The AM Forum

Member Vincent posted a link to the TMC manual repository here:  http://amfone.net/Amforum/index.php?topic=26791.0

I downloaded the manual for the RF section of the DDR-5.  Now THAT is one impressive RF section.  4 stages of RF, a 417A tube as the first stage cascode coupled to a 6AH6... and a Vackar LO.

A really impressive front-end! All those coils mounted on a turret! Photos show an excellent mechanical construction (typical of TMC). Four RF amplifiers give a very good sensitivity (especially with a 417A as the first amplifier) and excellent RF selectivity, but I have a doubt about the behavior of the "modest" 6S4A triode mixer...

I just noticed in the diagram that the signal is attenuated by capacitive attenuators in every single RF filter (except, of course, the first) and then the signal that arrives at the mixer is much lower than you can imagine when you first take a look at the schematic. So high selectivity but low amplification. Good trick!

Yeah, and there's a dual 6BE6 Lamb noise silencer in the thing too!

I had one of those, and stupidly sold it (I had just the RF section and synthesizer).  As I recall mine had a motorized tuning that synchronized with the synthesizer, which is different from the one in that manual.  I don't recall that it had that many tubes either - but it looked the same from the outside.

I knew I wasn't dreaming - this one has the motorized tuning.  The whole radio could be controlled by 5-level teletype!  Amazing, for 1967.  Could it be the first use of an integrated circuit in a radio?  See page from manual below.

http://www.virhistory.com/tmc/tmc_pages/tmc_manuals/manuals_db/ddr-5/tm_ddr-5br-5br1_1_15_67.pdf

TechniMatiC! Awesome.

Sounds like a nice preselector for HPSDR

It would have been a nice hi-fi RX for AM or SSB. The 15 kc IF filter was the most broad for AM use and it had USB and LSB filters as wide as 7.5 kc. The audio amp was specified at 20 cps to 20 kcps! Nice.

With the AFC it would also act as a sync detector - the AFC-3 module specs say it would lock on a carrier -30dB down from the sidebands.  Add to that the dual-diversity, and synthesized or free-funning VFO tuning and you have most likely one of the finest-business receivers ever made.

Hi John,

Obviously a far cry from the poor design and very mediocre performance of the now-collectible TMC GPR-90 and the GPR-92. These two receivers are nice eye candy, but for my money, that's about it.

I was never aware that the DDR-5 was such a well-designed receiver unit, much less with a WE-417A in the front end. For that matter, I am not aware of any other HF receiver that used the 417A, as the tube was really designed for VHF & UHF low-noise amplification. I have seen DDR-5s in the past, most recently back in December, but the receiver was sitting on a shelf and was not integrated into the fellow's station at the time, so there was no opportunity to take it for a ride. I'm wondering if the DDR-5 was designed by Murray Gellman, K2CBO; he was the the engineer at TMC who was responsible for most of their receiver design work (including the less-than-stellar performing GPR-92) during the early to mid-1960s.

I think the DDR-5 may have been designed to fulfill a need within the TMC product offering for a very high performance receiver capable of being used for diversity reception applications: DDR=Dual Diversity Receiver. The GPR-90 and the GPR-92 were sold as part of earlier-generation TMC systems requiring diversity reception, and the GPR-92 had the advantage of being able to operate from a common, external HFO, such as the TMC VOX or PMO series. The GPR-90 did not have this capability. Very early TMC diversity reception systems used TMC-modified Hammarlund Super-Pros, but once the GPR-90 came out in 1955, that was all they used going forward, until the later generation receivers such as the GPR-92, etc., were introduced.

TMC also made a model GPR-110; I believe this was an all solid-state design, but I cannot swear to it, and I'm not at all familiar with this unit, other than seeing it in some of the TMC sales literature.

73,

Bruce

Technical Bulletin for the DDR-5 Receiver

........

FWIW, My DDR-5 (AN/FRR-60) restoration project photos are on-line. It is one nifty rig :-)
 http://www.navy-radio.com/rcvrs/frr60-2.htm
cheers,
Nick K4NYW

Hi Nick! Not many receivers need to be off loaded with a fork lift!

Moar pics of that beast and its components, Nick!  Also how about a little writeup on your view of its performance, etc.

Weren't you the guy that bought a couple of lime-green DDR-5 components from me at Dayton one year?

Is that the one that came out of George's basement, Nick?

Definitely a cool looking rig with the Nixie display. Any chance of taking for a spin when I bring those manuals down?  ;D

Nick

  Words cannot describe my jealousy  :-X That is just way too cool !!

 In the early 1980's I got one of these monsters. I had all except for the synthesizer and the cabling. Without cables I gave it up, and another ham last I heard got the RF deck working. It was just too big!

Jim
WD5JKO

I had a look up close at a FRR-60 receiver at a local electronics surplus place a couple of years ago, and it was one impressive looking 2 large rack unit receiver. It would be interesting to find out just how well they perform. I was tempted to buy it.

I own and use a TMC GPR-92. The receiver is far from perfect. I find it to be sensitive and stable, but I found the selectivity and AGC action to be poor even after aligning the IFs with a sweep generator. The receiver is what is is, but I wasnted to see if I could make it work better for me.

I'm using a digital frequency readout and a Kiwa MAP AM synch detector with the receiver now. The MAP has two selectivity positions 6.9 and 2.9 kc. from a combination of cascaded Kiwa ceramic filters and AF filtering. The ceramic filters seem to have excellent shape factors from my use. The MAP has its own AGC circuitry, and the adjustable high pass filtering can be used as a AF notch filter if you need it. I know its another add on box for the receiver, but it makes the 92 work great for me.


Al VE3AJM

My TMC RCAF FRR-5007 actually uses the WE 417A tube in many of the plug in modules for the RF amp tube Bruce.

Al VE3AJM

Man, I thought the 250 lb. FRR-59B that I had was huge.

It was a lightweight portable compared to your DDR-5.