The AM Forum

I sold my HRO-60 in about 1957, and here a half century later, just bought another to go with my restored transmitter. (see www.w8vr.org)

I recall that I had built a product detector for the HRO, that plugged into the NBFM socket, but  I cannot remember where I found the schematic.  Moreover, there may in later years have been additional designs.

Can anybody please point me toward info relevant to a home-brew SSB product detector that will plug into the NBFM adapter socket in an HRO-60?

Thanks -

-al hart, w8vr

It's not gonna just plug in, you need to run the BFO signal to it.   There may have been an aftermarket accessory that included a BFO and just plugged in, I dunno.

I've done this a couple ways using a 6SN7 and the dual triode product detector design in any 60s ARRL handbook.  First, you can rewire the NBFM socket and just plug in a 6SN7.  It's not too harsh.  Second thing was I wired a 6SN7 product detector on one of those Vector assemblies having an octal plug and octal socket.  You need to do a bit of rewiring with the BFO switch - as I recall it's a DPST and you can switch the audio from the AM detector to the product detector while turning on the BFO simultaneously.  Makes a really good mod and not too hard to reverse if you come across a purist you wanna impress.

Thank you, OM.

Al

That's a great photo essay on your rig..  Thanks. I enjoyed it.  Are you going to put up something on your shack and your newly found HRO?

Al VTP

Al, if you have some old QSTs kicking around, check in the 1960-61 years. Pretty sure there's an article in one of them with a product detector similar to what Johnny is describing, in this case for the 75A-2. Should be in the ballpark. IIRC, it swaps the FM position for SSB on the A-2.

I actually have one of those aftermarket units in a 75A-2 parts rig here. They plugged into the NBFM socket and a shaft for the BFO ran through a hole drilled in the front panel where the emblem was removed, with a small knob added. On this one the shaft is gear to another knob elsewhere, with the emblem left in place to cover the hole. Pretty slick set up, never got to try it out.

To Al, W1VTP - Tnx fer the kind words about the rig and its write-up.  Yes, I intend to write a bit more as the rig gets finished and I get it on the air.  I've a little more work to do on the rig, and the HRO I bought is known to be not in working order, so I''ve got to work on that, so it'll be some time yet.  Also, my 80/40 antenna is lying on the ground, I haven't the physical ability to fix it and I haven't yet found anybody to hire to get it back up.  It'll all work out in time!

To Todd, KA1KAQ - I've taken your suggestion, looked back through the QST archives, and found some relevant data.  Thank you.  I also am aware of a crystal filter detector that was used, and I'm still looking for that one.  I appreciate your idea.

Haven't been out to the other garage to check the parts rig, but it came to me that the aftermarket version was made by a company called Universal, if that rings a bell. Copper-clad box with an octal plug, designed for the NBFM socket in rigs of the day I guess.

I'll get some verification over the weekend. They do show up for sale occasionally, but mainly show up included in an old receiver. It's actually a pretty clever product.

The last run of 60's in 1968, which were all for Tropical Radio, had a built in product detector and a Collins mechanical filter for either CW or RTTY. Unfortunately I had no interest at the time and never obtained the circuit. I did do the installation down in Weymouth. Others were sent to Central and South America to the United Fruit plantations and shipping offices.

An easy way is to use a CE B Signal Slicer which also includes a Q Multiplier. The manual includes hook up info for the NBFM socket. Ive been using several on different radios and they do well.

Carl

What about something like this? Clark uses one and said it works great.

http://www.ebay.com/itm/190528540754?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649 (http://www.ebay.com/itm/190528540754?ssPageName=STRK:MESINDXX:IT&_trksid=p3984.m1436.l2649)

Those bypass the radios audio section and require either an amplified PC speaker or an external preamp/amp.

I dont see any distortion or signal handling specs either.

+1 on the Central Electronics slicer.  That's a Fine Business piece of gear and one of the best sounding "SSB adapters" ever.  It also does a great job of rejcting the opposite sideband due to the I/Q demodulation and phase shifter (like a phasing SSB exciter in reverse).  Mine has a good 45 dB of opposite sideband rejection, and the Q-mult is good for notching out carrier heterodynes.

Todd,

It was made by Universal Service Co. of Columbus OH.  I picked up a parts unit that came with one.

http://www.universal-radio.com/location.html (http://www.universal-radio.com/location.html)

(http://www.universal-radio.com/images/thirdst.jpg)

Interesting! That's the one, Rodger. Neat to see the old store front for the original biz.

I've got a CE Slicer B that I'm itching to lash up to something. Heard nothing but good things about them over the years.

Yep. I used it on an SP600 and on an R390. Just feed in 455KC.  Then you can route the audio back into the RXer like the CE slicer or you can just run external audio. I use an old Tube amp called "the voice of music" to an R46 speaker.  The audio is clearer and better sounding then the Icom 756 pro on SSB.  SNR is fantastic. The SX28A has alot of drift. But the other rigs are pretty stable.

On the HRO its simple hook up of SSB adapter.

Run RG58 into back cabinet through vent. Pull tube. Hook to correct pin to get 455kc signal. Adapter has cap already in circiut. Run audio output of SSB adapter to PHONO jack on HRO.

To run SSB, FLip HRO to PHONO postion and you have great SSB!

I have both versions of the CE and I have a BW SSB adapter.  Sure they look neat but then you have two sources of drift. The Converter and the RXer. With the little modern adapter its rock solid so I think it works better.


C