Two Radios Sharing HF Antenna Question

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TailGator911

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I have an Icom R75 that will soon be fed with a PAR end-fed long wire, the coax feed first going into a Grove Tune4 preselector/tuner/preamp where I plan to split the other half of the signal to an Icom 746pro right next to it, using the HF portion to monitor shortwave broadcast and utilitiy bands. I do not transmit on the HF bands as I am not licensed (yet) , but I do transmit on 2m/440. The Icom 746pro will have a Cushcraft AR270 antenna feeding the 2m side. If I transmit on a separate VHF antenna on the 746 (2m) while hooked up to the longwire from the Grove Preamp separately feeding the R75, will the RF damage either the Grove TUN4 or the Icom R75? I am finally rebuilding the shack and just unboxed the TUN4 and wondered about this and had one of those over-60 moments. Some of you might know what I am talking about. Thanks in advance!

John
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db_gain

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You should be fine for the most part considering the bands in use, just don't tx directly into the r75.
 

ElroyJetson

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DO NOT ASK ME FOR HELP PROGRAMMING YOUR RADIO. NO.
I would not recommend it. That sort of thing is what keeps radio repairmen busy and cursing at their dumb customers under their breath.

Never mind the SWR issues that would arise from running two radios on one antenna, you're trusting that the filters in the receiving radio are going to be able to resist the power of the transmitter and that is probably a false assumption.

The R75 is a RECEIVER. It is not part of a transceiver, which WOULD be designed to handle out-of-band transmit power. Do not assume it can handle tens of watts on its input even far out of band.

You'd better call Icom tech support just to be sure but I would not recommend doing it. I personally would not consider it.
 

TailGator911

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What I was thinking and hoping to hear. Yes the 2m signal (antenna /transmit/ coax) will be physically separate, direct from the AR270 into the 2m connection on the back of the 746pro. But I was just wondering if the RF from the 2m transmit could somehow go up into the hf receive line from the TUN4 that will be connected to the HF port at the back of the 746, sharing the SWL line with the R75. I sure would hate to burn everything up. Thanks
 

TailGator911

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Thank you Elroy. Always good to hear the opposing opinion. Yeah, because the replies to this question are split (I have asked others aside from RR and get totally different opinions as well) I feel a call to Icom technical support coming on. I dont want to lose a radio!

Thnx

John
 

TailGator911

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Just had a very pleasant and informative conversation with Mike @ Icom Tech Support. Should of done that in the first place but what with all the foreign call centers and such I tend to hesitate there. Mike told me if I transmitted on my configuration that I would certainly damage the receive end, both the TUN4 and the R75! He said the port is open on the 746 and it would definitely transfer harmful RF up the receive only line. He was nice enough to refer me to a website business that is owned by an ex-employee who builds and sells several neat gadgets for all kind of situations.

The part he referred to me is called a "Beverage Antenna Port Saver for ICOM 756 Series Transceiver" he told me it will work on all Icom transceivers. It is only $30 and they take PayPal.

The site is here, called SultanTronics,...SultanTronics Radio Repair and Technical Design Services Lots of neat stuff here. So not only did Mike answer my question, he offered a very affordable solution to my problem and most likely saved me a heckuva repair bill. I have his private extension and he offered his help anytime. Too cool.

Icom Tech Support gets a 10+ in my book!

Hope this helps out anyone with the same dilemma!

John
 
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