Hammarlund HQ-170 IF T1 T2

[@VanWarren]

great work and excellent detailed instructions. Thanks for posting this and preserving these great radios.

[@wa4aos]

Very informative. Thanks for sharing your technique.

[@wa4aos]

Hi Charles, Wondering if you have more Hammarlund videos coming soon; the others have been very helpful.. 73, Glenn WA4AOS

[@charlessmith833]

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.

[@clifffiftytwo]

Ha! Just bought an inoperative HQ-170 on EBay. Thank you for the work in sharing this via video. When the mica cap goes bad, does it short or open or change value?

[@charlessmith7923]

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".

[@charlessmith7923]

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.

[@Kennynva]

So are the mica caps in Hallicrafters usually good..I have a SX-71...thanks for a very good video...

[@charlessmith833]

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.

[@grimace188]

how do you test the mica on the lcr. good video

[@charlessmith833]

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.

[@grimace188]

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

[@charlessmith833]

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.

[@wa4aos]

Hi Charles, I am not aware of a second channel you have.. The one I'm writing from is you name.. What is the name of you other channel?? Yes, your SS conversions would be interesting.. 73, Glenn WA4AOS

[@charlessmith833]

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