Ted Bruce wrote in message
news
On Tue, 05 Apr 2005 00:44:57 GMT, "RadioGuy"
wrote:




Hi Ted... I lost myself in this thread... well, that's how it all got
started. I was going through my Drake stuff when I looked at my tube
spares;
sets of 3 matched 6JB6's for the TR-4. The price I paid at AES for each
set
back in the late 70's was marked on the packages---$18.00 and they are
going
for nearly $100 today! My mind wandered to the 6146's and the question
was
born---why didn't Drake use the 6146's instead of those sweep tubes?
Decades back those 6146's seemed to be everywhere. Heck, I had a bunch
that
I was given not to mention what I collected here and there. You are
right,
the matched 6JB6's cost more than the $20 I quoted but I tried to be fair
and compared a single 6DQ6 to a single 6JB6. Looking at what a matched
set
of 6JB6's cost for my TR-4 they seem closer to $30 each (the last time I
checked).

Through the course of conversation I began to feel that Drake used those
tubes to increase their profit margin since they were available nearly
surplus (no longer used in TV designs) at $0.50 apiece (based upon what I
read somewhere). I tried to find the relative quantities produced; 6JB6's
compared to the 6146. I think we ended up somewhere that there were many
more 6146's made than the 6JB6's---so the price... classical economics
rules. If the tubes used in the Drake gear were 6146's, more than likely
they would go for around $10.00 each (I've seen them go for around $6 to
$7). Its interesting to reflect that with all the amateur rigs out there
that used the 6146; from the Ranger I and the KWM-2 (and who knows what
else) maybe ending somewhere with the Kenwood gear of the 80's, the price
of
the 6146 has effectively escaped the price escalation that seems to have
affected the 6JB6.

Anyway, I found some interesting articles on the web; QST (1980) by Doug
DeMaw and in 73 (1975) by a young Dave Ingram (now of CQ magazine). The
articles present design information related to the use of sweep tubes in
rf
power amplifiers. I'm sure the boatanchor group would like reading
through
them, besides, you just can't miss Doug's 2-meter amplifier using two
6JB6'
s!

http://www.thermionic.org/sweep.html

Thanks for the link. Yes. that article on the family of 6146 tubes was
informative.

RG
RG, I'll definitely check out that site. Yeah, it was a mystery to
me. The Japanese radios I knew of , primarily the Yaesu FT-101 that
one of the guys in the K6NCG club station at Treasure Island in San
Francisco bay used sweep tubes, I'm pretty sure the Henry (Trio) rigs
used them; and I don't know about Swan, which was popular then as a
low cost alternative. Yet Heathkit used 6146s in their premier line,
the SB and later, HW-101 rigs.

I have heard stories of sweep tubes melting down under sustained load,
but I have a true story regarding the 6146. When I was stationed at
TI, we lived in Navy-sponsored housing in Oakland. The landlord of
the apartment lived just underneath us on the 1st floor. They agreed
to let me put up one of those Miniproducts half-wave triband
verticals. One day after a QSO I was turning away from the rig and
simultaneously turning the SB-100 off. About 45 minutes later, the
landlady came up and asked if I was on the air, because their tv set
was blanking out constantly. I said that I had been, but I was off
the air now. then I walked over and checked the rig...I hadn't turned
it off 45 minutes earlier, I had switched it to the "Tune" position!
I had been generating full carrier output...as they say, a brick on
the key. Now that's rugged. I finally replaced the tubes with new
6146W's 8 years later, but only because they were given to me by a
friend. I still have the 6146Ws; I'm going to put them in my HW-101
sometime this week, while I have the rig opened up to shift the
carrier point to the center between USB and LSB.

73,
Ted KX4OM

Yea... I had a pair of 6146W's given me too---in the white box with the
black print on the side ;-). That was one of the points of conversation in
the thread, those 6146's and 6146A/B's were everywhere.

Treasure Island... most likely in the 1970's. a few years earlier had me at
Hamilton AFB... I used to hang around at AG6HQ/K6FCT. There is a Microsoft
Groups page 'HamiltonAFBHistory' at
http://groups.msn.com/HamiltonAFBHistory

After the base closed the MARS station became Navy with the call NNN0VNV
http://www.qsl.net/k6bw/

RG