[ARC5] Vet's BC-669 Project: "First Light."

[David Stinson]

The project to stand-up a BC-669 for our retired tugboat skipper is 
coming together well.  The RF deck I was using has a lot of issues, and 
given that just about the only things a BC-669 can tune is the 160 and 
80 meter ham bands, I decided an RF deck with the BFO module installed 
would serve him better.  Had a decent Hallicrafters RF deck with a 
"parts" mod deck and this good Electrical Research Laboratories 
modulator, so made "one good one out of two."  Yeah, yeah, I know.  Hey- 
they're getting revived and I don't think he'll mind, LOL :-D

Found more "Golden Screwdriver" booger-ation in the Modulator deck.  The 
main switching relay (which controls the TR relay with which we are 
familiar) is one of those "Hi-Z" coils that works by sending the Lo-B+ 
(250V) through a 25K current-limiting resistor, then through the relay 
coil to ground.   PTT contact would not pick the relay.  Someone 
replaced the limiting resistor, but soldered it one terminal lug off; 
the relay had no voltage source.  When that didn't work, he unsoldered 
the new resistor and replaced it with 10k, I suppose thinking more 
current might make it pick.  Nope.  Like the majority of Ham mods, he 
got a little "deep" and abandoned the project.   Removed the error and 
installed the 25K.  Relay now operates correctly.    Replaced bad caps 
and bad resistors in the transmitter circuits and time for testing.  
Borrowed two "hot" 807s from the Aussie rig and transmit crystals for 
3890 and 1950 KC and started tuning.

First- SLOOOW DOWN.  If one gets in a hurry, it's easy to stick one's 
hand back in to tune the coils and forget to un-key the transmitter 
first, which will result in an RF burn.  It's also very important to 
make certain C53, the .002 uFd plate B+ blocking capacitor, is in good 
order.    Clean and lube the sliders with De-Ox-It before tuning.  The 
moveable taps are designed for finger pressure be applied toward the 
coil while moving them.
*It is very important to tune the BC-669 transmitter according to the 
manual procedure.*  Attempting to "wing it" will waste your time and 
power out.     The only exception I found was an extra step of moving 
the 160M taps on the PA Tank coil, "A" side, up a few more turns than 
those specified. Tuning a BC-669 can be tedious; there is only one 
"correct" setting for the taps on each of the channel settings, but once 
the first 160 Meter channel and the first 75 Meter channel are done, the 
other channels are identical or close settings, so once done, it's 
done.    Again urging that one follow the manual procedure, here are the 
tap settings for 160 and 75, assuming a 50-Ohm non-reactive load:

PA Tank Coil (smaller one with two taps per channel,
the tap sliders are labelled P and A, 1 to 6):
Coil sliders on the "P" side facing the back of the rig:
160M: 7 clicks from the top.  75M: 11 clicks from the bottom.
Coil sliders on the "A" side facing the front of the rig:
160M: 9 clicks from the bottom.  75M:  5 clicks from the bottom.
Coil sliders on the Antenna Loading coil
(big one behind the door, taps L to R, 1 to 6):
160M: 10 clicks from the top  75M: 5 clicks from the top.

With good tubes and a spec power supply, you should get 50-55W carrier 
output on all channels.  Measured with my calibrated 'oscope, that is 
what this one is making, with good 100% plate modulation from the four 
Class AB1 6L6s in the Plate Modulator. First contact was with Ralph, 
KD6OS in Oklahoma.
Video link: Vet's 669, first contact 
<https://www.facebook.com/AMRepublic/videos/394902111176049/>
Will check into our local AM net on 3890 KC tomorrow morning, barring a 
work call-out.  Still some work to be done on the set and crystals to be 
found or etched, but we're "in the home stretch."

Some of our great members have donated.  Bill, your 3880 crystal arrived 
today, Many Thanks!
If you would like to donate to the cause, still need these crystals in 
any holder FT-243/HC6U or larger:
1885 1500 2270
1985 1600 2370
3665 3280 4050
3885 3495 4265

TNX ES GL OM DE Dave AB5S



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