No hurry. I have been known to take all the pieces of a project and put them in a labeled box so they don't go wandering off..... I owe you a sketch of how to get that 9 volts for the audio filter anyway. 73 de Jim, N2EY
GE looked this type of receiver in 1962-63 Ham News publications with their Compactrons ..... by Norman L. Morgan, W7KCS/9 November/December 1962 http://w5jgv.com/downloads/GE Ham News Nov-Dec 1962.pdf Spring 1963 http://w5jgv.com/downloads/GE Ham News Spring 1963.pdf
Most interesting! In particular, the first mixer uses the Pullen circuit, though it is not identified as such. The product detector is a 6JH8 beam-deflection tube, similar to the 7360 but lower-priced and more available. 73 de Jim, N2EY
Good eye, Jim. Mr. Morgan described "The first mixer stage uses a rather unusual cathode-coupled circuit." In the footnotes of the receiver article, Keats Pullen's book is referenced ! A Cathode-Coupled Triode Mixer (Pullen Mixer) excerpt from his book, Conductance Design of Active Circuits, John F. Rider Publisher, 1969. by Dr. Keats Pullen http://www.w7ekb.com/glowbugs/rx/Pullen/PullenMixer.pdf A Like New Mixer Circuit 73 Magazine, October 1961 http://www.w7ekb.com/glowbugs/rx/Pullen/A Like-New Mixer Circuit.pdf Another Look at the Like New Circuit A low distortion low noise mixer 73 Magazine, August 1966 http://www.w7ekb.com/glowbugs/rx/Pullen/AnotherLook.pdf Pullen Mixer from the RSGB “Radio Communications Handbook”, 4th Edition, 1972. Uses the 6AQ8/ECC85 vacuum tube http://www.w7ekb.com/glowbugs/rx/Pullen/Pullen Mixer from RSGB.pdf -- w9gb
Haha! Clever "bump" via the other thread I did finally get most everything sorted out on the HR-10b and it works well on 40 and 20. But still dead on 80 due to that broken antenna input coil I mentioned a month or so ago in another thread. This project has taken a back burner for right now, with all the move and everything. But by Fall it will be paired with the DX-60b and HG-10b for sliding into winter time again, with [hopefully] all new antennas by then. I'll post up pix of the "Novice Corner: Heathkit Edition" soon - it looks pretty cool, and I even have the QSL card designed for it! See below... Dave W7UUU
Niiiice! My rigs are quietly awaiting attention. The L-4B and SA2060 rebuilds both got in the way. Are you going to do any AM work with the '60?
Dave - The happen to be looking at the Hallicrafters SX-122 schematic diagram. The SX-122 is a dual-conversion receiver, the two intermediate frequency (IF) stages at 1650 kHz and 50 kHz. Page 1 (schematic) https://3f42eef8-a-62cb3a1a-s-sites.googlegroups.com/site/roveroresearch/home/boatanchor-radios/sx122/schem122_1.gif Page 2 (schematic) https://3f42eef8-a-62cb3a1a-s-sites.googlegroups.com/site/roveroresearch/home/boatanchor-radios/sx122/schem122_2.gif The Heathkit HR-10(b) used a single IF stage at 1681 kHz.
Im a big Pullen fan and have converted several BA's to them and never disappointed. With a low noise mixer that radio might wake up on 20 but it will not be an easy job. Ive used 6SN7, 6J6, 12AT7, and 6ES8's. Modded my 75A4 to 7360's in both IF's before the Pullen appeared. With only 125VDC on most of the HR-10 a bit of a gain boost might help 20 and up. Try a 6GM6 in the RF amp and reverse wires to pins 2 and 7 and see what happens and then drop the cathode resistor to 56 Ohms to do the tube justice at that voltage. Try the 6BZ6 in the first IF with the same pin swaps. With some changes the SX-140 makes a nice AM and fair CW radio but not for the novice modder. I turned both of mine into double conversion with 262 and 455 IF's and other mods. Used one at a time at our summer place in Maine along with a modded T-150A....space was at a premium. Kids grew up, rigs and cottage sold. Carl
See post #39 for some ideas about dual conversion. The SX-140 kit cost $20 more than the HR-10 kit - $80 vs $100. A lot of money in 1962!
After re-reading Post #39, and doing some thinking, here's what I'd do: 1) To improve the performance on the higher bands, I'd build a simple crystal-controlled converter. Two tubes at most - one for the crystal oscillator, one for the mixer. A 6ES8 dual triode in the Pullen configuration could do the job well: http://www.rlinwood.com/family_webp...nt/collins_75a4/75a4_Docs_Mods/75A4Pullen.pdf Such a converter could add WARC band and WWV reception - just a matter of finding the crystals. With a single 3500 kc. crystal, 20 and 15 can be covered by using an overtone circuit (there's a QST converter that does this.) Using a converter with the receiver on 80 means the stability of the HR-10 on its best band is preserved. If the 6BJ7 triple diode and the 6X4 rectifier are solid-stated, the HR-10 should be able to power the converter easily. 2) Add a VR-tube or Zener diode regulator for the HFO and BFO. 3) If one can find crystals on or near 1681 kHz, modern ladder filters can be made which will improve selectivity greatly. They can be switched by small DIP relays. A subchassis with the filters and relays can be made that will fit in the space vacated by the first IF transformer and the crystals, so the receiver can be restored to original condition if desired. 4) Audio selectivity can be added as an alternative or in conjunction with improving the IF selectivity. 73 de Jim N2EY
