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NZ9Y
01-13-2012, 05:20 PM
I'm trying to put a 32V-2 and 75A-2 together and get them on the air. I dont have a ton of experience here and I dont want to kill my receiver!


I have a Dow-Key 110vac relay (with UHF type connectors) that came with this pair of TX/RX and I dont quite understand it. I wan to make sure it works properly. I understand the function is to switch the antenna from the RX to the TX. I would thought that at rest, 1.) the center conductor would have continuity between at least two connectors. 2.) at least one end would be "shorted" at rest to protect the receiver.

I know how to activate the receive muting, but I dont get how to ground the RX antenna connector to protect it from the TX.

On a side note, I can't BELIEVE there's no way to reduce the output on this transmitter! I'll bet a lot of RX front ends were killed back in the day by simple mistakes. I have the original manuals and I have to tell you, I find todays "translated to english" manuals to be much easier to understand. Man, I need an Elmer here.

WB2WIK
01-13-2012, 05:30 PM
I have a Dow-Key 110vac relay (with UHF type connectors) that came with this pair of TX/RX and I dont quite understand it. I wan to make sure it works properly. I understand the function is to switch the antenna from the RX to the TX. I would thought that at rest, 1.) the center conductor would have continuity between at least two connectors.

Yes, it should, unless something's wrong with it. There is continuity between the center conductors of the "antenna" port (the UHF receptacle at the "end" of the relay) and the "RX" or "normally closed" port, which is the port on the same side of the relay as the coil is located. At rest, those two should have electrical continuity.


2.) at least one end would be "shorted" at rest to protect the receiver.

No, not at all, and not necessary. At rest, the two as described above are connected. When the relay is activated, the common "antenna" port (end of the relay housing) should switch to connect to the "TX" (normally open) port, which is on the side of the relay that does not have the coil.

A properly working Dow Key DK60 has tremendous isolation between the TX and RX ports when it's activated; enough to run 1kW AM power (4000W PEP) with a sensitive receiver, without damage. Remember also the 75A2 uses a tube front end (and everything else) and can easily handle several volts of RF at its input (much more than many modern solid state rigs could handle) without risk of damage.

NZ9Y
01-13-2012, 05:47 PM
Thanks Steve,

I actually just now found the 2 "receive" connectors. I had a bad test lead on my meter! I'm glad it was that instead of the relay.

I have no idea what model this Dow-Key is, but its old as dirt, dark grey crinkle finish that matches the rigs and is about 3 inches long excluding connectors. It says "Dow-Key Co, Inc" and 110vac.

God Bless whoever took this setup out of service, they left most of the connecting wires attached. I'm concerned that I'm either not understanding something in the manual or there is a type-o. (Mimeograph-o). For the receiver muting function, the receiver manual says connect receiver terminals M and G to the transmitter terminals 15 and 12. The transmitter manual says when using a 75A receiver connect transmitter terminals 15 and 12 to receiver terminals "B" and G. There is no erceiver terminal B.

Since the 32V-2 transmitter is a couple years older than the 75A-2 receiver, I'm hoping there was a change. :confused:

NZ9Y
01-13-2012, 06:11 PM
By the way Steve, Your explaination above makes perfect sense to me. I really appreciate you taking the time.

This new, middle-aged post-code ham is finding the learning curve of obsolete technology pretty steep on my quest to be more than an appliance operator. :p

Learning to operate these cool old rigs is a BIG part of why I became a ham in the first place. I love my modern station and use everything its capable of. There's just something romantic about the look, sound and smell of a vintage all tube station.

I'm terrified of killing these amazing rigs, but I guess I just have to do the best I can and at some point throw the HV switch and pay for my mistakes.

KB4QAA
01-13-2012, 09:18 PM
http://bama.edebris.com/download/dowkey/dk60g/dowkey.gif

Dow-Key DK60 Instruction Sheet from Bama Mirror

NZ9Y
01-13-2012, 09:57 PM
Thats the one. I got it figured out, but I sure am saving that .gif.

On to the next problem. No HV. I'm not sure where to start (fuse is good). I was hoping to be on to the "choosing the best sounding microphone" stage by now. Oh well, at least the 75A-2 receiver works. That should keep me occupied while I research the TX. I'm suprised at how little repair and service discussion is out there on the net.

K9STH
01-13-2012, 10:52 PM
Unfortunately, the Collins 32V- series has a pretty weak transformer in the fact that the 5.0 volt filament windings for the rectifier tubes often "short out" to other windings. The 32V- series, along with Hallicrafters HT-32- series and the HT-37, are among the very few that I definitely recommend removing the tube rectifiers and gong to solid-state. Then remove the 5.0 volt connections. Remember, the B+ is carried on the rectifier filaments in those transmitters (and on most others as well).

Also, watch out for the filter choke developing a short to the core.

You can get the choke and transformer rewound. However, rewinding is not inexpensive!

Glen, K9STH

KM1H
01-14-2012, 02:23 AM
The original Dow-Key did not have sufficient isolation above 40M to protect receivers when power was run. They came out with a replacement receive side connector that had a spring loaded sliding contact to add a lot more isolation. Later D-K's could be bought either way.

Everything is weak in the 32V family, the mod iron, driver, and LV xfmr all go unexpectedly as well as the HV parts as mentioned. After its working fix the audio so it doesnt sound like space shuttle audio...thanks to the ARRL's campaign to destroy AM in the 50's by limiting it to SSB bandwidth per sideband.

Carl

K9STH
01-14-2012, 04:28 AM
I have a 32V-2 that I acquired as a "project" several years ago. I haven't gotten around to working on it! Also, have a 32V-2 in for repair that has a number of problems. Am working on that a little at a time to keep down what I have to bill the client.

At least you don't have to remove 144 screws to work on the 32V- series like have to be removed to get at all stages in the Hallicrafters HT-20! I have an HT-20 (s/n 11) and dread if I have to work on it! There are shields under shields in that transmitter.

Glen, K9STH

KM1H
01-15-2012, 02:22 AM
The 32V3 is almost as bad; Im not afraid to bill by the hour to Collins collectors who drive up in a new Navigator and similarhttp://files.qrz.com/static/images/smilies/cool.png They would be insulted if the full restoration cost only what it did when new.

Carl

WB2WIK
01-15-2012, 02:30 AM
I have a 32V-2 that I acquired as a "project" several years ago. I haven't gotten around to working on it! Also, have a 32V-2 in for repair that has a number of problems. Am working on that a little at a time to keep down what I have to bill the client.

At least you don't have to remove 144 screws to work on the 32V- series like have to be removed to get at all stages in the Hallicrafters HT-20! I have an HT-20 (s/n 11) and dread if I have to work on it! There are shields under shields in that transmitter.

Glen, K9STH

Don't you hate that? Probably attributed to that new "television" phenomenon that was occurring around then...and TVs with 21 MHz IFs.

I like that I can currently operate anything I have with all the covers removed and there's no such thing as TVI anymore.

What a relief.

I've never seen at HT-20 but if I had one I'd probably put in about every tenth screw.

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