"Conditions: Transmit state, Mode CW, f = 3.7 MHz, Filter WID, AGC slow, Speechproc OFF, NB OFF, MIC input, dummy load"

Regards,
Jan WI3CK
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Re: Possible mistake in TRX2 Main Board voltage table

Postby OH7SV » 25 Mar 2012 07:54

Oh yes,
It seems there is a mistake during CW transmit state.
I will correct that.

73 Matti OH7SV
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