[NLRS] Using a Radio Shack HTX-10 as a 28 Mhz IF

[John P. Toscano]

Jim Hermanek wrote:

> First, the step tuning I believe is selectable to 1 khz steps with a
> "clarifier" to tune (both xmtr & revr) within the the steps.....  This may
> be cumbersome to get used to, but for the price and the occassional use 222
> gets it may be an economical approach.

That should work OK, with the caveat that you won't necessarily know 
where you're tuned any more precisely than the minimum step size of the 
main tuning control.  Is the "clarifier" detented so that you could 
(conceivably) count "clicks" as you go, if you, say, want to "go up 10 
KHz" by turning the knob 10 clicks?  Or is it a "pure" analog control? 
I suppose if the latter (or in either case), one could jury-rig a 
frequency counter to tap into the RF somewhere and then watch the 
rightmost digits to know where you're tuned.  On the other hand, KA�PQW 
manages to tune all his radios without the benefit of being able to read 
the dials, and we all know he has plenty of success.

> I located a switched positive voltage in the diode switching that drives one
> of the transmitter driver amplifiers and plan to use that voltage to drive
> an isolating transistor stage that pulls up a relay that in turn grounds the
> transverter PTT.  Again, perhaps, a bit of a kluge, but a small relay board
> kit is available from DEM (#PTT 5X) for this purpose.    I'm also using the
> DEM transverter interface (AOS-28) to split out separate xmt & rcv plus
> attentuate the 22 watt output of the HX-10 to the 100 mw max of the
> transverter....

This may be "overkill" for the purpose.  The AOS-28 will RF-sense and 
automatically do the T/R switching for you.  Phil (KB�NES) has his 222 
transverter working that way (though not with an HTX-10).  Of course, a 
"true" PTT is preferred, since on SSB, an RF-sensed relay may drop out 
on the low points of your speech if it doesn't have enough hysteresis 
built in.  The nice thing about your approach is that you will get a 
"hard" PTT signal, but if it somehow fails, the AOS will also detect RF 
and switch the T/R on transmit anyway.

Another approach would be to build a little box that you plug the mic 
into, and detect the press of the PTT switch there, and feed the PTT to 
the radio and transverter from there.  This could also be a convenient 
spot to place the CW circuit mentioned below.

> As for lack of CW operation, some who have tried to QSO with me on CW will
> not miss the lack of CW on the HX-10, but I am planning on building up a
> small oscillator to inject into the mic line for this capability.

Good luck with it all.
73 de W�JT