Yaesu ft-736R - anybody using

[Rickie Sexton]

Is anybody using a Yaesu FT-736R with SkyRoof?  wondering how you set it up?

[John Oppen]

Hi Rickie,

Thanks for asking the question.  I am very interested to see if anyone else responds because I'm also using Skyroof and an FT-736R.  However I have not really used them together successfully yet, so I'm afraid I don't have the solution you probably want.  

So far I've been trying to keep Skyroof (feeding an SDRPlay RSP1A) on an all-RX system to avoid the inevitable error of transmitting into the SDR if they share any coax cables.  I have literally been changing the antenna and cabling setup several times per day lately to cover different bands and try different configurations.  I had originally thought I'd just run the yagi antennas on the receive SDR into Skyroof, possibly using band specific preamps and a diplexer to combine both bands into a single feedline to the shack/SDR/Skyroof.  My reasoning was that I could transmit from the FT-736R on an omni vertical and use more power if needed to overcome the lack of gain if needed, but that's obviously less than ideal.  I haven't tried that full setup yet, but it occurred to me later that the 2M yagi would pick up the uplink and send that massive signal straight to the SDR.  In fact, I just tried a CW contact on the last pass of RS-44 in a simpler version of that configuration and the SDR was so overloaded that it was unusable.  I'm running a 435-18C yagi and Halibut Electronics "AmpNOGS" preamp directly into the SDR.  I haven't tried using a diplexer to filter out the uplink yet, with the 2M port terminated as a crude high pass filter, so that might help.  I'm also using a broadband preamp so a dedicated, tuned 435 MHz preamp might help, but probably not enough.  That's on the list of things to try next.  I'm on the hunt for some reasonably priced or homebrew bandpass filters for the satellite portion of the UHF ham band.  AMSAT used to have plans for a simple "Mode J Filter" that might be worth building

So I'm taking a step back to rethink my plan.  I may just try using the FT-736 alone, old school, for actual QSOs and use Skyroof for listening only.  But I really am enjoying the SDR waterfall and auto doppler correction of Skyroof, so I'd like to find a solution that incorporates Skyroof into the QSO stream.  Perhaps increased separation between uplink and downlink antennas along with some good filters would be enough.  I've also been thinking of using relays to switch antennas around, maybe even a transfer relay to swap which radio sees V and UHF antennas, and just use the Yaesu as a transmitter, ignoring it's full duplex capabilities.

One idea that's possible, especially if you only use one mode like VHF up/UHF down, might be to split the UHF line with a proper -3dB splitter to feed the SDR and FT-736 UHF port, but one millisecond of carelessness would smoke the SDR and splitter.  Perhaps the DC on coax system could be used to attempt a safeguard system, but that's a bit too dodgy for my liking.  And I don't want to eliminate the ability to listen on VHF either, so that's a non-starter for me.

BTW, it seems that a lot of folks haven't heard of the Ampnogs preamp, mentioned above, so I'll provide a bit of info here since someone will likely ask.  It is relatively new to the market and was designed to be paired with an Eggbeater antenna for SATNOGS reception.  It is very broadband, incorporating little filtering, but it does include a T/R relay activated by 5V up the coax on RX and bypassed with no DC voltage.  This preamp is, by far, the least expensive preamp with any sort of TR switching that I know of, but it does not sense RF, so you have to be careful about how/when you enable and bypass the preamp if you intend to transmit with it inline.  Most of you already know that having a decent preamp at the antenna is much, much better than at the rig and this enables it with bypassing capabilities.  I have only played with it a bit, but it seems to work pretty well and has a noticeable increase in gain when the bias voltage is applied.  It's spec'd at 18 dB or so of gain.  I forget the specified Noise Figure, but it's pretty decent.  I'll test it one of these days, but not likely before the holidays.  I don't think the datasheet is on the website yet, but Mark can send you the details if you email him.  He also has some filters to eliminate AM/FM overload, but I haven't tried those yet.  See more and order at https://electronics.halibut.com/eggnogs/.  Mark is a really sharp guy trying to make a business (Halibut Electronics) of supplying niche ham gear, so I like to support him and I encourage others to do likewise.  

I literally just joined the Skyroof group, so I have not studied the other postings yet.  Maybe some other folks have ideas from other rigs that would help.  I probably should have done that before making a lengthy post, but I wanted to share my thoughts in response to Rickie's question.

Skyroof is the most exciting, fun and useful piece of software I've used in a long time.  It has taken my satellite game to a new level and renewed my interest in chasing the satellites.  Kudos to Alex for making it!!!  I'm looking forward to learning how to utilize it more effectively from the group.

John, KJ6HZ