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I have used the two diodes back-back on a few receivers in the past. A friend of mine brought me a dead shortwave receiver one time. I had no problem finding the problem as the frontend FET was split into two pieces. He said that when he disconnected the coax he drew a spark off the cable. For that RX I installed a series capacitor as well as the diodes. He never had another problem. BTW his problem was with static on a really loooooong antenna.

As for sheer frontend overload from a commercial station, it does happen. If I was listening to the 10 Kw AM station I had to service when I drove into the TX site the audio would become a bit distorted and the 920 KHz signal could be heard over half of the band and nothing was heard on the other half.

On the FM band, if I was listening to the 100Kw signal, my car radio would go dead as I drove into the FM site when I was about 6-700 feet away and then come back again if I parked right at the base of the tower. The base of the tower was in a deep signal null. Both cases of overload have nothing to do with regulations or purity of the TX'ed signal and have everything to do with the RX's ability to handle strong signals.

The only time I have heard of a ham RX being blown out by too much RF on the front end was when my former boss forgot he still had his Kenwood R-1000 connected to the three tower AM array when he flipped the 1 Kw transmitter back on. No amount of protection was going to help in that case. He didn't fair too badley in the end, just a blown bandpass filter coil, a capacitor and the RF amp transistor. Not bad for about 225 VOLTS of pure and direct RF injection.

<blockquote data-quote="Captain Kilowatt" data-source="post: 226056" data-attributes="member: 39">I have used the two diodes back-back on a few receivers in the past. A friend of mine brought me a dead shortwave receiver one time. I had no problem finding the problem as the frontend FET was split into two pieces. He said that when he disconnected the coax he drew a spark off the cable. <img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f633.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":oops:" title="Oops!&nbsp; &nbsp; :oops:"&nbsp; data-smilie="10"data-shortname=":oops:" />&nbsp; For that RX I installed a series capacitor as well as the diodes. He never had another problem. BTW his problem was with static on a really loooooong antenna.As for sheer frontend overload from a commercial station, it does happen. If I was listening to the 10 Kw AM station I had to service when I drove into the TX site the audio would become a bit distorted and the 920 KHz signal could be heard over half of the band and nothing was heard on the other half. On the FM band, if I was listening to the 100Kw signal, my car radio would go dead as I drove into the FM site when I was about 6-700 feet away and then come back again if I parked right at the base of the tower. The base of the tower was in a deep signal null. Both cases of overload have nothing to do with regulations or purity of the TX&#039;ed signal and have everything to do with the RX&#039;s ability to handle strong signals.The only time I have heard of a ham RX being blown out by too much RF on the front end was when my former boss forgot he still had his Kenwood R-1000 connected to the three tower AM array when he flipped the 1 Kw transmitter back on. <img src="https://cdn.jsdelivr.net/joypixels/assets/8.0/png/unicode/64/1f622.png" class="smilie smilie--emoji" loading="lazy" width="64" height="64" alt=":crying:" title="Crying&nbsp; &nbsp; :crying:"&nbsp; data-smilie="17"data-shortname=":crying:" /> No amount of protection was going to help in that case. He didn&#039;t fair too badley in the end, just a blown bandpass filter coil, a capacitor and the RF amp transistor. Not bad for about 225 VOLTS of pure and direct RF injection.</blockquote>

[QUOTE="Captain Kilowatt, post: 226056, member: 39"] I have used the two diodes back-back on a few receivers in the past. A friend of mine brought me a dead shortwave receiver one time. I had no problem finding the problem as the frontend FET was split into two pieces. He said that when he disconnected the coax he drew a spark off the cable. :oops: For that RX I installed a series capacitor as well as the diodes. He never had another problem. BTW his problem was with static on a really loooooong antenna. As for sheer frontend overload from a commercial station, it does happen. If I was listening to the 10 Kw AM station I had to service when I drove into the TX site the audio would become a bit distorted and the 920 KHz signal could be heard over half of the band and nothing was heard on the other half. On the FM band, if I was listening to the 100Kw signal, my car radio would go dead as I drove into the FM site when I was about 6-700 feet away and then come back again if I parked right at the base of the tower. The base of the tower was in a deep signal null. Both cases of overload have nothing to do with regulations or purity of the TX'ed signal and have everything to do with the RX's ability to handle strong signals. The only time I have heard of a ham RX being blown out by too much RF on the front end was when my former boss forgot he still had his Kenwood R-1000 connected to the three tower AM array when he flipped the 1 Kw transmitter back on. :crying: No amount of protection was going to help in that case. He didn't fair too badley in the end, just a blown bandpass filter coil, a capacitor and the RF amp transistor. Not bad for about 225 [U]VOLTS [/U]of pure and direct RF injection. [/QUOTE]

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