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+--- Thread: Using FT-857 or 897 with transverters (/thread-656.html)
Using FT-857 or 897 with transverters - VK7HH - 04-10-2018
Hi All,
I'm after anyones experiences with using a FT-857 or 897 with transverters.
I've been led to believe that these rigs in particular have high RF power spikes on transmit, even when the power level is set to minimum, which, I'm afraid of blowing up my transverter I have coming.
Transverter will be a SG Labs 1296 one. From a few other posts I have read, nobody has reported any issues, but I wanted to double check with anyone on the forum who may have had issues?
857 is actually the rig I will be using in a remote configuration, so I will have a coax relay switching RF from the 2m output of the radio between a 2m amplifier and the IF input of the transverter with power being set on the radio to 5W maximum.
Regards
Hayden VK7HH
RE: Using FT-857 or 897 with transverters - VK3LU - 04-10-2018
Hayden,
Have a look at this site.
http://ad5x.com/articles.htm
The article at the top may be of assistance.
Nev
RE: Using FT-857 or 897 with transverters - VK4VU - 04-10-2018
Hi Hayden,
Coincidentally this exact topic has very recently been discussed on the WA1MBA Microwave Reflector.
I've copied this response from Gerry K0CQ, which refers to a paper he has written detailing a setup procedure that reduces the incidence of power spikes in your application.
Quote:"Message: 1
Date: Mon, 01 Oct 2018 21:25:46 -0500
From: "Dr. Gerald N. Johnson" <geraldj@netins.net>
To: microwave@mailmanlists.us
Subject: Re: [Mw] FT-817/818 Questions
Message-ID: <5BB2D72A.2030308@netins.net>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
I have run an 817 on 10 or 24 GHz a few times. For my own 10 GHz rig I prefer my FT857D. The DSP is good at reducing the audio noise bandwidth on SSB. There is audio noise beyond the SSB filter because the filter is in front of several IF gain stages in nearly all radios. The DSP CW filter is narrower than I care for. The 500 Hz mechanical IF filter definitely improves the S/N of weak signals, the DSP doesn't as far as I can tell.
One option of the 857D that is not available in the 817 is running CW in SSB mode. All it takes when enabled is to close the key to transmit CW while listening in SSb mode. I have that disabled in my 10 GHz rig because it gets RF to the antenna relay while its moving and that hot switching is hard on tiny microwave relay contacts. I do use that automatic CW option with the home station 857Ds for HF, VHF, and UHF operations. For transverter service I require squeezing the microphone PTT button to get any RF out on CW or the internal CW beacon. That manual sequencing protects the microwave antenna TR relay.
I went into the main alignment menu and reduced the 2m TX gain to reduce the output down to 2 watts rather than depending on the front panel setting. The front panel setting uses ALC and often spikes at the beginning of each transmission which is not good for the transmit side of the transverter that needs only a couple watts or less. Actually the transmit mixer probably needs only a few milliwatts. Lowering the transmitter gain prevents those ALC spikes in all modes including FM. I checked it with my Tek 475 200 MHz bandwidth scope and I am sure there are no spikes. I wrote an article for CSVHF in 2010. I have a version on line at:
http://www.geraldj.networkiowa.com/papers/CSVHF2010/xvtr857align.pdf
I haven't tried a fixed DC bias into the external ALC jack on the back of the radio.
The 857d does draw a couple amps on receive, twice that of the 817 but it has more front panel controls than the 817 and I think some more options. I don't use RIT. The 857D isn't enormously larger than the 817.
73, Jerry, K0CQ"
Hope this helps
73
Rod VK4VU