80m on Classic Bands Board: Very Low or No Output

Post Reply
ae4na
 

Posts: 4
Joined: 04 Jun 2022, 19:16

80m on Classic Bands Board: Very Low or No Output

Post by ae4na »

Hi, I've recently built out the classic bands board, and I have little or no output on 80m. The radio receives on all bands, and transmits at ~4w on everything but 80m. Occasionally, I'll see it transmit at 1w, which quickly drops to 0w. I've rewound and replaced both toroids, with no effect. I hear the relays click when I change to 80m, and as I said, I can receive on 80m. The solder joints are good, and I scraped and sanded the enameled wire before soldering the toroids. Is it possible I have a bad cap or relay?

Edit: Ok, now looking at it, what I was hearing on 80m that I thought was receiving, may actually just be birdies from the radio itself.
KM6HHP
 

Posts: 3
Joined: 25 Dec 2022, 03:47

Re: 80m on Classic Bands Board: Very Low or No Output

Post by KM6HHP »

I have the exact same problem but on 40m.
What do I check? Where should i look for the problem?

-receives ok on all bands
-relays clicks when changing bands.
-20, 30, 60, 80m get 3-6w output on 13.8v no problem.
-40m only puts out .01-.04w output. SWR is always high 2-5 on tx.

thanks
KM6HHP
 

Posts: 3
Joined: 25 Dec 2022, 03:47

Re: 80m on Classic Bands Board: Very Low or No Output

Post by KM6HHP »

I just wanted to mention i fixed my low .02w TX output only on 40m by hitting a few solder points over again on the rf board. It seems that even though some random solder point looked good, it wasn't.

I thought it was a blown BS170 at first, and swapped one out with a BS170-075 from digikey. That did not fix the issue. The issue was a cold or bad solder somewhere else on the rf board.

Check your solder points if one band has low TX power! All Radio TX works great now.
ae4na
 

Posts: 4
Joined: 04 Jun 2022, 19:16

Re: 80m on Classic Bands Board: Very Low or No Output

Post by ae4na »

I think I may have found at least part of the issue. It looks like the classical bands board I received differs on the capacitor placement from the schematic provided by @dl2man. The classic bands board should have C51, C55, and C59 unpopulated, according to the diagram. On my board, C50, C55, and C58 are unpopulated. This doesn't seem to correspond to any of the three schematics provided. I bought the kit from Sunny's store on AliExpress. @dl2man, if you read this, can I simply replace the 0805 caps on the 80m section with standard values from a cap kit, or do they need to be a special voltage or tolerance?
dl6sez
 

Posts: 399
Joined: 30 Dec 2021, 22:54

Re: 80m on Classic Bands Board: Very Low or No Output

Post by dl6sez »

Hello OM,

have a look at the schematics, there is a paralleled place for every C in the lpf.
So it is equal if one takes C50 or C51, also for all other Capacitors C52/C53, C54/C55 and so on.
So what Sunny did is okay from this point. Also Sunny for example could have used one C instead of 2 Cs e.g. 2x1nF replaced by 1x2nF.....
But you are right there could be an error made, everybody does it wrong sometimes.
So the easiest way for you would be check it with a VNA like a nano VNA or something equal.
Have a look for the videos of Manuel showing how to align the lpfs.
Another tip for you: You can easily measure the Cs with a Multimeter (C measurement capable) in the circuit if you open on the toroid Ls one solder connection on each.
This works good for 80m but on 10m the Cs are too small to measure good with this method....
and NO you have to use NP0/CG0 100V capable Cs for replacement!

73 de Chris
Chris DL6SEZ, JN48XL near Ulm, Southern Germany
ae4na
 

Posts: 4
Joined: 04 Jun 2022, 19:16

Re: 80m on Classic Bands Board: Very Low or No Output

Post by ae4na »

Thanks for the explanation. I tried replacing the caps, but it had no effect. I can be happy with the board as-is, as I wouldn't use 80m from the radio much, if at all. If it really bothers me, I'll get an new RF board and go from there.
dl6sez
 

Posts: 399
Joined: 30 Dec 2021, 22:54

Re: 80m on Classic Bands Board: Very Low or No Output

Post by dl6sez »

Hello OM,

eventually you have a bad relay in the 80m circuit.... never heard about but never say never....

73 de Chris
Chris DL6SEZ, JN48XL near Ulm, Southern Germany
ae4na
 

Posts: 4
Joined: 04 Jun 2022, 19:16

Re: 80m on Classic Bands Board: Very Low or No Output

Post by ae4na »

I just got 10 relays in today from AliExpress. It was a bad relay on the 80m circuit. Thanks!
Post Reply

Users browsing this forum: No registered users and 6 guests