[NLRS] 2304?

[Dr. Gerald N. Johnson]

On 12/28/2016 8:48 PM, Larry Peterson wrote:
>
>
> Excellent to see some interest in 2304 Mhz.  Karl WD9BGA and I each
> bought transverters from SG-Labs.  See
> http://www.sg-lab.com/TR2300/tr2300.html  We also have 33cm and 23cm
> units.  I use this in sport radio during the warm weather when I activte
> SOTA summits or work hams via pre-scheduled contacts from lookout towers
> in WI.  I operate 2m, 125cm, 70cm, 33cm, 23cm and 13cm SSB and CW, but
> given the 50 pounds of equipment I carry up 12 to 35 stories, I choose
> perhaps three bands I'll operate in a given morning.
>
> I was very surprised how well the 13cm unit works.  Karl & I each used a
> small circuit board antenna that comes with this Bulgarian transverter.
> We were 8 miles apart and we had S9 or better SSB signals.  I then
> rotated my tiny antenna broadside, and Karl's sig was still very strong.
>
> Karl & I set the North American summit-to-summit record this summer
> using a 79 milliwatt MESH system and Pidgin chat mode on 2.4 GHz.  That
> was completely LOS.  We tried twice more and could not repeat the
> contact, so we are realizing how special that ultra-low power microwave
> contact was.
>
> Now in real operation, I will use my 27-element Directive Systems loop
> Yagi, with the SG-Labs transverter, with 70cm IF.  Per my Bird wattmeter
> it puts out 2 Watts.
>
> As far as an amp, I could use your help, Jerry.  I like the PE1RKI
> design.  He has many options.  See
> http://www.pe1rki.com/40watt13cm.html  I have sufficient LiFePO4 battery
> capacity to run one.  I wouldn't mind putting out 25 or so Watts.  But
> my problem is I do not know how to set up the T/R relay switching.
> Anyone with ideas would be appreciated.

That's where you need a sequencer. If your transverter has two coax 
connectors, on for receive and one for transmit, then you can add the PA 
to the transit side and go to the TR relay. RF relays don't survive well 
with RF present while closing or opening, and PA's don't survive well 
with full RF drive and the relay open for 10 milliseconds or so. 
Unfortunately virtually all IF rigs put out RF before they put out the 
TX output control line. One way to sequence is to run the microphone PTT 
(VOX not allowed, nor KOX) through auxiliary contacts on the TR relay 
but key the relay with the microphone PTT first. Paul Wade has a couple 
sequencer designs on his web pages, and there have been several 
published over the decades. On 10 GHz I thought I had some sequencing 
using the TXinh line of the IF rig with some delay on a transistor 
switching that bias off a modification of the DEMI TC, but my 10 GHz TR 
relay suffered. Now I have the IF (FT-857D) set up for PTT only for SSB 
and CW tx only with the PTT on the microphone pushed. So I'm using 
manual sequencing, manual PTT, then give it audio or start keying. Stop 
the audio or keying before releasing the PTT. Its working depending on 
the SSB transmitter not transmitting a crunch from the PTT switch or 
some kind of transmitter transient which isn't impossible.
http://www.geraldj.networkiowa.com/papers/CSVHF2010/TxinhtoTC.pdf

DEMI will sell their TC board kit separately from transverters. I have 
bought a couple for future projects.

If the transverter has only one RF connector, you need two TR relays to 
switch the PA in and out or one four connector transfer relay. I've been 
looking at lots of proceedings lately and W5LUA did have an article on 
applying the transfer relay in one of them. Possibly on the technical 
section of the NTMS web site. The only problem with a transfer relay is 
that it connects the PA input and output together when not using the PA 
so the PA has to be disabled to keep it from oscillating destructively.

73, Jerry, K0CQ
>
> 73,
>
> Larry WA9TT
>
>