Then thank goodness you no longer have it. it has been saved.

Out of the 30 Hammarlund HQ-100, 110, 145, 170 radios I have owned I did not have a single one that was completely free of the mica sandwiches. I believe if Hammarlund had continued to produce them they would have fixed all their mistakes. The later models as well as the -A types were much better units. They are still good working radios. I have solid stated all of the above mentioned models and eliminated all the problems associated with tubes. The last remaining problems cannot be changed such as the variable capacitor tuning, the temperature sensitive tank circuit capacitors and the wafer switches. The solid state info is available to anyone who wishes to contact me.

In a search for the Silver Mica disease problem, I again found this video. I'm considering the purchase of a HQ-180A as I've wanted one for a very long time. Charles Smith, thank you so much for this information and I hope you are still healthy and active in your electronics repair pursuits. This though is a PITA and requires much patience.😅😁

Frank Koslowski ABSOLUTELY!!!

I started this project because I believed it could be done successfully. Many people said it could not be done. I have successfully converted Hammarlund HQ-100, 110, 145, 170 and Hallicrafters S-85, SX-99, SX-100 models. They perform equal or better than the tube equivalent. I think it makes a better radio but I would not do it to a museum piece. They look the same, work the same and calibrate the same. The advantage is that there is less weight, heat, hum and power consumption. There is no high voltage to kill you and no hot tubes to burn your fingers. There are no tubes to burn out, weaken or short. The only drawback is that there is a lot of wiring modification and a power supply board and audio board must be added. Only an experienced tech will be able to do a modification. You must have tools, soldering equipment, scope, signal generator, frequency counter etc. in order to complete a project. There are a few drawbacks. Strong signals are more difficult to handle. "IF" images are stronger. Some linearity is lost in the S-Meter. Drift is about the same in both models because it comes mainly from the oscillator capacitors which are extremely sensitive to temperature. I will be glad to provide documentation to anyone who wants it for a printing and postage fee of $15.00. I can be found on the Ham call lookup as KV4JT. E-Mail me at [email protected]. My old Juno email is being deleted.

That's FERRULE not FERULE. When I worked for Johnson Controls we used a a piece that is almost identical and it was called a ferrule. It was inserted into a plastic tube to keep it from collapsing when making a connector. A ferrule is generally used for strengthening a joint and an eyelet is generally used for fastening and leaving a through hole. The shapes are identical as purchased but may be applied differently. I guess it's up to the beholder as to which is the preferred term. I'm glad you took the time to watch the video. As for the jeweler's saw, I don't believe many people have one but if you do I'm sure it will work. There are two different thicknesses of the Dremmel cut off wheel. The thinner one works OK and leaves plenty of metal to bend over for securing the "eyelet". Thanks for the suggestion.

Look for Hammarlund HQ170A Sideband Selectivity Switches and click on my name and you will see three more videos.

I really should make more videos to show the solid state conversion procedure for Hammarlund and Hallicrafters receivers in more detail but I have put it on the back burner for now. My next video will be for an amplified RF probe for use with self powered computer speakers. There seems to be a real need for it. I'll post it very soon. My videos have gotten placed in two groups on youtube so I don't know which group it will land in. My fault, I guess, but I don't know how to fix it. Thanks for watching.

There is a patch of silver on both sides of each mica leaf. Simply place your LCR meter probes on each side of the mica leaf and make contact with the opposing silver patches. You will have two sets of capacitors on each sheet in this particular transformer. Write the reading down on your diagram so you won't forget it. Some models of Hammarlund radios use doubled mica sheets in the IF transformers and the value must be doubled. It was done by stacking extra mica sheets and adding more fingers to hold them.

thanks Charles that would make a good short video I have not seen a video talking about that I have seen some talk about remove the wires off the transformers and then testing the mica

I'm assuming you have removed the mica leaves from the transformer in order to read them with your LCR meter. You can't test them without removing them. You should always remove them and replace them with external capacitors. They will cause trouble sooner or later. I get rid of all of them in my radios even if they have not yet failed. See video "Hammarlund HQ-100 HQ-110 HQ-145 HQ-170 IF repair" for more details.

Sorry, I don't know what type of IF caps there are in the SX-71. However, take one apart and look. If there is mica sandwiched in the bottom of the IF then you would be well advised to dig it out and replace it with external capacitors. If they are discreet capacitors then you should be good to go. The discreet ones don't usually cause problems but be aware that any capacitor can short, leak, open or become noisy. Hope this helps.

I think it is litz wire. I have broken the wire before and it is a pain to work with. You can destroy the IF coil if you are not extremely careful. Another thing I should mention is that sometimes you will encounter shorts across the mica leaf and it will bleed high voltage over to the grid of the next tube. When that happens the radio will sound very crappy and you may become confused about what is happening. That's another reason to go ahead and fix them anyway and eliminate any chance of failure caused by the micas. Never install the replacement caps inside the can. Always attach the new caps outside the can so you can easily change the cap and adjust its value if needed. There have been times that the original value needed to be tweaked to make the IF resonate away from the travel extreme of the core adjustment. I am using 50v or 100v miniature ceramic caps for replacements. Since they are across the coil the voltage should never be too much for them. I haven't had any failures yet.

I think you mean "SLUGS"...

+Charles Smith I only RECENTLY found out what was the idea behind "litz" wire- it was to improve high-frequency response by reducing "skin effect".

You probably have a bad oscillator tube or mixer. The IF problem will result in low signal throughout or no signal at all. It is best to fix all the IF transformers anyway because they will give you a problem sooner or later if not already doing so.

+Charles Smith I was reading an old radio repair book, and it mentioned that an oscillator tube can test "good" in a tube tester, but it might NOT oscillate over ALL the frequencies that it is supposed to...this is a particular problem with the "pentagrid converter" type tubes- that combine the oscillator and mixer in the same vacuum tube. With this kind of problem, it is best try substituting another tube.

This radio is very sensitive and will work well on a short antenna but if you want maximum reception on ham bands you should use a resonant antenna for that band. However a long wire of any kind will work for general purposes. An attic antenna should work just fine.

Charles Smith Thanks.

The sandwiched mica caps can't short unless contaminants have entered into the transformer. The most common problem is that they are making poor contact (bad design) or are intermittent. The symptom is the fading of the signal at random or when the legs of the transformer are wiggled with a plastic probe. It is a very good idea to replace them anyway to avoid surprises. They can drive you crazy. This will save a lot of hair pulling. When you remove the mica you can measure it with a LCR meter to get the value. If there are multiple leaves then some of the values may actually be doubled by the way they are connected between the metal contacts. If I can't determine the value then I set the slug at an approximate position and use a variable capacitor to arrive at the peak and then measure the capacitor with my LCR meter. Then select a permanent capacitor that closely matches it and solder it to the legs outside of the transformer (not inside). Use an engraver and make an easily visible note on the side of the can, "caps removed".

There are two videos posted that show how to remove and replace the sandwiched mica capacitors in the HQ-170. There are two types of transformers. Click on my name Charles Smith and it will take you to all my videos. Be sure to watch both before attempting to repair an IF transformer.