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Author Topic: Auto Tuners  (Read 478 times)
WX7K
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Posts: 45




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« on: November 26, 2008, 05:15:34 PM »

When using one of the digital modes that scan different bands and requires an acknowlegement (i.e. pactor), it seems that you would need a tuner that would sense RF and go into a tuning cycle for the band on which the signal is received. Is this a correct assumption? I know SDG hs this feature. What other tuners have this feature available? Reading the manuals for some tuners I note that some advise reducing power to 10 watts and most "auto" tuners require a button be pushed to enter the tuning cycle. Any help or insight would be greatly appreciated.
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NA0AA
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Posts: 1042




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« Reply #1 on: November 26, 2008, 09:51:04 PM »

When you use WinLink you need a tuner that can handle the ALE type operation, but then your receiver needs diode switching as well.

SGC couplers have that option, you have to open 'em up and set the DIP switches as required.

You did mean WinLink right?
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AA4PB
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Posts: 12841




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« Reply #2 on: November 27, 2008, 02:55:54 PM »

Actually it would be preferable to use a broad band or multi band trapped antenna for such digital scanning operation. There are two reasons for this. One is that the tuner will be left setting on the last band that you transmitted on so it could result in some loss when listening on bands for which it is not tuned. The other depends on the radio and tuner type but basically it will go into tune mode while you are trying to establish the link which will delay the establishment of the link.

Icom radios have a function called PTT-tune where they will put the Icom AH-4 tuner and radio into tune mode each time the radio is keyed on a new frequency (or one more than 1% removed from the last frequency used). It also puts the tuner in bypass each time the band is changed (until you transmit) and that helps the receive function because a bypassed tuner often has less receive loss than one tuned to the wrong band. If the frequency is already in tuner memory then the low-power tune operation can occur in a couple of seconds or less. Otherwise it may take 10-15 seconds to find a match and begin answering the call.
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AA4PB
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Posts: 12841




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« Reply #3 on: November 27, 2008, 02:59:28 PM »

SGC tuners have an option via internal DIP switches to always have the tuner in bypass during receive. The tuner then only affects the transmit signal. It is accomplished via the relays so they will be switching with every send/receive cycle.

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