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Easy SSB Adapter for R-390A
Just in case anyone is interested:
I got tired of looking / waiting for the "real" SSB adapter for the R-390A ( or a usable substitute ) and didn't want to put any mods into my radio. Here is my fast and semi-dirty solution. It provides an external adapter that works from the 455KC 50 ohm IF output on the rear of the R-390A. I bought a bad Yaesu FRG-7700 general coverage receiver off of ebay. It had a destroyed display section, but was otherwise ok. I disconnected the cable from the antenna connector and ran a wire from the connector and through a shiny new bright orange .047 uF cap to the collector of Q-23 (which is actually on the secondary center tap of T-09). Then I just ran a cable from the IF out of the R-390A to the antenna input connector on your new adapter. End of mod. You now have selectable USB/LSB/AM(with 3 bandwidths), 3 more IF amps, usable AGC (kinda), S-meter, and Audio amp with speaker, phone jack, recorder output and tone control. It works great. If you are using a working FRG-7700, you could leave the radio intact and add a bnc connector to run the IF input. I decided to gut the rest of the Yaesu out and have a stand alone, no extra knobs, adapter. I removed the entire PLL / logic board (??? whatever they call the bottom board ) and everything that wasn't related to audio, IF, and the product detector. This left the top board , power supply and audio stuff. My scientific approach to eliminating unneeded circuitry was listening to the R-390A through the adapter and one at a time unplugging internal connectors in the 7700. If nothing stopped working I left it unplugged and went on to the next connector. After doing that I removed all disconnected cables and any boards that no longer had anything hooked to them. These boards were then sold on Ebay (boards, VFO, memory board etc) If anyone else has already done this, I'm sorry I claimed credit for the idea.... havn't heard of it anywhere before. The same idea could probably be done using any old receiver with a 455 IF and product detection at that frequency. E-mail any questions or comments to: 73 Bob WB8CAC http://www.qsl.net/wb8cac |
One thing I forgot to mention is that with this "adapter" sideband
selection is backwards. To make the switch marking reflect the actual sideband being received, reverse the wires going to pins 2 and 3 of P-14 which plugs into J-10. 73 Bob WB8CAC http://www.qsl.net/wb8cac |
....or you can take the IF output and feed it to the antenna connection of a
radio that will tune 455kc. It was someone else's suggestion from one of the R390A lists. I tried it with my Kenwood TS440S/AT and it worked just fine. Barry - N4BUQ Just in case anyone is interested: I got tired of looking / waiting for the "real" SSB adapter for the R-390A ( or a usable substitute ) and didn't want to put any mods into my radio. Here is my fast and semi-dirty solution. It provides an external adapter that works from the 455KC 50 ohm IF output on the rear of the R-390A. I bought a bad Yaesu FRG-7700 general coverage receiver off of ebay. It had a destroyed display section, but was otherwise ok. I disconnected the cable from the antenna connector and ran a wire from the connector and through a shiny new bright orange .047 uF cap to the collector of Q-23 (which is actually on the secondary center tap of T-09). Then I just ran a cable from the IF out of the R-390A to the antenna input connector on your new adapter. End of mod. You now have selectable USB/LSB/AM(with 3 bandwidths), 3 more IF amps, usable AGC (kinda), S-meter, and Audio amp with speaker, phone jack, recorder output and tone control. It works great. If you are using a working FRG-7700, you could leave the radio intact and add a bnc connector to run the IF input. I decided to gut the rest of the Yaesu out and have a stand alone, no extra knobs, adapter. I removed the entire PLL / logic board (??? whatever they call the bottom board ) and everything that wasn't related to audio, IF, and the product detector. This left the top board , power supply and audio stuff. My scientific approach to eliminating unneeded circuitry was listening to the R-390A through the adapter and one at a time unplugging internal connectors in the 7700. If nothing stopped working I left it unplugged and went on to the next connector. After doing that I removed all disconnected cables and any boards that no longer had anything hooked to them. These boards were then sold on Ebay (boards, VFO, memory board etc) If anyone else has already done this, I'm sorry I claimed credit for the idea.... havn't heard of it anywhere before. The same idea could probably be done using any old receiver with a 455 IF and product detection at that frequency. E-mail any questions or comments to: 73 Bob WB8CAC http://www.qsl.net/wb8cac |
On 02 Feb 2004 00:56:36 GMT, (N4BUQ) wrote:
...or you can take the IF output and feed it to the antenna connection of a radio that will tune 455kc. It was someone else's suggestion from one of the R390A lists. I tried it with my Kenwood TS440S/AT and it worked just fine. Barry - N4BUQ I tried that with the FRG-7700 before going directly into the IF. Got noticably better sig:noise without the RF amp / mixer and misc noise of using the entire receiver. On the bright side of using the complete receiver, you can tune back and forth across the IF for PBT. 73 Bob WB8CAC http://www.qsl.net/wb8cac |
On Mon, 02 Feb 2004 02:11:11 GMT, (Robert) wrote:
On 02 Feb 2004 00:56:36 GMT, (N4BUQ) wrote: ...or you can take the IF output and feed it to the antenna connection of a radio that will tune 455kc. It was someone else's suggestion from one of the R390A lists. I tried it with my Kenwood TS440S/AT and it worked just fine. Barry - N4BUQ I tried that with the FRG-7700 before going directly into the IF. Got noticably better sig:noise without the RF amp / mixer and misc noise of using the entire receiver. On the bright side of using the complete receiver, you can tune back and forth across the IF for PBT. 73 Bob WB8CAC http://www.qsl.net/wb8cac You have to attenuate the IF signal when doing that or it will overload the receiver and you get all the noise you mentioned. 73 Gary K4FMX |
I've got an NE602 based SSB detector up on my website. Works well.
Pete "Gary Schafer" wrote in message ... On Mon, 02 Feb 2004 02:11:11 GMT, (Robert) wrote: On 02 Feb 2004 00:56:36 GMT, (N4BUQ) wrote: ...or you can take the IF output and feed it to the antenna connection of a radio that will tune 455kc. It was someone else's suggestion from one of the R390A lists. I tried it with my Kenwood TS440S/AT and it worked just fine. Barry - N4BUQ I tried that with the FRG-7700 before going directly into the IF. Got noticably better sig:noise without the RF amp / mixer and misc noise of using the entire receiver. On the bright side of using the complete receiver, you can tune back and forth across the IF for PBT. 73 Bob WB8CAC http://www.qsl.net/wb8cac You have to attenuate the IF signal when doing that or it will overload the receiver and you get all the noise you mentioned. 73 Gary K4FMX |
"Gary Schafer" wrote in message ... A modern day Q 5R ! 73 Gary K4FMX Mad Man Muntz came to mind.... |
" Uncle Peter" ) writes:
"Gary Schafer" wrote in message ... A modern day Q 5R ! 73 Gary K4FMX Mad Man Muntz came to mind.... But he was known for taking things out, while the scheme in the original (it's been so long) seems way overly complicated. After all, the Q5er was adding selectivity to a lousy receiver, while this uses a whole shortwave receiver when only a BFO is needed, and that receiver doesn't have better selectivity than the main receiver. It seems more like a Rube Goldberg scheme. Michael VE2BVW |
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