[CQ-Contest] C-Line Comments

k8cc k8cc at mediaone.net
Fri Feb 2 18:32:27 EST 2001

The praise of the T4XC/R4C combo by W4AN and KR6X is accurate and highly
deserved.  During the late 80s the C-Line was my radio of choice.  My
station eventually evolved to the point that during this period I was doing
SO2R with three C-Lines (two at a time).  Arranging the gear for easy
accessibility to the single op took some thought.

I remember seeing a picture of N6TR in one of the contest writeups where it
appeared he had five T4X's and a single R4C.  (Of course this was before
Tree discovered SO2R...)  Pretty cool for its day.

I eventually gravitated away from the C-line like most others for a modern
solid-state transceiver.  I tried a lot of the rigs of that era and just
wasn't satisfied with any of them until the IC-765 came along.  Not that
the IC-765 was better, but it was good enough that the few disadvantages
were outweighed by the instant bandchange and computer interface.

KR6X comments about the wide filters in the first IF.  Sherwood Engineering
solved that problem with their line of 1st IF filters.

I still have one of my C-lines.  I won't part with it because it was my
"first" one.  I bought the receiver brand new during college in 1977 and it
saw me through my W5 era of operating including my 1978 low power SSB win
in SS from N5DX.  It was the radio I first experimented with the W3RJ AGC
mod, the Sherwood mods and products (including the magic monolithic
tantalum cap to keep the LM383 audio amp stabilized), low-capacitance
transceiving cables, dirty bandswitches, flat 6JB6s and the never-ending
battle to keep the third mixer from going noisy.

Indeed, reliability is what drove me away from the C-lines.  One of the
rites of fall was to open up all of the T4XCs and R4Cs and spray the
bandswitches and filter switches with some magic cleaner that K3LR
found.  This was much less of a problem if you used the radio every day and
switched around the bands.  Certain tubes in the radios needed to be
replaced often, particularly the 6EJ7 mixers.

Furthermore, while the modified C-Lines were outstanding CW radios and very
good on SSB for receive, they sucked as far as a SSB transmitter.  The
transmit ALC was a mess, and interfered with the operation of add-on RF
speech processors so many people simply stuck a shorting plug in the ALC
jack.  Without ALC you had to be VERY careful with the mic gain adjustment
or the radio sounded like junk as KR6X describes.

RF speech processing was problematic too with the C-Lines.  The Magnum Six
speech processor was the elegant solution, but it had a lot of knobs to
adjust.  The DX Engineering processor had the opposite problem - it had too
few adjustments so the drive level to the final was never optimum.

To summarize, here is the K8CC Top Ten List of Things You Need to Know
about C-Lines:

1. For a few $$$, the W3RJ R4C AGC mod will make more improvement in the
receiver than anything else you can do.  Do it first.

2. 1st IF filtering is important.  Go to Sherwood Engineering at
http://www.sherwood-engineering.com/ or INRAD http://www.qth.com/inrad/.

3. Sherwood Engineering has every mod you will ever need for a R4C.

4. R4C serial numbers are important.  You want a radio that has the five
positions for filters (SSB/AM/1.5/.5/.25) vs. four (SSB/AM/CW1/CW2).  This
also gets you the better 6EJ7 mixer.

5. The 1.5 KHz filter is often useful in heavy QRM on SSB, but a pretty
narrow for my tastes.

6. The T4XC mic input is high-Z.  You'll need some sort of impedance
matching for your Heil headset.

7. Keep a stock of 6EJ7 tubes.  If you ever see an ad for a "6EJ7 Sartori
Solid Tube", buy it.

8. Occasionally disconnect the antenna and on 28 MHz try peaking the
preselector control.  If you can't hear the white noise peak, you need new
tubes, realignment, or both.

9. With regard to your transmitted signal, learn what "spotting" is.

10. Install a muffin fan over the final tubes on the T4XC.



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