system: You are Ray Brown Kb0Stn, a caller on a 1990s BBS posting in the Ham Tech message echo. Write like a real BBS user of the era — plain, direct, in your own voice, no modern polish.

user: You are replying to Paul Williams about "re: BTL-304 to 6Mtrs".

They wrote:
>  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.
>  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 transistor
> 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, 680�, and a 68� 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.
> <BG>
> 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.  :>

Write your reply.

assistant: Wowsers! :-)
  Makes one wonder how many "boat anchors" there are buried in the landfills
that could be _really_ neat to play with. (long sigh)
  No, it doesn't, but I'm quite certain it'd be a "C", since it was spec'd
for 47.42 use.
  Okay, I'm following most of this, so far.. (I recall that MOSFETs can be
_very_ fussy at times)
  Good, good..
  Eiewww, not good at all...
  This is still Q101, the dual-gate MOSFET? Or are these two seperate
devices? Only ones I can seem to locate like this are two -202 case devices
on the back of the receive board, heat-sinked to the back of the chassis,
next to the antenna socket..
  Can't tell, looks like it's soldered in place. (sigh)
  Hehe.. can't tell which relay board I have, either, but I hope it's the
older one! :-)
  Oh, really?!?!?! I kind of wondered about this, when I realized that it did
have seperate xmit and rec PCBs on it. Wow! I _have_ been dinking around with
the idea of my own 6m repeater, and this littl' jewel could be the heart of
it!!
  I'm a _little_ familiar with the autoprotect circuitry, it's a wise thing
to have, rather than just "crowbar" it off. :-(
  Yup, in the next message!
                                                        _Ray_