OZ5RM 's Report on the Index QRP Plus

...Thought you might be interested in hearing about my preliminary impressions of the Index QRP+ in its NEW VERSION (mine is dated June 04) which was returned to me from the Index Labs with new innards... at a price of $250 + $70 APS freight. Into the bargain, I had to pay our VAT plus a "COD" charge, another $90.

That's a stiff price. Was it really worth it? Well, let's look at the 'old' Index first. Mine was No. 504 and was fitted with an updated chip some time later.

Last year, the Berlin QRP Gang suggested some mods, and I had already modi- fied the RX in accordance with their instructions - without too much success - before deciding to return it to the factory. My particular Index suffered from the following serious drawbacks:

1) The combined phase noise and intermod products were so bad that a strong, unwanted signal already at a separation of 112kHz created an output 3dB above the minimum detected signal level. (For a good amateur RX this figure should be somewhere between 5 and 15kHz).

2) Several spurs could be heard across all bands. At the "OZ Magazine" Lab they were found a approximately every 7kHz point.

3) The TX, in my case, did not sound quite stable on CW. Break-in was non-existant. The TX/RX turn-around time was about 1.5secs. On SSB, the modulation was horrendous and weak, partly due to a poor bias regulation in the PA. (I did not perform the 5V regulator installation recommended by the Berlin QRP Club. By all means, try this one!)

4) My Index produced much stronger TX harmonics/spurious sigs than a 100 W Icom 765 transceiver as evidenced on a TV set in my /A QTH where TV-sigs are pretty weak.

5) The RX AVC created some VERY unplesant pops when a strong signal appeared on the operating frequency. Electrical noise such as that from household appliances had a similar effect, not to speak of distant thunderstorms. The RX was frequently knocked dead for a few secs.

Now, several hundred bucks later, the situation is quite different.

A) Although no measurements have been made, it is quite evident that the RX works MUCH better. SSB sigs sound almost like those on my big rig. There are still some intermod products when I operate close to a very strong signal, but not much.

B) The numnber of spurs on the RX has definitely been reduced.

C) The CW sigs sound quite nice, a bit hard - but 'clean'. The AVC, which seems to be working partly on an IF-basis, is good now. Index say that they have even introduced some kind of noise-limiting in the IF; this may be true - it is no longer as sensitive to QRN as it was. Break-in is possible up to at least 30WPM, even with an external keyer. (Previously, even when using the internal keyer, QSK disappeared at around 22WPM). The built-in keyer has a speed range of 10 to 45WPM in 1WPM steps (like in the updated chip supplied recently). The modulation on SSB is quite good and fully sufficient. This must be due to the socalled VOGAD system now used (constant mod level; no pot to adjust now). Also, the PA stage has its bias stabilized with a 7805. I have received a few reports on a slight frequency drift, though. This may be due to the VFO knob's unevenly distributed weight: it is known to have a tendency to turn a bit by itself when placed in certain positions.

D) The only serious harmonics I have found till now - by listening on another RX - is the second harm, i.e. transmitting on 3.550kHz produces an unwanted signal approx 35dB down on 7.100 kHz. Nothing has been found higher up. The PA filters do not seem to have been changed, so the improvement must be due to the aforementioned bias regulation. A good antenna tuner (not one with a T-filter) is still a very good idea.

E) The AVC is MUCH better and does not produce clicks. The turn-around time is quite short now. HOWEVER: When I ran my Index from a 12V battery, the CW-tone deteriorated somewhat, and the turn-around time was back to about 1.5sec! Use a well-regulated PSU of at least 13V!

F) A few words on the subject of the MICROPHONE. It is mandatory that you study the new manual and wire the mike accordingly. I had to do this with the little Icom HM-65 even though the manual says that it should not be necessary to modify it. I also rigged up a simple electret capsule with a switch in series (PTT) without any sort of resistors or caps and it seemed to work just as well.

Boy, had I only waited to buy my Index till the new version was on the market!

Comments are invited.


(I found the above report on packet and hope it is of interest to you - G3YCC)

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