Re: TS-690S transmits on 6m but not on HF
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Bob, ? As an example, page 137 of my PDF copy of the service manual has several test points with two voltages shown. The second voltage is in parentheses. ? 73, Stan N6BYU ?
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From: [email protected] <[email protected]> On Behalf Of Bob
Sent: Monday, February 26, 2024 2:49 PM
To: [email protected]
Subject: Re: [Kenwood-Amateur-Radio] TS-690S transmits on 6m but not on HF ? I looked?at the PDF. I cannot find a "legend" that states what the voltages mean. Some voltages are in parenthesis???? It does say "tx" on some of them.Maybe Jordan can tell from his regular service manual. ? I'll have to break out my actual service manual rather than rely on the pdf version. I'm sure there is a legend somewhere but it's?very time consuming?to find in the pdf. I'm tempted to say those voltages are in Rx and then Tx but I'm not 100% certain of that...Maybe someone else knows, but in the meantime I'll pull my SM copy and check when I get a chance... ----- Original Message ----- Sent: Sunday, February 25, 2024 9:37 PM Subject: Re: [Kenwood-Amateur-Radio] TS-690S transmits on 6m but not on HF Jordan, ? I’m just now getting used to the layout of the service manual, so your pointers have saved me a lot of time and frustration. ? Any idea what the voltages in parentheses represent? I’m sure there’s some sort of explanation somewhere in the manual, but I haven’t found that yet, either! ? I’ll report back what my measurements show. ? 73, Stan N6BYU ? ? According to Item 2 of the TX Adjustment on pg. 124, you should measure ~10dBm minimum at CN-9 on the RF board. You should be able to connect your SA through a DC block?across the output of the cable connected to CN-9, or connected across the?other end of the CN-9 cable?itself. Personally, I use a section of .141 rigid cable with?an SMA female connector on one end, then I can connect my RF millivoltmeter or when necessary, my SA. Page 163 shows RX and TX stage AF and RF levels as well... ----- Original Message ----- Sent: Sunday, February 25, 2024 3:24 PM Subject: Re: [Kenwood-Amateur-Radio] TS-690S transmits on 6m but not on HF Using my spectrum analyzer, I placed an RF sniffer probe near the output connector of the of the HF amp board. I saw activity at the proper frequency, but at a very reduced level as compared to what I saw when transmitting on the 6 meter band with the probe near the 50 MHz output coax.
I've looked at the HF amplifier schematic in the service manual, and it shows what I assume are DC voltages at various points around the board. Some points show only a single voltage, and other points show a second voltage in parentheses. I assume that the first voltage is measured in the receive mode, and the second voltage (if present) is measured in the transmit mode.
I don't see any references to what HF levels I should see at the various points in the signal chain.
I'm thinking that the low output is due to either a failed transistor (or transistors), a problem with the level of the RF input to the board, or a poor connection at one of the connectors, but without knowing what the expected RF levels at the test points are, I would just be guessing.
Any help on how to proceed from here is appreciated!
73,
Stan N6BYU
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