[GreenKeys] CV-89

[Jim Sheldon]

I too used the CV-89 in the MARS RTTY net when I was stationed in 
Northern Japan from 1963 to 1966.  The main thing I remember about it 
was it was really great on 850 Hz shift, pretty good on 425 Hz, but when 
the standard started to become 170 Hz shift, at least the A model CV-89 
we had was somewhat temperamental in holding it's tuning.  We never saw 
a B model so I'm not sure how one of those will copy 170 shift.  It 
wasn't a case of the RX drifting as all we ever used were Collins 
R-390A's on the receiver side.  We did have a couple of Hammarlund 
SP-600's in the rack, but they were too unstable for anything but 
listening to AM broadcast and international short wave audio even if you 
left them turned on all the time.

We also had a Boehme-5C tuneable audio converter (huge boat anchor) that 
was primarily designed for 850 to 1000 Hz shift and had a BIG tunable 
inductor to set the shift.  At maximum inductance, we could copy 170 Hz 
shift reliably with it and it had a built in loop supply whereas the 
CV-89 did not.  We actually had them set up so the 5C's loop supply 
passed through the CV-89 as well and that worked OK as long as we didn't 
try to have both of them hooked to the receiver(s) at the same time - 
LOL!

I actually wound up getting to keep the Boehme when I rotated back to 
the States in late 1966 along with a really pristine Model 19 and Model 
14.  Sure wish I had kept them, but my wife is glad I didn't, especially 
after I wound up with a huge oil streak up the shack wall when I was 
doing PM on the Model 19.  I had poured about half a can of 30 weight 
Pennzoil on the felt clutches and started it up - forgot to set the loop 
supply on and it ran open with the cover off long enough to sling most 
of that 30 weight right up the wall behind the machine.  Good thing we 
had good paint as it did clean up okay.  Learned my lesson after that 
and did all the PM outside or in the garage.  Once personal computers 
arrived and RTTY to ASCII conversion programs became available, I gave 
the machines back to the MARS program.

I did pick up an absolutely brand new HAL ST-8000A that was still in an 
unopened HAL shipping container and currently use it as my primary T/U 
with MMTTY as secondary.  We were just getting the ST-8000's in the 
intelligence monitoring community when I retired from the Army Security 
Agency in 1981 so I was familiar with it and even though I paid too much 
for it, HAL was very helpful in getting me the info and parts I needed 
to change the MIL plugs on it to DE9's.  Their DSRTTY-WIN program is 
still available and I use that with the 8000A to run RTTY and ASCII with 
it.

Jim Sheldon - W0EB
Park City, KS
------ Original Message ------
From: "Linger, Michael I" <mlinger at civil.tamu.edu>
To: "'GreenKeys at mailman.qth.net'" <GreenKeys at mailman.qth.net>
Sent: 10/21/2015 11:14:49 AM
Subject: [GreenKeys] CV-89

>I used the CV-89 converters for several years in the military as well 
>as it was my only converter in ham use in the ‘70’s while in Navy MARS. 
>  I had no troubles at all in the military with them and rarely any 
>trouble with my own units while in MARS, which I used several times a 
>week for RTTY net operations.  I still have several of them and really 
>like them.  These units were designed to operate with a rather large 
>fan unit on the back of them, mainly because they were to be used with 
>their brothers (another CV-89 and a CM-22 comparator unit), all stacked 
>in a rack that runs pretty hot when all turned on.  However, I used my 
>CV-89 units without the fan and by themselves and found they ran with 
>no issues.  I also ran my CV-89(B version) with an outboard simple 3 
>stage op-amp 741 input limiter at the audio input which enhanced the 
>performance significantly.   The only tubes I ever replaced were the 
>6x4 rectifier tube, which runs hot regardless of where it is, and 
>occasionally I replaced the 6AQ5 tubes in the keyer circuit.  All the 
>tubes in this unit are available on ebay for cheap, as well as all over 
>the internet at various sites.   Over my 52 years in amateur radio I 
>think I’ve had nearly every kind of TU they’ve made in the past, 
>including the ST-8000, ST-8000A, Flesher, DT-600, Heathk 3030, URA-17, 
>CV-116, etc., and all the ST Hal units and all I’ve kept is my trusty 
>CV-89B’s, the ST-6, and my Dovetron MPC-1000CR.  That said, I have to 
>say it’s pretty hard to argue with the High-Tech equipment we have 
>today for data communications.  So ask yourself what you want to have 
>fun with and go from there.  If it’s the old vintage stuff, don’t be 
>afraid to acquire and play with it to make it work for you because 
>you’ll learn allot and move on.  If the old stuff is what you like you 
>wouldn’t be on this forum asking about archaic things like Teletype!
>
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