National HRO50

[KE7KPB]

Dumb question for the day.
After I overhauled my HRO50, the radio plays great and receives stations that any modern radio could not even think of picking up but WHAT do I need to do to tune in sideband or it something beyond the capabilities of the radio ?

[Ralph W3GL]

Assuming you have no idea of what CW is (relatively new general light licensee),
it uses the "Beat Frequency Oscillator" other wise labeled "BFO" on the front panel
of the receiver to make the generated make/break keyed carrier of the transmitted
signal produce a tone to enable easier copying the code...

Activate it  and play with it as you tune across the SSB signal and there you are...

SSSB (single sideband, suppressed carrier) needs a carrier reinserted on the same
frequency as the original suppressed carrier (the bfo signal) to have the audio demodulated by the receivers detector.

Beyond the capability's of the radio? Come on, use your head, THINK ...

[Pete, WA2CWA]

SSB Product Detectors for the HRO:
QST 1964, page 47
QST 1968, page 20 (solid-state version)
A Google for "product detectors for HRO" turned up a number of hits.

I seriously doubt this statement is true: "...and receives stations that any modern radio could not even think of picking up"

[w3jn]

As Ralph so delicately put it  the HRO-60 certainly can receive SSB.  The BFO injection isn't all that strong so you need to reduce RF gain in most cases so as to reduce the distortion, since the BFO injection needs to be stronger than the SSB signal you're trying to copy.

Turn on the BFO, tune in a SSB signal, then reduce the RF gain a bit.  Adjust the BFO and/or tuning to clarify the signal.

An easy and reversible modification to make this a little less painful is to parallel C-125, the BFO injection capacitor with one that's about 20-50pF.  This will increase BFO injection greatly, at the expense of activating the AVC (and thus reducing receiver sensitvity) with the BFO on.

Alternatively you could build up a product detector that plugs into the FM accessory socket.  I've done that on a HRO-60 and a NC-183 variant (the NBS-1) and it works well.   

[WQ9E]

JN covered the subject well and if you don't want to build up an internal product detector keep an eye out for a Central Electronics "Sideband Slicer".   This is a phasing type external SSB adapter that works well and looks great with vintage gear.  They go for $25 to $45 at hamfests (at the higher price they generally have the optional Q multiplier, which somewhat improves selectivity, built in).  They are easy to hook up and the manual has specific instructions for the popular vintage receivers. 

Other vintage external options include the RME-4301 (also phasing type) which is considerably more expensive since it matches the 4300/4350 receivers and the excellent Hammarlund HC-10 which is essentially the final IF, AGC, detector, and audio system out of a HQ-170.

But for occasional usage on SSB the reduced RF gain method works fine.

[The Slab Bacon]

As Ralph so delicately put it 

I definately have to agree with Ralphie on that one. Definately left me with a chuckle  

[KM1H]

The CE A Slicer had just the product detector, the B Slicer included the Q Multiplier which is a nice addition. Im up to 3 B Slicers here, a pair of HC-1's and a RME something or other. A gutted National NBFM module with a PD is used in the 60 which would also work in several other Nationals.

Carl

[KE7KPB]

Assuming you have no idea of what CW is (relatively new general light licensee),
Ralphie, My O My assume, well you made the first part very well. I started in Radio in 1965, first station was a
ART13, Dynomotor on 2 truck batteries with a Bc receiver and a brass key which I still have but deep in mothballs.
I work on Antique radios from the chassis to the wood so when I get done they are like new and I still think they are something to be treasured. I was watching on Youtube about a HRO 50 not a sixty and the ssb was coming through quite well and not sounding like you are trying to make a AM rig tune to ssb.
I can't stand Argonaut people as there are always someone out there that is better.
A man one to me that he was  irreplaceable and I said yep, grave yards are full of irreplaceable people..
I am an mechanical engineer by trade and just getting back into radio at least the transmitting side after a very long time off. As they say on Warner Bros. That's all folks.

 

[w3jn]

Agree on the CE Signal Slicers.  One of the best sounding outboard product detectors around, and it has outstanding opposite-sideband rejection when aligned properly.

[Rob K2CU]

The usual procedure with radios of this type is to operate them as follows for CW/SSB:

Turn down RF/IF gain control.
Turn off AVC/AGC.
Turn up audio volume near max.
Turn on BFO (CW mode)
Start with widest selectivity.

Use RF/IF gain to control level of received audio.
Adjust BFO frequency to be at one end of pass-band, high or low. You will have to experiment with this for SSB as the signal may flip from one sideband to the other by the conversion process(s) from RF to IF and may also by which band you are on.
You can start with the BFO in the middle position and then see which direction to move it and still receive the signal. BY moving to one end, you will reduce adjacent (channel) QRM, as the undesired frequencies will be down the skirt of the filter.

You might experiment with selectivity settings for best performance.

This same method can be used for exhaulted carrier AM reception.

[ke7trp]

You can learn to use the BFO but its never as good a product detector.  ESP makes a nice Product detector that you can plug into the NFM socket on the HRO 50/60 receiver.  No mods at all.  You then switch the radio into the NFM and you get outstanding SSB.  You will need a spare octal socket that fits the NFM socket.  Its 3 wires.  Very easy.

Here is a video of the product detector on my HRO60.  I dont know the guy and do not benifit if you buy one. I found them advertising in electric radio.

http://youtu.be/6BHMxRZeusk

http://youtu.be/8fQJqDaa-XI

C