Should contest rules allow and act upon 599K QRM reports?

Saturday, 7 June 2014

President Lincoln II V3 cw testing (part 3) more findings

Testing with a second transceiver, I realised that the President Lincoln II V3 cw mode is DSB (Double SideBand), reminisant of the old tentec centuary 22 transceiver and the like. This means I can hear my second transceiver tx twice whilst tuning on rx with the Lincoln (-600Hz -> null -> +600Hz, as my menu item "CWtoFr" is set to "600" meaning that my tx/rx cw tone is 600Hz offset from my centre frequency). This is similar to some of the simple cw rx kits I have built in the past which do not supress the rx'd opposite sideband in an attempt to keep things simple and cheap. The trick to using these simple receivers is to decide which rx sideband to tune for and stick to that. With the Lincoln, I've decided to always tune through the LF rx image to the HF rx image of incoming cw stations (clarifier centered and with split engaged (-600Hz offset)). This means I can go straight back to them and they will hear me. If the HF side has interference from another rx station then you can alternatively tune for the LF side provided you change the split to +600Hz offset. Using the split function simply means that the tx frequency of the Lincoln is different to the rx frequency by an offset frequency amount and direction (up or dwn). Using the split feature avoids the "tone drift" firmware problem (described in an earlier post) caused by using the clarifier. Unfortunately this means that the frequency display will read +/-600Hz out. I'm learning all the time here and am pretty disappointed with "the best" cb offering for cw mode. The DSB receiver is a hardware design and cannot be fixed in firmware. The slow CW to PTT time may be improved in firmware, but will be limited by hardware. The erroneous tx "long dah" problem (described previously) can be fixed in firmware. The initial tx cw element "tone shift" through using the clarifier is a hardware problem and cannot be fixed in firmware. Rating the cw problems with the President Lincoln II Mk3 (most important first) I'd say: 1) CW to PTT too slow. 2) "tone drift". 3) "long dah". 4) DSB rx. There are a lot of tx firmware bugs and the DSB rx is simply too crude a design for a transceiver of this price. Has any CB ever been properly rated for CW capabilities? Has President ever spoken to a CW operator before putting CW on the mode switch?. Does President realise the size of the 10m CW user base? CW Buyer beware, it kinda works but it's a lot of hard work for the price at this revision. This video link shows how to work a cw station on the President Lincoln II whilst avoiding the "tone drift" problem described previously:

1 comment:

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