JUMA Amateur Radio Forum

Hi, Dave, First, antenna blanking. The Juma outputs a DC voltage on the antenna output when in the transmit mode. This voltage is used by the companion PA-100D linear amplifier as the transmit enable signal, and switches the amplifier from its bypass mode into its active transmit mode. The first sch...

For those following this post, after a number of email exchanges between myself and Bob, he discovered that the open-circuit DC voltage on the TX DATA line was only -8V rather than the -9V that it should be. He measured tha DC voltage on pin 16 of IC10 and found it was only about 4V, rather than the...

OK, glad we managed to sort out the problem. Happy to be of service. Would you like to try my firmware modifications? If so I'd be happy to send you the latest build and the User Manual. Send me an email to: adrian04@cytanet.com.cy There is also a new version for the PA-100D. If you have any questio...

Hi, Perhaps I can be of assistance. You would do well to print out the three schematics that relate to this, the ALL BAND 10W POWER AMPLIFIER CIRCUIT DIAGRAM, the RF FILTER BOARD BPF SECTION, and the RF FILTER BOARD LPF SECTION. How does all this work? In the receive mode RL1-A and RL1-B are de-ener...

There is now a later version of this firmware available, Build 4. This fixes a bug that was brought to my attention by Jan Wieck, thanks Jan! He spotted that when you set the CW keyer mode to Straight, and wire your straight key to a mono 3.5mm plug, then during the boot sequence you will hear conti...

Gentlemen, I can confirm that the Belkin F5U409 USB-Serial converter simply will not work. I have tried to use this convertor myself and have had lots of problems with it. The USB to RS232 convertor I use has an FTDI chip in it, and that works under Win-XP/Win-Vista/Win-7. For Vista and 7 you will n...

As a result of feedback from a number of interested amateurs, version 1.07y is now available. This is of particular interest to the US community, as this firmware now incorporates the ability to selecte either the Extra or the General Class licence band limits for the out-of-band detection. It also ...

Hi, Jan, I forgot to mention R26, which adjusts the gain and hence the output power on the SSB modes, my apologies. R28 sets the CW carrier level, of course. By adjusting these two potentiometers you can easiy set the transceiver up for no more than 5W in either CW or SSB modes. The fixed attenuator...

Since I cannot leave anything alone for very long, there is now an updated version of the firmware for this transceiver, version 1.07x. This introduces a slightly modified feature, an anomaly fix, (hardly a bug), and some general improvements in the operation. The enhancement allows you to adjust th...

Hi, The output power of the transceiver can be adjusted by means of the carrier level control R28 on the main board. It is normally set to give an output of 10W, but this can easily be reduce to 5W by re-adjusting this potentiometer if you wish. The output power can also be set with the on-board att...