[Milsurplus] RT-68

[ersmar at comcast.net]

Mike et al:

     Lest we turn our backs (pun intended) on PRC-25's or -77's because of their need for 150 Hz tone to open the squelches, keep in mind they ALL have the ability to operate open-squelched.  A real PITA but it does work.  I've used my -25 for a couple of JOTA Scout demos (BTW, teenage boys love to run around with these things on their backs) and at the MRCA meet in Gilbert.  Loads o' fun in spite of the incessant hssssssssssssssssssssssssssssssssssssssssss..........

     And I've had my -25 talk with my IC-746 PRO at QRP on 51.0 with no trouble.  If you want to be a purist about it, you can hold the -25/-77 handset away from your mouth a bit and reduce the modulation swing and send a les-overdeviated sig to the NBFM rig.  But I've not found this to be a problem.  I'm not likely to mess with the innards of the handset or the rig to reduce deviation.

73 de
Gene Smar  AD3F


 -------------- Original message ----------------------
From: Mike Morrow <kk5f at earthlink.net>
> Ray wrote:
> 
> >I along with many others have been using wide band military
> >radios at hamfest and other events for years on 51.0 We make
> >no attempt to modify their bandwidth to comply with modern
> >5 KHz radios...
> 
> That's always seemed to me to be the best approach to take with any type of 
> vintage gear...operate it the way the folks who designed it decades ago 
> intended.  As far as the RT-68/GRC goes, I've always found that unit to be a 
> fascinating piece of engineering, especially for something whose design goes 
> back more than 60 years.  It must have cost an arm and a leg...too bad they 
> couldn't have come up with something a little more durable than a decal as the 
> nomenclature plate.
> 
> For something a little more modern, with a little narrower deviation, and with 
> the capability to work reasonably well with modern ham gear, get a AN/PRC-25 or 
> -77.  Another mil set that is much smaller and works very well with modern stuff 
> is the mid-1970s AN/PRC-68.  These sets generate the standard 150 Hz sub-audible 
> squelch tone required by most post-1950s military FM gear, but the AN/PRC-68 
> requires only carrier to break the squelch.  The AN/PRC-25 and -77 require a 150 
> Hz tone, but I've found that setting a ham unit to emit the close standard PL 
> tone of 151.4 Hz will satisfy these radios' squelch system, as well as that of 
> the AN/VRC-12 series of mobile sets.  Speaking of that series, the successor to 
> the RT-68 was the early 1960s RT-524/VRC.  That unit is pretty easily found in 
> surplus (but be careful that it hasn't been de-militarized).  It makes an 
> excellent FM radio, tuning 30 to 76 MHz in 50 kHz increments.  But you have to 
> feed it 24 vdc.
> 
> >Most operation on six in our area is SSB or on the occasional band
> >opening for FM so you wonÂ’t get a lot by modifying your 68 and
> >operating it at home
> 
> Very true words.  
> 
> I keep an old scanner on 51.0 MHz, but I have very very seldom ever heard any 
> activity from a band opening there.
> 
> Mike / KK5F
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