Help needed with Index Laboratories' QRP+ radio

I need your help! 

But first some background. The Index Laboratories' QRP+ is a 1990's 5W all-band QRP transceiver from the USA. I bought mine at a club sale and it was supposed to be working fine.

But it wasn't! Never mind, we all love a

challenge, don't we?

It seems that the SBL-1 mixer is a common failure point so a replacement was ordered.

The rig comprises four boards, which are stacked and have interconnecting leads.

It is relatively easy to pull apart, and the mixer is on the top board.

After a big desoldering struggle I fitted the new SBL-1 (U5), which brought the receiver back to life. Unfortunately, the TX still didn't work. Back to the drawing board.

The next stage was to replace the final PA transistor, which is on the lowest board. This is a IRF510 (Q9) and I ordered a few off Ebay. I fitted a new one and in tests I found that I could only get about 0.1W out! (on CW) with the gate bias backed off fully anticlockwise. 

Power out should be about 5W.

Anyway, that's as far as I have got. I have attached a link to the circuit diagram and would appreciate any suggestions.

Update

Well, some replacement IRF510s were sourced from the G-QRP club (thanks guys). Apparently, there are some "fake" IRF510s around that don't play well with RF.  After pulling the radio apart (again) and replacing the transistor, it was a little better - about half a Watt output. Anyway, to cut a long story short I have passed the radio to another G-QRP club member and I hope he has more luck than I did! 

Update to UK propagation charts

I'll freely admit that my UK propagation charts had been a bit neglected over the past year. But not any more!

I've now updated them until the end of 2024 with new predicted smoothed sunspot numbers.

I've also fixed a problem with the Kp graphs. They now appear, along with solar X-ray and proton flux graphs. This was because the US Space Weather Prediction Center had stopped the production of the previous Kp chart.

I still recommend both Proppy and VOACAP.com if you want detailed HF forecasts, or if you want to do long-path predictions. But for casual use my charts are fine, and produced using VOACAP.

Leave a comment if you find them useful (or not!).

Incidentally, the SSN charts I used show that the expected solar maximum is the middle of this year.

Preparing the GB2RS propagation report

Attached below is a PDF (14Mb) of the presentation I gave on 15th April 2023 after the RSGB AGM.

It looks at how we prepare the weekly propagation report for the RSGB's GB2RS news report. It contains a lot of useful URLs to sources, data and programs that people might find useful.

Steve G0KYA

Download GB2RS_Propagation.pdf

Ten metres (28MHz) beacon list updated

I've just spent two days updating the RSGB's 28MHz beacon list. I used the reverse beacon network and logged/updated the beacon list accordingly. This takes a lot of time as many of the "spots" are misread and have to be checked individually.

Beacons heard over the last three years are highlighted in red. I'm now happy that it is pretty up-to-date. The RBN has a beacon listing, but it is way out of date - GB3RAL is still listed and that hasn't been on for years.

I think this is the best way as it reflects beacons that are actually transmitting and not just listed. The full beacon list can be found on the propagation section of the RSGB website here: https://rsgb.org/main/files/2024/10/RSGBs-Worldwide-List-of-HF-Beacons.pdf

Change of freq/details:

28270.5 PY4MAB  Pocos de CaldasGG68      2W    

28193.1 LU2DT   Mar del Plata  GF12      5W 

28208   WD5GLO  Minco OK       EM15ah    3W 

28281   AG8Y    Middletown OH  EM79TL  7.5W   

28273.8 WI4L    Dalton GA      EM74MS                    

28243   AA1SU   VT             FN34KL    5W   

28209.5 N2UHC   St Paul KS     EM27JM    4W

28203.3 WB9OTX                 EN55      5W             

28280.4 KE4IFI  Lexington SC   EM9JV     7W 

Additions:

28297.9 K4JDR   Raleigh, NC    FM05     10W 

28255.8 WB4NCT  Athens, AL     EM64      5W  

28241.3 WW2BSA  Warren, NJ     FN20OU    7W   

28260.8 IQ8BB   Salerno        JN70JQ      

28178   IQ0GV   Sora           JN61TR    5W    

28236.3 F1ZTS   Rochefort      in97QI   10W     

28266.1 VK4RST  St George QLD  QG41HW   10W

28285.9 AJ4YN   Chesapeake, VA FM16UO    ? ?   

28215   GB3MCB  Cornwall, UK   IO70OJ    ? 

28252.6 WD8INF  Lebanon OH     EM79VK   10W

28258.8 AC5JM   Bartlesville OKEM16FT    ?

28209   N5TIT   Westminster, COEM12PX   10W 

28206.5 N4SO    Grand Bay, AL  EM50tk    6W   

28296.2 VE3IIM  Hanover, ON    EN94LD    4W 

28321.4 IZ1KXQ  La Spezia      JN44WC  0.1W

28230.8 NG7I    Ritzville WA   DN07TC    5W  

28202   WB7EUX  Joseph, OR     DN15JI   10W 

28233.5 K7RA    Seattle, WA    CN87UQ   11W  

28260   KC4QLP  Little Falls NYFN23OB   10W  

28245.3 K0WKT   Black Dia. WA  EN36WT    5W 

28226   K6KWS   Redwood City CA CM87VL  10W 

28240.1 W8EDU   Cleveland, OH  EN91EM   10W

28206.9 N4XRO   Burbank CA     DM04UE    5W 

28276   XE1JAL  Xalapa         EK19MM    5W

28230.3 W2MQO   Grand Island FLEL98dv   10W

73 de Steve G0KYA
Chairman, RSGB Propagation Studies Committee

Autumn 2022 HF popagation charts updated

 

I have just updated my propagation charts for October, November and December 2022 with new sunspot numbers. 

I will update the Spring 2023 charts when we get a little closer as they are likely to change as we head towards the maximum of solar cycle 25. 

Anyway, it is nice to see some good predictions of DX on 10 metres and if the past two weeks are anything to go by they are pretty spot on with very loud signals from the USA. 

ARRL's W1AW's CW practice files were romping in the other day on 28.0675MHz Nice to see 10 metres doing what it does best! 

Click here for the charts or use the link on the right-hand side.

Repairing a MFJ-1786 magnetic loop

I just wired up my MFJ-1786 magnetic loop, which hasn't been used for years. Unfortunately, it looked like the loop controller had gone U/S. 

The meter lit up, but pressing the loop buttons had virtually no effect. The amber lights flicked slightly, but they were not so bright as I remember them, and the motor didn't turn. I got hold of a schematic, but it is way more complex than I thought it would be. I first changed the only electrolytic capacitor in the unit as it was getting quite old, but it made no difference. 

I then stripped the antenna and made sure it was all OK. Connecting a 9V battery made the motor turn, so I sprayed the motor with grease and put it all back together. Turning to the controller again I first changed Q1, but that made no difference. Then I changed Q5, but nope! So I moved on to the U5 78L12 voltage regulator, which is fiddly job as it is an 8pin SMD. 

And low and behold it works! I just need to fix the power meter, which displays reflected power, but not forward, but that can wait until another day. Then finally I can mount it outside for final testing. I've attached the MFJ-1786 schematic as this was quite hard to track down - might come in handy for someone in the future.  Click on the image above to see a larger version.

Update

Well, it wasn't a diode that was stopping the meter from working, just a poor connection. 

So I now have some spare diodes for the future! I've uploaded a higher resolution version of the schematic too.

Steve G0KYA

HF propagation charts updated for 2021

I've now updated my propagation prediction charts for 2021 with the predicted smoothed sunspot numbers from NOAA/NASA.

So that's a chart for every hour, for every band and for every month, or more than 2,300 charts in total! The process is fairly automated, but it still fairly tedious and takes about a day to do.

The charts are useful as a quick guide to what parts of the world may be workable and which aren't. If you want more accurate charts then the ITURHFPROP-based predtest.uk or the VOACAP-based voacap.com websites are better.

I may need to update them as the year progresses as we get a better idea of how Solar Cycle 25 pans out. At the moment it isn't looking too good. December 2020 saw a sprinkling of SS25 sunspots with a corresponding rise in HF activity. But since January is has been pretty dire really with long periods of no spots 

Anyway, to avoid confusion, I have updated form February onwards. This means that January is actually for 2022. 

The charts are produced using Hamcap which is a VOACAP-based application and they are for short-path only.