ARC T-20 VHF Model?

kd4e doc at KD4E.COM
Thu May 21 19:24:09 EDT 2009

Wow, neat!  Learn new things every day!

So if crystals are changed to 2M and a bfo is added the R-19 
can receive 2M AM,
CW, FM (slope detection), and SSB.

Then in the T-20 PM modulation could be added and the AM 
altered to DSB,
then it becomes an AM (DSB reduced carrier), CW, FM, SSB 
(DSB suppressed
carrier) 2M QRP TX.

Or maybe just put them on 2M Packet!  ;-)

Really need the schematics for these rigs to see how 
practical this all may be.

Also need to discover if the control heads are available or 

As a teen I used to pour over the Fair Radio and Nebraska 
Surplus catalogs
and dream of owning this type of radio.  Sure would be fun 
to finally do it.

> whistle tuning also known as whistle stop tuning. A spotting feature,  
> allowed you to zero beat the continuous tune receiver to the transmit crystal  
> for simplex operation.  Aircraft receivers of that era often did double  duty 
> and were used to receive nav signals  as well as voice.  Also  there were 
> standardized calling frequencies like 122.1 mc for Flight Service,  122.5 
> standard civil tower, 126.2 standard military tower, 121.9 ground control,  
> etc. You would transmit on a "standard" frequency and listen on a facilities  
> "discrete" frequency if you didn't have a crystal for the facilities discrete 
>  frequency.  An example might be you wanted to talk to say, Louisville 
> Tower  whose frequency was 119.8 but you didn't have a 119.8 crystal installed.  
>  You would tune the receiver to around 119.8 and listened until you heard  
> Louisville tower talk to someone and fine tune that. You would have the  
> transmitter set to 122.5 and call Louisville Tower and listen for him on  119.8.
> One reason it was still useful and practical to know the light gun signals  
> back in the day....................
> Emil WD4SCZ   ( N88421 in aeronuatical service)
> I will have to read-up on the "whistle tuning"  feature.


Thanks! & 73, doc, KD4E
Free OS :
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Have an day!

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