[NLRS] Suggested FM Simplex Freqs For Radio Contesting

[Dr. Gerald N. Johnson]

I found 7 US repeaters in the 2010/11 ARRL repeater directory with 
inputs on 52.550. From Maine to Texas, plus another in Nova Scotia. 
Rather close to 52.540.

Yes the rigs were very narrow banded in the receivers and didn't move 
frequency easily. That's why 2m repeaters are low input on 146 and high 
input on 147, the transmitters had greater bandwidth than the receivers. 
And the receivers were double conversion using the same crystal for both 
conversions with serious adjacent channel rejection (for 30 or 60 KHz 
channel spacing) achieved in the first IF. So long as the receiver was 
kept single crystal, changing frequency required realigning that first 
IF after a small move. Changing the circuit to use two crystals improved 
the agility without compromising performance, except that especially in 
mobiles there was NO room for another oscillator tube and crystal. And 
most base stations were mobile chassis with a different case and power 
supply.

Scanning the repeater directory there are many repeater outputs in 51 
though most are 53.

Crystals didn't cost all that much in dollars, but hams using surplus 
are cheap. I ground my own, probably only took a few days to grind that 
900 kHz rock up to move the transmitter output from 37.1 to 52.525. And 
some skin. I recall I used 400 grit wet or dry paper wet and my finger 
tips lapped over the corners of the crystal and were sandpapered more 
rapidly than the quartz, but without noticeable pain because the 
sandpaper was wet. The crystal frequency was low because phase 
modulation had to be multiplied many times to achieve the desired 15 or 
30 kHz deviation. Best I recall that transmitter crystal started out 
more than 3/16" thick and lost about a quarter of the thickness. Wet or 
dry laying on a sheet of plate glass was a lot faster than kitchen 
cleanser with the soap washed out leaving only the abrasive, but washed 
kitchen cleanser was a lot nicer on the finger tips. If one ground many 
crystals, the plate glass had to be replaced from wearing it away from flat.

73, Jerry, K0CQ

On 12/17/2012 3:45 PM, S. Earl Jarosh wrote:
>
>
> To get back on track the only accepted simplex Freqs in 6m are:
>
> 51.490
> 52.510
> 52.525
>
> And
>
> 51.100 - 52.000
>
> Everything is in 20Khz steps with the exception of 52.525
>
> 52.540 is only 10Khz from the first repeater pair above 52.525. I recommend
> against the use of 52.54 as it has a greater possibility of band opening
> repeater interference.  As Jerry said before 6m FM has its history in Xtals
> and equipment that was not very wide band.  Xtals were expensive so 52.525,
> 52.55/53.55 with 53.55 talk around allowed for 3 channels FM mobile with
> little adjacent channel. interference.  There are a number of 52.55/53.55
> repeaters around the country including here in Ramsey.
>
> Also on 70cm it is 12.5Khz so 445.9875 and 446.0125 are still usable for the
> future.
>
>
> Please refer to http://www.mrc.gen.mn.us  for the MN band plans which with
> some minor exceptions are pretty much in sync with the ARRL national band
> plans
>
>
>
> S. Earl Jarosh, N0HZ
> Cell:  612.868.1313
> Off:   763.545.3275
> Home:  763.546.7897
> Fax:   763.546.7897
> earl at moneycenters.com
>
>