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My grandson and I are still stuck on step 1 "LCD contrast adjustment". We are following the current Trouble Shooting page under "Digital Section" and are getting the results as listed under"LCD all

RS are a nice motivational site I find. Usually you go there and after the instant pffff noise, tutting and shaking head for a bit it motivates you to find a cheaper distributor and part. My

Hi Chris, Karlis Yes! All agreed with Karlis! Chris: ?17 for a set of LM4562 from RS? Hi hi. I didn't say I got a good deal from RS specifically hi hi. Yes Karlis is correct, the first stage has 40dB

Even IC5 is AF, but it sees a very quaint signal, so noise voltage and noise figure is paramount there. IC5 gives about 40 dB of gain, after which the total receiver noise figure (or sensitivity)

Thanks for the info Hans - appreciated. That helps a lot with this idea. Karlis YL3JG thanks also! The LM4562 is a rather good across the board looking at the datasheet. Especially if you got a good

Hi Chris Nice job. Yes I was just about to say what Karlis said. I use LM4562 everywhere, even though only the first state (IC5) needs such a high performance low-noise op-amp. I do that because: 1)

I would say if you want to really save power, replace the hungry LM4562s where it makes sense, i.e. all of them except for the first stage, IC5. It's a nice low noise part, but each of those suckers

Hi, I was somewhat inspired by Kent W9WB's switching regulator mod and decided to have a bash at this myself. I looked around for regulators that had documented frequency. Turns out Recom's R-78E-0.5

Carl, If replacing the Si5351 is going to solve your problem, as you're only about 25 miles away, either ship it (with a new Si5351A) or bring it over and we'll replace the chip. Please contact me off

Not only that, if you screw it up you have nothing to lose if the unit doesn't work now anyway :) I will detail my MCP1700 regulator mod when I get some time next week. Chris M0XTE

Carl M0ICR Replacing the Si5351a is not all that difficult. I would use a Dremel type tool to cut the legs from the original chip. Then use a soldering iron and wooden toothpicks to remove the leg

Thank you to everyone for your useful tips and advice. After further testing I am now sure that the Si5351A is kaput, I am also sure that removal and replacement is beyond both my tools and ability. I

Thanks very much for your replies. It was my very first post so I wasn't sure what to expect. Now I know it works. I will repost my original and see if it goes through. Maybe I didn't hit the send

The Si5351 is apparently a little fragile, they die if you overload the outputs apparently...

That sounds like the Si5351 is dead or heavily loaded. It's worth checking what it is connected to first before replacement. If it is drawing lots of current that might be because one of the IO /

Carl, Continuing with guesswork it seems that when Q6 failed it sent 12V through one of the BS170s (that had also shorted) to IC3. This then seems to have somehow sent the 12V through to the the

A quick check of other components running very very hot include the Si5351 (oh dear!) and the D1 and D2. 73 Carl M0ICR

I would thoroughly visually inspect all parts and solder joints top and bottom if this has transitioned from working to non working. Worth checking the input current to the 7805 and output voltage of

Do you have access to a thermal imaging camera ? If you cant borrow one, or justify ?100+ to buy, build your own

So ... I have removed IC3, Q1, Q2, Q3, Q5 and Q6 and the 7805 regulator is still getting too hot to touch. Any thoughts please? 73 Carl M0ICR