Hi Ray Brown Kb0stn, hope you are having a nice day
PW> manual I have though.  It's for the BTL-301/304, instead of the 301/302.
RBK>   No problem. I'm glad you seem to have what I'm looking for! :-)
 You have no idea how close this (and the other) manuals came to being
landfill.  Was at one of the flea markets in S.A. and a guy was getting 
ready to leave and didn't want to haul a bunch of stuff back.  One of
the things I didn't get was what appeared to be a VHF-LO mobile.  At the
time just couldn't justify the space. :/  Was a Midland I think, huge
son of a gun too.
> And based on the design used, there's no reason why you 
> couldn't replace them with a synthesizer.
RBK>   Hmmm... well, I'll try to give you some info. The overall serial 
RBK> number is 216-B09065. The recieve board looks like a 1972 (sigh), it
 Does it have a listed reciever cert. number?  RL14A is 29-35, B is 35-44,
and C is 44-50.
RBK> says 500-943C on the solder pad, and the transmit board is a 1974 
          ^^^^^^^^
 That's good.  The L.O. uses a third overtone xtal fed to a tuned circuit
on gate 1 of a dual gate MOSfet.  (Q101)  The fet is also the first 
ransistor
after the input filter from the ant. connection.  The fet puts out the
10.7Mhz 1st. I.F. which is sent to the 10.245Mhz 2nd I.F.
A couple of things here, the input bandpass filter is *only* 1Mhz wide.  
Depending on what part values were used will determine what what band 
it was used on. That being said however, based on the alternate part values
given, you should be able to widen it up for all of 6M.
 Second, is that the 2nd gate has *NO* protection other than the caps in the
filter between it and the antenna, a 22K resistor to ground, and after a
100K, 680ê, and a 68ê resistor to the unreg. 13.8VDC source.
 I'd suggest either replacing it with one that has some overvoltage
protection built-in and/or adding some diodes to shunt any high voltages
away from it.  (me, I'd do both just in case)
The other is that in situations where there was strong image interference,
the 2nd I.F. was 11.155Mhz. (IC101) The xtal used will be marked as to which.
RBK>number 501-183C.
           ^^^^^^^^^
That's not *too* bad.  The biggest changes were the drop to 6 xtals,
and the power regulater being moved to it.  Anything done after 12/75 when
they revised the relay board (501-265) your own your own. 
A couple of things here, the xmtr is never powered up until you key the
mic.  At that point the rcvr is powered down.  What makes this interesting
is that you could use it as a repeater and not need to supply power to the 
xmtr until it was actually needed by just changing the relay hookup.
This is good if you had to run it off of a battery powered backup. No 
standby current lost to the xmtr.
 Another is that from what I get out of the reading is the swr protection
instead of shuting the finals off entirely, just reduces the power down
as the swr goes up.  The advantage here is that you at least keep putting
out a signal, which is handy in an emergency setting where you don't have
an optimum antenna setup.   (I know you know all this, but this is for those
who haven't quite gotten some of the *trick's of the trade* as it were down
just yet)
 Now for the really fun part.  :>
RBK> And, you're right, there's room for up to 12 crystals on each board. 
ow.
RBK> But, the possibility of putting in a VCO. even better than rocks! :-)
PW>  The reciever is tuned in 3 segments (29-35, 35-44, 44-50) and the 
PW>transmitter in 7. (29-32, 32-35, 35-38, 38-41, 41-44, 44-47, 47-50)
RBK> Sounds consistent with things I've heard about commercial rigs. And, I 
RBK>can say that this box should be in the highest segment of both rx and tx.
 While the rcvr uses (f-10.7)/3 for the L.O. the xmtr is a tad more
complicated.  In this case, I'd better quote the manual.  
(emission designator 16F3 btw.)
---------------------------------------------------------
CRYSTAL OCSILLATOR
 The Oscillator (Q212) is a common collector, modified colpitts type,
whose frequency is determined by use of one of 4 crystals selected
by the channel selctor switch. Each crystal has an associated trimmer 
capacitor which is used for fine frequency adjustment. When used with the
specified crystal type, the oscillator meets the required frequency stability
without need for crystal ovens or external compensation. The primary supply
voltage to the oscillator is regulated.
DIVIDER
 The divider (IC201) is a digital frequency divider which devides the output
frequency by 4.  The purpose of the divider is to allow both the oscillator
and the modulator to operate at their optimum frequencies.
MODULATOR
 A varactor, phase-modulator is used.
 The modulator, consisting of L206, CR205, CR204, and associated circuitry,
is an anti-resonant circuit tuned to 1/4 the oscillator freq.  The square
wave output of the divider is lightly coupled to the modulator by C241.
The harmonics are rejected by the selectivity so that the output consists
only of the fund. plus the two sidebands.  By varying the voltage on the
varactors (CR204,205) at an audio rate, the resonant freq. and consequently
the ohase shift of the modulator is varied which results in the divider
output being phase-modulated at the audio freq.  The pahse modulator stage
modulates with low distortion over a small phase angle.  The multplier
stages which follow increase both frequency and the deviation to
the desired value.
--------------------------------------------------------------
(whuf, are your eyes as tired as my fingers?? )
 It goes on to list the 4 transistors used to make to f*16 multiplier
and so forth.  At this point you have a 13.1 to 14.433...Mhz spread
for 50 to 54Mhz recieve and either a 12.5 to 13.5Mhz or a 3.125 to 3.375Mhz
spread for xmit.  While the step size for a 10Khz rate is a tad small, it's
well within the capabilities of most of the parts available these days.
 By way of example, call Analog Devices and ask for samples and data sheets
on the AD 7008-50, AD9830, AD9850, and AD9955.  Now those have some serious
tinkering possibilities. 
 (OH WAYNE  have you looked at them???)
 I've got one of each except for the 9955. (hehehe.....)
PW.>> a few part changes, and there was a module put out in '77 that would 
PW>let you go from 30W to 100.
RBK>  Hmmm!! Both sounds interesting! Wonder if there would be an external 
RBK>switch control on the 100w module, or it would just do 100w all the time?
 As a matter of fact, it was switchable.  All I have of it's paperwork is
the mod for the BTL and the test and tune up for the amp. (BAL-100)
Based on the tuneup chart it should have gone to 6 with no problem either.
PW> The manual and additions would run 100 or so pages copied 
PW>(half if done doublesided) 
RBK>   Hmmm... that many pages. At a self-serve copier shop, that'd be, what, 
RBK>$4? I can handle that, just for curiousity on this old guy, if nothing 
RBK>else. 
Hmmm... best case locally is (last time I checked) $.07 per copy.
And I dare not guess at doublesided.  Still shouldn't be that much.
(too bad I'm not still an emt, else I'd go to cityhall and copy it
for about a penny per. >:  )
RBK> You can give me your address, or I can look yours up in a Callbook, 
RBKor you can look _me_ up in a Callbook, or NetMail me here at this BBS
RBK>(since I'm da SysOp) or Email me at  rbrown@gxl.woodtech.com for details.
 I seem to recall that the callbook echo had my old address, but it might
be correct by now.  I'll e-mail it just in case though. I tried netmail
once but I don't think it made it thru.  (I'm a point <: )
RBK>   Thank you very much!!
 Quote Eek the Cat, "It never hurts to help."  
 -=> Yours sincerely, Paul Williams KB5IVG <=-
              KB5IVG@JUNO.COM
... "Hey...we treat Danny just fine..tenderizer works wonders."--Syndi
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