JUMA Amateur Radio Forum

Good Morning, Paolo, OK, let's see if we can determine what is wrong here. You have already demonstrated that the PA-100D has a fault, and therefore you can now disconnect your KX3. The following tests will serve to verify the TX/RX logic is working. You will need to connect the amplifier to a dummy...

Hi, Paulo, If the RF signals from the antenna are being severely attenuated, this can happen if RL1 is energised when it should not be. This will disconnect the transceiver from the antenna, and instead connect it to the amplifier's input attenuator. RL1 should only be energised in the OPERATE state...

Hi, Some time ago I wrote a modified firmware for the Juma TRX-1 DSB/CW transceiver, and included in the package a User Manual. You can find the modified firmware for this transceiver on the web site, but I am attaching the User Manual for my firmware to this post to give you an idea of its capabili...

Please note - Build 10 has been removed, having been replaced by Version 3.0 Build 16. I would strongly recommend updating to this later version. This version of the firmware incorporates two new features - CW Annunciation, and a CW Practice Mode. Build 10 fixes a minor bug in the Serial Test Suite,...

OK, just a thought - have you ensured that your VFO button is working? I know it sounds obvious, but if for some reason your transceiver is not recognising the VFO button, then this would obviously cause a problem. If the VFO button is being recognised, then, yes, you will have to re-flash the micro...

Good Morning, Frank, The first thing is to check that your TRX-2 is actually executing the flash writer code. With nothing connected to the RS-232 port, from the power OFF state, press and hold the VFO button. Whilst holding the button, briefly press the PWR button to turn the transceiver on. You sh...

I have just finished assembling the new FL-2 roofing filter for the Juma TRX-2. I thought it would be interesting to compare the FL-1 and FL-2 frequency responses to show the improvement obtained with the new filter.

Attached is a PDF document showing the results.

73, Adrian, 5B4AIY

Whilst performing a code examination I noticed that when calculating the SWR there was a very remote possibility of provoking a Math Trap Error. If the reflection coefficient was ever exactly 1 then an infinite VSWR would be registered provoking the error. In the last 4 years I have never had either...

Whilst performing a code examination I noticed that when calculating the SWR there was a very remote possibility of provoking a Math Trap Error. If the reflection coefficient was ever exactly 1 then an infinite VSWR would be registered provoking the error. In the last 4 years I have never had either...

Good afternoon, Hubert, OK, you can easily verify if the flash writer is working. Do not connect anything to the serial port. From the power OFF state, press and hold the OPER button, then briefly press the PWR button. Note: As soon as the display backlighting illuminates, release both the PWR and O...