[Milsurplus] Xtal for ARC-1

[Mike Morrow]

Larry wrote:

>I'd like to find a crystal for my R-28 and ARC-1 receivers for 144.450
>Mc

>I think the one for the ARC-1 is 7485 Kc.  Dunnow what it would be for
>the R-28 VHF receiver.


Hi Larry,

The crystal frequency for the RT-18/ARC-1 is given by (all frequencies in
mcs):

Crystal Frequency = (Carrier Frequency  - 9.72) / 18

So 7.485 mcs is correct for operation on 144.45 mcs for the RT-18.


The crystal frequency for the R-28/ARC-5 is given by (all frequencies in
mcs):

Crystal Frequency = (Carrier Frequency  - 6.9) / 24

So 5.73125 mcs is correct for operation on 144.45 mcs for the R-28.

>The ARC-1 unit is a CR-1B/AR holder.  Is it the same for the R-28 VHF
>command receiver?

The RT-18/ARC-1 can use CR-1A/AR (preferred) or CR-1B/AR units in the 10
external crystal sockets.  The CR-1A apparently is has better temperature
drift specifications than the CR-1B.

The R-28/ARC-5 uses a similar sized unit with same pin spacing but much
smaller pins.  It is Signal Corp type DC-31.  Also, the more common FT-243
crystal holder will fit.  The CR-1 series will definitely NOT fit.

73,
Mike / KK5F