[AMRadio] deliberate encroachment


rbethman rbethman at comcast.net
Sun Dec 6 12:06:08 EST 2009


The whole matter brings a lot of interesting area for discussion.

The AM Window thing is an ancient "Gentleman's" agreement.  It's time 
has passed, and we aren't "stuffed" into a corner.

The "issue" of rock bound with Vintage Military equipment makes me laugh 
hard enough to worry about spraying coffee on my keyboard!

My Tx is one of two BC-610s, and the Rx end is either an R-390A or a 
Northern Radio SP-600.  So I'm well acquainted with the "vintage" realm.

As to the rock bound element, the FT-171 crystals for the BC-610s are 
the ones left over from the same time frame as the radio.  You can't go 
to the last of the crystal companies and order some.

So when I plug one into the Beast, I've already discovered that they are 
NOT on the stated frequency.  No amount of cleaning has resolved it.  
Two different 3945Kc crystals have two different frequencies of 
oscilation.  One is up about 3Kc, while the other is down about 2Kc.

Then I have multiple Tuning Units for that frequency range.  The output 
frequency varies dependent on which one is used.

I'd have to tag everything, and create tables for the whole mess.

In lieu of that, I use the TUs in the M.O., (Master Oscillator), mode.  
I use a frequency counter with a lead draped over that section of the 
Tx.  Those little knobs, coupled with the very little capacitance being 
varied over 500Kc, makes it problematic.  It takes an hour of warm up 
time to get "reasonable" stability.

I'm as close to the frequency desired as I can get it.  Unless someone 
wants to procure a PTS-40 frequency standard that I can't afford, I'll 
have to continue the way I go.

I don't light up the plate without listening, but I "may" step on 
someone that I can't hear.

It "can" be very broad, but I am careful as to the mic gain, monitoring 
with an SM-220 with the Panadaptor.  I even feed the receiver's IF into 
the SM-220, to watch the signal even when the Rx is muted.

Keep looking for the sunspot activity, but the "other" hobby, Astronomy, 
has the whiz banhs predicting a significantly lower number than was 
originally predicted.  I'm seeing the same with my telescopes.

I guess we are stuck in the same old conundrum of antenna orientation, 
propagation, and little variances in frequency.

Collisions will continue to occur.  They have for my 29 yrs of being 
licensed, and I don't expect it to really get better.

One simply should not fire up on a schedule if a QSO is ongoing.

Jim and Brian:  You are both doing a great job!

Bob - N0DGN


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