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Old 16-09-2008, 18:22   #1
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SSB Antenna Tuner

Hi Ham radio experts.
My Codan 9390 SSB radio will not transmit on Hi power, only about 70W output on Hi, should be 125W.
Appears repairs are almost as expensive as replacement.
Has anybody an idea of what (inexpensive) SSB to buy?
I'm heading to Singapore.
Also need to know if I could use my Codan auto tuner on a different brand of radio.
Thanks for your help.
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Old 16-09-2008, 19:21   #2
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How are you testing the output? SSB radios are generally rated in Peak Envelope Power (PEP), which is considerably higher than the CW output. For example, many radios with a 100 or 125W PEP rating will only put out about 70 watts CW.

I would not assume there's something wrong with your radio. Have it checked out by a competent radio guy.

"Inexpensive SSB"?? You're joking, right? New ones run over $1,000. Least expensive one...and a good value...is the Icom M700Pro.

Bill
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Old 16-09-2008, 21:00   #3
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Thank you, Bill

I am in Malaysia. The output was checked by a Malay "Radio Tech", with some faily facy looking equipment.
He is telling me that the power amplifier module needs to be replaced.
If I need to replace the radio, would I need to purchase a new auto tuner as well?
He is telling me that the tuner is OK.

Thanks again, Bill
Have a great day,
Walter
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Old 17-09-2008, 05:50   #4
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Walter,

Selamat pagi!

I'd be suspicious of the diagnosis of a bad power amplifier if, indeed, you are seeing 70 watts out. The oscillator stage only puts out a few watts at best; the power amplifier transistors kick that up to whatever the designed power level is.

In Malaysia, you should be able to find a good power/swr meter. Make the investment (about $90-100 for a good one, like a Daiwa). The current model Daiwa which would do you well is the CN-101L...it sells for about $100 here in the States.

A power/swr meter should be standard equipment for ANY HF installation, IMHO, just as it is for ham stations. It will tell you at a glance if your transmitter and antenna system are performing correctly. You insert it close to the transmitter, using a short pigtail of RG-8X coax with a PL-259 connector on each end.

Again, a 125watt PEP class transmitter will show less than 100W on CW transmit. This is normal. But, whistling into the mic, you should see the meter kick up to somewhere near the 125-watt level, PROVIDING that:

1. you have ample size wiring to the transceiver (AWG6 at least for runs of more than just a few feet); , HF radios should be wired directly to the batteries -- with appropriate fuses -- not thru a panel or sharing connections with other equipment.

2. your connections are clean and tight;

3. your batteries are up; these radios are designed for 13.6-13.8V input, which is considerably more than a storage battery will have unless a charging source is connected; their voltage tolerance is +/- 10-15%; and

4. your antenna system (coax to the tuner, tuner to the antenna, RF ground system) is functioning properly: clean, tight connections everywhere.

Then, and only then, can you properly diagnose what's going on with your radio.

By the way, the difference between 70W and 125W output is less than 3db...barely discernable at the listening end :-)

Good luck and selamat djalan.

Sorry, I won't be around for a few weeks most likely...going sailing!!!

Bill
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Old 04-10-2008, 05:23   #5
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Hi Bill
Happy to say you were right.
I checked the radio & tuner again after reading your mail & found that what I thought was some minute rust on the tuners earth connector was major.

Nothing wrong with the power amp, as the technician was trying to tell me.

Radio working fine now.

Thanks again, happy sailing,
Walter
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Old 04-10-2008, 06:42   #6
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Happy to hear it.

Good sailing!

Bill
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