Rich,
Since I don't use CW breakin so I don't expect a problem in that mode. One
last question: lets say I take care of the delays on transmit. Is there a
potential problem going back to receive. Can an amplifier "ring" and
potentially cause an overload of the transceiver front end?
Len
At 02:30 AM 12/2/97 -0800, you wrote:
>>Rich,
>>
>>I am rapidly getting the feeling that I totally misunderstood what everybody
>>meant by "hot switching". I thought it meant that the transceiver was seeing
>>undesirable transients because it changed modes - ie receive to transmit -
>>before the amp could switch and present the proper load on the transceiver.
>>Now I'm getting the feeling that you are referring to opening and closing
>>SB220 relay contacts while they are carrying current.
>>
>>Could you help clear up what you mean by hot switching?
>>
>Hotswitching usually means that the transceiver begins delivering RF
>before the amplifier relay contacts have closed and stopped bouncing.
>The way to tell if this is the case is to watch the SWR indicator in the
>transceiver. If the SWR indication briefly spikes upward when the VOX
>trips, or the PTT button is pressed, hotswitching is indicated.
>A better test is to send CW dashes, watch the SWR indicator on the
>transceiver, and vary the speed.
>
>If RF is on the amplifier relay's contacts during contact-bouncing, rapid
>contact errosion takes place.
>
>Some modern radios begin producing RF in 5mS. If the amplifier relay can
>not beat 5mS, it will get beat up. The circuit shown in Figure 7B on my
>Web site will switch in 2mS or less. [circuit also in "The Nearly
>Perfect Amplifier", 1-94 *QST*]
>- - (note: a Jennings RJ-1A vacuum relay will not switch fast enough to
>beat modern radios unless it is driven with a v-limited {100v - 160v}
>current source instead of a fixed voltage {usu. 26v} source.)
>Rich...
>
>R. L. Measures, 805-386-3734, AG6K
>
>
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>
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